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  • richardmitnick 10:01 am on March 15, 2017 Permalink | Reply
    Tags: A Vision That Could Supercharge NASA, , , , , Hab-Ex, LUVOIR Mission Flyer, , Space Exploration   

    From Many Worlds: “A Vision That Could Supercharge NASA” 

    NASA NExSS bloc

    NASA NExSS

    Many Words icon

    Many Worlds

    2017-03-15
    Marc Kaufman

    1
    LUVOIR Mission Flyer
    An artist rendering of an approximately 16-meter telescope in space. This image was created for an earlier large space telescope feasibility project called ATLAST, but it is similar to what is being discussed inside and outside of NASA as a possible great observatory after the James Webb Space Telescope and the Wide-Field Infrared Survey Telescope. Advocates say such a large space telescope would revolutionize the search for life on exoplanets, as well as providing the greatest observing ever for general astrophysics. (NASA)


    NASA/ESA/CSA Webb Telescope annotated


    NASA/WFIRST telescope

    Let your mind wander for a moment and let it land on the most exciting and meaningful NASA mission that you can imagine. An undertaking, perhaps, that would send astronauts into deep space, that would require enormous technological innovation, and that would have ever-lasting science returns.

    Many will no doubt think of Mars and the dream of sending astronauts there to explore. Others might imagine setting up a colony on that planet, or perhaps in the nearer term establishing a human colony on the moon. And now that we know there’s a rocky exoplanet orbiting Proxima Centauri — the star closest to our sun — it’s tempting to wish for a major robotic or, someday, human mission headed there to search for life.


    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker

    All are dream-worthy space projects for sure. But some visionary scientists (and most especially one well-known former astronaut) have been working for some time on another potential grand endeavor — one that you probably have not heard or thought about, yet might be the most compelling and achievable of them all.

    It would return astronauts to deep space and it would have them doing the kind of very difficult but essential work needed for space exploration in the far future. It would use the very costly and very powerful Space Launch System (SLS) rocket and Orion capsule being built now by NASA and Lockheed Martin respectively. Most important, it would almost certainly revolutionize our understanding of the cosmos near and far.

    At a recent meeting of the House Science Committee, chairman Lamar Smith, said of the hearing’s purpose that, “Presidential transitions offer the opportunities to reinvigorate national goals. They bring fresh perspectives and new ideas that energize our efforts.”

    That said, here’s the seemingly feasible project that fires my imagination the most.

    It has been quietly but with persistence promoted most visibly by John Grunsfeld, the former astronaut who flew to the Hubble Space Telescope three times to fix and upgrade it, who has spent 58 hours on spacewalks outside the Shuttle, and towards the end of his 40 years with the agency ultimately became an associate administrator and head of the agency’s Science Mission Directorate.

    3
    A visualization of the assembly in space of a large segmented telescope, with work being done by astronauts and robots. The honeycomb blocks are parts of the mirror, and the grey cylinders on the right are habitats for astronauts. (NASA)

    His plan: Build a segmented space telescope mirror that is 16 meters (52 feet) in diameter or larger, package it into one or several payload fairings and launch it into deep space. Accompanying astronauts would put it together either at its final destination or at a closer point where it could then be propelled to that destination.

    This would provide invaluable humans-in-space experience, would put the Orion and SLS to very good use in advance of a projected human mission to Mars, and would deploy the most penetrating telescope observing ever. By far.

    No mirror with a diameter greater than 3.5 meters (11.5 feet) has ever been deployed in space, although the the James Webb Space Telescope mirror will be substantially larger at 6.5 meters (21 feet) when launched in 2018. The largest ground telescopes are in the 10-meter (33 foot) range [for now].

    What Grunsfeld’s space behemoth would provide is an unprecedented power and resolution to see back to the earliest point possible in the history of the universe, and doing that in the ultraviolet and visible wavelengths. But perhaps more significantly and revolutionary, it would supercharge the agency’s ability to search for life beyond Earth.

    Like nothing else currently in use or development, it would provide a real chance to answer what is arguably humanity’s most fundamental question: Are we alone in the universe?

    Grunsfeld has been introducing people to the project/vision inside NASA for some time. He also told me that he has spoken with many members of Congress about it, and that most have been quite supportive. Now he’s starting to make the case to the public.

    “We need our leaders to be bold if we want to stay in the forefront of science and engineering,” he said. “Assembling a 16-meter telescope in space would not be easy by any means. But we can do it and — this is the key — it would be transformational. It’s a rational thing to do.”

    His confidence in the possibility of launching the segmented mirror parts and having astronauts assemble them in space comes, he says, from experience. Not only has he flown on the space shuttle five times and has his three very close encounters with the Hubble, but he has also overseen the difficult process of getting the JWST project — with its pioneering segmented, folding mirror — back on track after large budget overruns and delays. He’s also trained in astrophysics and is enamored of exoplanets.

    “If your goal is to search for inhabited planets, you just have to go up to the 16-meter range for the primary telescope mirror,” he said.

    “Think about it: if we sent up something smaller, it will give us important and potentially very intruiging information about what planets might be habitable, that could potentially support life. But then we’d have to send up a bigger mirror later to actually make any detection. Why not just go to the 16-meter now?”

    6
    The strongest driver on the size of the LUVOIR telescope is the desire to have a large sample of exoEarth candidates to study. This figure shows the real stars in the sky for which a planet in the habitable zone can be observed. The color coding shows the probability of observing an exoEarth candidate if it’s present around that star (green is a high probability, red is a low one). This is a visualization of the work of Chris Stark at Space Telescope Science Institute, who created an advanced code to calculate yields of exoplanet observations with different facilities. (C. Stark and J. Tumlinson, STScI)

    While all this may sound to many like science fiction, NASA actually has a team in place studying the science and technology involved with a very large space telescope, and has funded studies of in-space assembly as well.

    The current team is one of four studying different projects for a grand observatory for the 2030s. Their mission is called LUVOIR (the Large UV/Optical/IR Surveyor), and both it and a second mission under study (Hab-Ex) have exoplanets as a primary focus. It was Grunsfeld and Paul Hertz, director of NASA’s astrophysics division, who selected the four concepts for more in-depth study based in large part on astronomy and astrophysics community thinking and aspirations, especially as laid out in the 2013 Thirty-Year Astrophysics Visionary Roadmap.

    7
    Hab-Ex

    The LUVOIR team started out with the intention of studying the engineering and technological requirements — and science returns — of a space telescope between 8 and 16 meters in diameter, while Hab-Ex would look at the 4 to 7 meter option for a telescope designed to find exoplanets. Grunsfeld addressed the LUVOIR study team and encouraged them to be ambitious in their thinking — a message delivered by quite a few others as well. What’s more, a number of study team members were inclined towards the 16-meter version from the onset.

    he LUVOIR team has not addressed the issue of assembly in space — their goals are to understand the science made possible with telescopes of different sizes, to design an observatory that can be repaired and upgraded, and to determine if the technology to pull it all together is within reach for the next decade or two.

    A key issue is how large a folded up mirror the launch vehicle rocket nose cone (the fairing) can hold. While the current version of the SLS would certainly not accommodate a 16-meter segmented mirror, team study scientist Aki Roberge — an astrophysicist at the Goddard Space Flight Center — said that the team just recently got the good news that a next generation SLS fairing looks like it could well hold a folded mirror of up to 15 meters. Quite a few “ifs” involved, but still promising.

    “We’re still in the midst of our work, but it’s clear that a LUVOIR with a large aperture (mirror) gives us a major science return,” she said. “Going up to nine meters would be a major leap forward, and going to 16 would be a dramatic advance on that.”

    “But we have to assess what we gain in terms of going large and what we might lose in terms of added technical difficulty, cost and time.” As is, the 9 or 16-meter project — if selected — would not be ready to launch until the mid 2030s. All the great space observatories and missions have had decades-long gestation periods.

    The results from the LUVOIR and other formal NASA study teams will be reviewed by the agency and then assessed by a sizeable group of experts convened by the National Academy of Sciences for the 2020 Astrophysics Decadal Survey. They set the next decade’s topic and mission priorities for the astronomy and astrophysics communities (as well as others) — assessments that are sent back to NASA and generally followed.

    One of Grunsfeld’s goals, he told me, is to make the assembled-in-space 16-meter telescope a top Decadal Survey priority. While supportive of the LUVOIR efforts, he believes that including astronauts in the equation, deploying a somewhat larger mirror even if the difference in size is not great, and making a mirror that he says will be easier to fix and upgrade than a folded up version, gives the assembled-in-space option the advantage.

    These images, which are theoretical simulations using the iconic Hubble Deep Field image, are adjusted to reflect the light collected by telescopes of different sizes. They show the increased resolution and quality of images taken by a 16-meter telescope, a 9-meter, and the Hubble Space Telescope, which is 2.4 meters in diameter. They illustrate pretty clearly why astronomers and exoplanet hunters want ever larger telescope mirrors to collect those photons from galaxies, stars and planets.

    Whether or not the LUVOIR project is selected to be a future NASA flagship observatory, and whether or not it will be an assembled-in-space version of it, many at the agency clearly see human activity and habitation in space (as well as on planets or moons) as a necessary and inevitable next step.

    Harley Thronson is the senior scientist for Advanced Concepts in Astrophysics at Goddard, and he has worked on several projects related to how and where astronauts might live and work in space. He said this research goes back decades, having gained the attention of then-NASA Administrator Dan Goldin around 2000. It has recently experienced another spurt of interest as the agency has been assessing opportunities for human operations beyond the immediate vicinity of the Earth.

    “It’s inevitable that the astronomy community will want and need larger space observatories, and so we have to work out how to design and build them, how and where they might be assembled in space, and how they can be serviced,” Thronson said. The JWST will not be reachable for upgrades and servicing, and Congress responded to that drawback by telling NASA will make sure future major observatories can be serviced if at all possible.

    Thronson said that he supports and is inspired by the idea of a 16-meter space telescope, and he agrees with Grunsfeld that assembly in space is the wave of the future. But he said “I’m not quite as optimistic as John that we’re ready to attack that now, though it would be terrific if we were.”

    Part of Thronson’s work involves understanding operation sites where space telescopes would be most stable, and that generally involves the libration points, where countervailing gravity pulls are almost neutralized. LUVOIR, like JWST, is proposed for the so-called Sun-Earth L-2 point, about one million miles outward from Earth where the Earth and sun create a gravitational equilibrium of sorts.

    Thronson said there has been some discussion about the possibility of assembling a telescope at a closer Earth-moon libration point and then propelling it towards its destination. That assembly point could, over time, become a kind of depot for servicing space telescopes and as well as other tasks.

    8
    One of the locations in relatively nearby space where a space telescope would have a stable gravitational environment. (NASA


    LaGrange Points map. NASA

    As a sign of the level of interest in these kind of space-based activities, NASA last year awarded $65 million to six companies involved in creating space habitats for astronauts on long-duration missions in deep space.

    At the time, the director of NASA’s Advanced Exploration Systems, Jason Crusan, said that “the next human exploration capabilities needed beyond the Space Launch System rocket and Orion capsule are deep space, long duration habitation and in-space propulsion. We are now adding focus and specifics on the deep space habitats where humans will live and work independently for months or years at a time, without cargo supply deliveries from Earth.”

    Not surprisingly, building and maintaining telescopes and habitats in space will be costly (though less so than any serious effort to send humans to Mars). As a result, how much support NASA gets from the White House, Congress and the public — as well as the astronomy and astrophysics communities — will determine whether and when this kind of space architecture becomes a reality.

    John Grunsfeld, who has walked the walk like nobody else, plans to be stepping up his own effort to explain how and why this is a vision worth embracing.

    See the full article here .

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    About Many Worlds

    There are many worlds out there waiting to fire your imagination.

    Marc Kaufman is an experienced journalist, having spent three decades at The Washington Post and The Philadelphia Inquirer, and is the author of two books on searching for life and planetary habitability. While the “Many Worlds” column is supported by the Lunar Planetary Institute/USRA and informed by NASA’s NExSS initiative, any opinions expressed are the author’s alone.

    This site is for everyone interested in the burgeoning field of exoplanet detection and research, from the general public to scientists in the field. It will present columns, news stories and in-depth features, as well as the work of guest writers.

    About NExSS

    The Nexus for Exoplanet System Science (NExSS) is a NASA research coordination network dedicated to the study of planetary habitability. The goals of NExSS are to investigate the diversity of exoplanets and to learn how their history, geology, and climate interact to create the conditions for life. NExSS investigators also strive to put planets into an architectural context — as solar systems built over the eons through dynamical processes and sculpted by stars. Based on our understanding of our own solar system and habitable planet Earth, researchers in the network aim to identify where habitable niches are most likely to occur, which planets are most likely to be habitable. Leveraging current NASA investments in research and missions, NExSS will accelerate the discovery and characterization of other potentially life-bearing worlds in the galaxy, using a systems science approach.
    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

     
  • richardmitnick 9:07 am on August 31, 2015 Permalink | Reply
    Tags: , , NASA CYGNUS, , Space Exploration   

    From NASA SpaceFlight: “Enhanced Cygnus to help Orbital ATK meet CRS contract by 2017” 

    NASA Spaceflight

    NASA Spaceflight

    August 31, 2015
    Chris Gebhardt

    NASA CYGNUS
    CYGNUS

    The first flight of Orbital ATK’s Enhanced Cygnus resupply craft for the International Space Station is set to launch in December atop an Atlas V rocket. Helping Orbital ATK return to flight operations, the Enhanced Cygnus spacecraft will allow the company to meet their initial CRS cargo up-mass contract with NASA in just four more missions.

    December’s upcoming OA-4 mission of Cygnus to the International Space Station (ISS) will be the first flight of Cygnus under the newly merged company Orbital ATK and the first flight of the company’s resupply vehicle on a non-Antares rocket.

    The OA-4 mission will be lofted to orbit on a United Launch Alliance Atlas V rocket launching from the Cape Canaveral Air Force Station, FL.

    2
    United Launch Alliance Atlas V rocket

    Cygnus’ ingrained adaptability to launch on rockets other than Antares has allowed Orbital ATK to purchase an Atlas V rocket for the OA-4 mission and, in turn, gain significant up-mass capability on the OA-4 mission than would have been possible launching on Antares.

    This additional up-mass capability supported by the powerful Atlas V rocket’s core stage and its Centaur upper stage will allow Orbital ATK to reach a major milestone in the company’s Commercial Resupply Contract (CRS) with NASA sooner than expected.

    In an exclusive interview with NASASpaceflight.com, Frank DeMauro, CRS Program Director for Orbital ATK stated that “with the upgraded Antares 230 and then with the couple of Atlas V [missions], we’re actually going to meet our initial cargo delivery requirement through the OA7 mission.”

    While Enhanced Cygnus on an Atlas V is part of what will allow Orbital ATK to meet their cargo delivery up-mass requirement on the OA-7 mission instead of the OA-8 mission, the enhanced version of Cygnus was planned from the inception of the program and is not a change stemming from the Orb-3 launch failure in October 2014.

    According to Mr. DeMauro, “we had planned from the beginning of the program that there would actually be two versions of Cygnus.”

    The first variant, the Standard Cygnus, flew on all three previous Orbital CRS ISS missions (including October’s failed Orb-3 CRS mission) in 2014 as well as the predecessor COTS Demo flight of Cygnus to ISS in Sept. 2013.

    The Standard Cygnus, flying on Orbital’s Antares 110, 120, and 130 series rockets, could carry a maximum payload of approximately 2,000 kg (4,400 lbs) to ISS.

    Enhanced Cygnus, on Atlas V, will be capable of lifting a maximum payload of 3,500 kg (7,700 lbs) to the ISS and 3,200 kg (7,100 lbs) of payload to ISS on the Antares 230 series rocket — set to debut early next year as part of Orbital ATK’s return to flight path.

    According to Mr. DeMauro, “we had planned a long time ago that we would start flying, on the fourth mission, a longer cargo module — with essentially more volume to carry more cargo.”

    NASA Enhanced CYGNUS
    NASA Enhanced CYGNUS

    In fact, Enhanced Cygnus will have a stretched Pressurized Cargo Module (PCM) that will increase the total interior PCM volume to 27 cubic meters — an increase from the 18 cubic meter PCM volume of the Standard Cygnus.

    Moreover, the stretched PCM is not the only aspect of the Enhanced Cygnus that will debut on December’s OA-4 flight. Orbital ATK ultraflex solar arrays will also grace the Enhanced Cygnus later this year.

    “One of the more visible changes was the change-out from the flat panel solar array to an Orbital ATK ultraflex solar array — which deploys sort of like a fan,” stated Mr. DeMauro.

    “The biggest difference between [the Orbital ATK ultraflex array] and a more traditional array is the structure behind the cells. It’s essentially a lightweight material to which the cells are mounted, as opposed to a more heavy structure.

    “The key is to develop the array in such a way that you have a small stowed package with a highly reliable deployment system, but that when it’s open, the amount of surface area you get is about the same as you would get from a regular flat panel area.”

    This approach to the Enhanced Cygnus design will allow Orbital ATK to have a lower mass solar array that produces the same amount of power as the previous generation Cygnus solar arrays.

    Importantly, though, the visual changes of the Enhanced Cygnus aren’t the only improvements Orbital ATK has made to its ISS resupply craft.

    Lessons learned in terms of loading cargo into Cygnus have led to a significant increase in the amount of cargo that can be arranged within Cygnus.

    According to Mr. DeMauro, “As we learned other things we could do in the cargo module, we’ve actually significantly increased the amount of cargo we can load in the same volume on the Enhanced Cygnus.

    “So that’s why you’re seeing, for a relatively low percentage of size increase of the PCM, a significant increase in cargo carrying capability.”

    With its introduction on the OA-4 mission in December, Enhanced Cygnus will become the only variant of Cygnus used for ISS resupply missions through the completion of Orbital ATK’s CRS contract with NASA — a contract that was recently extended by three missions.

    Following the OA-7 mission in 2016, the OA-8E, OA-9E, and OA-10E missions will launch between 2017 and the first part of 2018.

    Those added missions will continue to focus solely on Cygnus’ pressurized up-mass capability to ISS.

    When asked about possible Cygnus variants to allow for external cargo deliveries to ISS, Mr. DeMauro stated that Orbital ATK’s “focus right now and moving forward is on pressurized up-mass and pressurized disposal.

    “What we do, what NASA is counting on us to do, is to deliver as much pressurized up-mass as possible. And then also, very importantly, the removal of disposal cargo from inside the Station.”

    Mr. DeMauro specifically noted that this service from Cygnus compliments the other contracted services NASA has for Station resupply efforts, and that there are no plans to redesign Cygnus for external supply delivery ops at Station.

    If the current schedule holds, the first Enhanced Cygnus will launch to the ISS atop an Atlas V rocket – flying in the 401 configuration (with a 4-meter fairing, zero solid rocket boosters, and a single-engine Centaur upper stage) – on 3 December 2015 during a launch window that opens at 17:55 EST and closes at 18:25 EST (22:55 – 23:25 GMT).

    See the full article here.

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    NASASpaceFlight.com, now in its eighth year of operations, is already the leading online news resource for everyone interested in space flight specific news, supplying our readership with the latest news, around the clock, with editors covering all the leading space faring nations.

    Breaking more exclusive space flight related news stories than any other site in its field, NASASpaceFlight.com is dedicated to expanding the public’s awareness and respect for the space flight industry, which in turn is reflected in the many thousands of space industry visitors to the site, ranging from NASA to Lockheed Martin, Boeing, United Space Alliance and commercial space flight arena.

    With a monthly readership of 500,000 visitors and growing, the site’s expansion has already seen articles being referenced and linked by major news networks such as MSNBC, CBS, The New York Times, Popular Science, but to name a few.

     
  • richardmitnick 11:57 am on August 20, 2015 Permalink | Reply
    Tags: , , , Space Exploration,   

    From The Conversation: Talking to Mars: new antenna design could aid interplanetary communication 

    Conversation
    The Conversation

    August 20, 2015

    Authors
    Jean Paul Santos
    PhD Student in Electrical Engineering at University of California, Los Angeles

    Joshua M Kovitz
    PhD student in Electrical Engineering at University of California, Los Angeles

    Yahya Rahmat-Samii
    Professor of Electrical Engineering/Electromagnetics at University of California, Los Angeles

    1
    Jean Paul Santos with the finished 4×4 sub-array antenna assembly that may help rovers talk directly with Earth. Matthew Chin, CC BY-NC-ND

    When people think about antennas, they often picture old television sets with “rabbit ears” – two metal rods poking above the screen. Essentially, antennas are devices that allow the wireless transfer or reception of radio signals. They come in various sizes and shapes. For instance, it’s your cellphone’s antenna that allows you to stream videos, post a social media status, use GPS to find a restaurant and call a friend.

    2
    Mars rovers need to transmit all their cool findings back to Earth somehow. NASA/JPL-Caltech, CC BY

    This wireless technology opened the door to space exploration. Neil Armstrong’s voyage to the moon was possible because antennas allow communication between engineered space vehicles and Earth. It’s an antenna that allows the Mars rovers to communicate with Earth from millions of miles away. To gather valuable scientific data, rovers often take measurements, pictures and video, then send them back home via radio waves at high frequencies, through their antennas.

    Currently, the Mars rovers primarily rely on what’s called indirect or relay communications. They send their data to a much larger satellite antenna, called the Mars Reconnaissance Orbiter, which then sends it all on to Earth at high transmission rates. The frequencies of transmission are in X-band, near 8 GHz, which has a radio wavelength close to 1.5 inches.

    3
    It would be nice to cut out the middleman in transmitting communication back and forth between Earth and Mars. Joshua Kovitz, Jean Paul Santos and Yahya Rahmat-Samii, CC BY-NC-ND

    Our group here at the UCLA Antenna Research, Analysis, and Measurement Laboratory specializes in designing advanced antenna systems, including spacecraft antennas for future space missions. Now, with help from engineers at NASA’s Jet Propulsion Laboratory (JPL), we’re working to create a small yet powerful antenna that could allow the Mars rover to communicate directly with Earth, potentially cutting out the middleman.

    At the present time, the Mars rover can relay information to the Mars Reconnaissance Orbiter for just 15 minutes twice a day due to orbit conditions. Allowing the Mars rover to connect directly with Earth could offer a big increase in communication time – much more data could be sent back and forth when the rover is in direct line-of-sight. A direct link would also be an advantage in the event that large satellite orbiters are no longer available.

    The challenge is to create an upgraded link that can do the job but also fit on the next upcoming Mars rover mission, Mars2020.

    NASA Mars 2020 rover
    Mars 2020 schematic


    Download here.

    Good signal strength over astronomical distances

    5
    Like a bigger bucket in the rain, a larger antenna will receive a stronger radio signal. Joshua Kovitz, Jean Paul Santos and Yahya Rahmat-Samii, CC BY-NC-ND

    We need to achieve good signal strength in the small space set aside on the rover for an antenna. The physics of radio waves tells us that the larger the antenna, the more power it can receive. Think of an antenna as like a bucket collecting rain. The larger the bucket’s opening, the more water it can catch at any given time. As long as the antenna is much bigger than the wavelength, it works the same way: the bigger it is, the more power it can receive or transmit. With more power, the data can be better extracted from the radio waves that carry pictures, video and commands. Extracting the data works similarly to modern television signals, with audio and video carried by radio waves.

    For future Mars rovers, 40 cm x 40 cm x 5 cm is potentially the maximum volume that the antenna can occupy. With the available area set, our job as antenna engineers is to figure out the best and most efficient way to use all the space given to maximize the amount of power.

    Other criteria for the antenna to work on a Mars 2020 rover include:

    must be lightweight
    must run on the prospective power available for radio transmissions – about 100 Watts, the same amount used by a bright incandescent lightbulb
    must be aligned with the Earth’s antenna. A robotic supporting arm called a gimbal can mechanically position the antenna. The Curiosity mission used a similar gimbal to steer its high-gain antenna.

    Adding up antenna elements into one array

    The big idea is to combine many small antennas (often called antenna elements) to make an altogether larger antenna. You can think of this antenna concept as like an organ system. An individual organ, such as the heart, can operate in and of itself. It’s when it’s combined with other organs that it can maintain a human being.

    6
    The key is to get a really good antenna element that can join forces in an array. Note the half-E shape of the single element. Joshua Kovitz, Jean Paul Santos and Yahya Rahmat-Samii, CC BY-NC-ND

    Our antenna “organs” begin with a specialized geometry that looks like half of the letter “E.” We derived it from the original E-shaped antenna design we’ve already had a lot of success with. This novel “half-E” shape allows the antenna to transmit and receive radio signals which are circularly polarized. Basically that means the polarization of the radio waves can be oriented in a special configuration that helps reduce the effects of atmospheric gases and particles on the waves as they travel. It can also help to make sure a strong signal is maintained even if the rover itself or the antennas are moving.

    When enough of these antenna elements – 256 in this case – are combined together just right into what antenna engineers call an array, the whole can transmit and receive much greater power.

    7
    The antenna assembly is compact enough to fit within the rover’s space limitations. Joshua Kovitz, Jean Paul Santos and Yahya Rahmat-Samii, CC BY-NC-ND

    The overall complete array should fit nicely within the required volume, whose maximum area is comparable to a standard 12-inch by 12-inch chessboard. It’s a compact way to pack the same antenna power into a much smaller space than if we relied on larger, bulkier dish antennas that have the added disadvantage of being harder to stow on the rover during flight.

    8
    Santos and Kovitz soldering the antenna assembly. Jean Paul Santos, CC BY-NC-ND

    Transforming a novel idea into a real prototype

    Of course, any exciting venture in engineering research worth its salt comes with an experimental demonstration. As a first step, we designed, built and tested one of the smaller 4-by-4 element sub-arrays. We used simulation software to first understand how the antenna would perform in real-life scenarios. We drew the antenna in a computer-aided drafting program, which included all the necessary materials such as metals, ceramics and wires.

    9
    Santos testing the antenna prototype’s characteristics in an anechoic (no echo) chamber. Joshua Kovitz, CC BY-NC-ND

    After much fine-tuning and verifying that the antenna meets the JPL requirements mentioned above, we began physically constructing it. And it took us several attempts. We started by taking a couple of pieces of lightweight ceramic coated with metal and used photolithography and chemical etching to create the specialized antenna geometry. Since this antenna is several layers, we had to solder them all together. When we tested the antenna’s actual performance, we were gratified to see our prototype behaved the way our simulations predicted!

    With a successful prototyping of the 4-by-4 element sub-array, the next step would be to prototype the full-scale 16-by-16 element antenna. Ultimately, we’d like to test it on the Mars rover system itself at a NASA test site here on Earth. We hope that with this design, JPL can potentially augment its communication system so the rover can successfully call home directly.

    See the full article here.

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    The Conversation US launched as a pilot project in October 2014. It is an independent source of news and views from the academic and research community, delivered direct to the public.
    Our team of professional editors work with university and research institute experts to unlock their knowledge for use by the wider public.
    Access to independent, high quality, authenticated, explanatory journalism underpins a functioning democracy. Our aim is to promote better understanding of current affairs and complex issues. And hopefully allow for a better quality of public discourse and conversation.

     
  • richardmitnick 2:19 pm on August 14, 2015 Permalink | Reply
    Tags: , Space Exploration   

    From NASA: “NASA Awards Grants for Technologies That Could Transform Space Exploration” 

    NASA

    NASA

    Aug. 14, 2015
    Joshua Buck
    Headquarters, Washington
    202-358-1130
    jbuck@nasa.gov

    1
    These petri dishes contain designer microbes lit by LED lights. These microbes are based on tiny organisms called cyanobacterium, and can possibly be used to convert toxic atmospheres of planets like Mars and Venus into more hospitable environments. Synthetic biology involves the design and construction of biological devices and systems for useful purposes to develop transformative biological tools and technologies. Credits: NASA

    NASA has selected eight university-led proposals to study innovative, early stage technologies that will address high-priority needs of America’s space program.

    The selected proposals for unique, disruptive or transformational space technologies will investigate challenges in the areas of solar cell operations at high temperatures, atmospheric entry model development, synthetic biology applications for space exploration and dynamic tensegrity-based space structures. Tensegrity is a property of structures that employs continuous tension and discontinuous compression to produce exceptionally strong structures for their mass.

    “These early career researchers will provide fuel for NASA’s innovation engine,” said Steve Jurczyk, associate administrator for NASA’s Space Technology Mission Directorate at the agency’s Headquarters in Washington. “Technology drives exploration, and investments in these technologies and technologists is essential to ensure NASA and the nation have the capabilities necessary to meet the challenges we will face as we journey to Mars. The faculty selected and their colleagues help assure a robust university research community dedicated to advanced space technology development.”

    The awards are approximately $200,000 per year, up to a possible three years of research, for outstanding early-career faculty who research space technologies that are high priorities for NASA missions.

    The selected NASA Early Career Faculty proposals are:

    Robust Planning for Dynamic Tensegrity Structures — Kostas Bekris of Rutgers University in New Brunswick, New Jersey
    Synthetic Biology for Recycling Human Waste into Food, Nutraceuticals, and Materials: Closing the Loop for Long-Term Space Travel — Mark Blenner of Clemson University in Clemson, South Carolina
    Lightweight and Flexible Metal Halide Perovskite Thin Films for High Temperature Solar Cells — Joshua Choi of the University of Virginia in Charlottesville
    Dynamics and Control of Tensegrity Space Manipulators — James Forbes of the University of Michigan, Ann Arbor
    Advanced Physical Models and Numerical Algorithms to Enable High-Fidelity Aerothermodynamic Simulations of Planetary Entry Vehicles on Emerging Distributed Heterogeneous Computing Architectures — Matthias Ihme of Stanford University in Stanford, California
    Reduced Order Modeling for Non-equilibrium Radiation Hydrodynamics of Base Flow and Wakes: Enabling Manned Missions to Mars — Marco Panesi of the University of Illinois, Urbana-Champaign
    Engineering Cyanobacteria for the Production of Lightweight Materials — Fuzhong Zhang of Washington University in St. Louis
    High Temperature InGaN-based Solar Cells — Yuji Zhao, Arizona State University, Tempe.

    These proposals have the potential to yield significant rewards for space exploration by:

    allowing solar cells to function at reasonable levels of efficiency in high-temperature environments;
    improving the process of identifying the most effective thermal protection systems for entering various atmospheres;
    providing the means to produce food, medical supplies and building materials on site at distant destinations using synthetic, biology-based approaches; and
    enabling more capable and affordable space missions through the development of tensegrity technologies that permit large, reconfigurable structures such as antennas, solar arrays and observatories, as well as lightweight landers.

    NASA’s Early Career Faculty efforts are an element of the agency’s Space Technology Research Grants Program. This program is designed to accelerate the development of technologies originating from academia that support the future science and exploration needs of NASA, other government agencies and the commercial space sector.

    For more information about NASA’s Space Technology Research Grants Program, visit:

    http://go.nasa.gov/1Wg3hbA

    For more information about the Space Technology Mission Directorate, visit:

    http://www.nasa.gov/spacetech

    See the full article here.

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    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

     
  • richardmitnick 1:21 pm on July 21, 2015 Permalink | Reply
    Tags: , , NASA SLS, Space Exploration   

    From NASA Goddard: “Lunar IceCube Wins Coveted Slot on Exploration Mission-1” 

    NASA Goddard Banner
    Goddard Space Flight Center

    July 21, 2015
    Lori Keesey
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    Lunar Icecube
    Morehead State University and Goddard are partnering to create the Lunar IceCube mission shown in this artist’s rendition.
    Credits: Morehead State University

    Age of Deep-Space Exploration with CubeSats Heralded

    Lunar IceCube has won a coveted slot as one of 12 diminutive secondary payloads to deploy during the first planned flight in 2018 of NASA’s next-generation Space Launch System (SLS) and the second for its Orion Multi-Purpose Crew Vehicle — an event that scientists say will signal a paradigm shift in interplanetary science.

    Morehead State University in Kentucky is leading the six-unit (6-U) CubeSat mission, with significant involvement from scientists and engineers at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the Massachusetts-based Busek Company. It will be among the “first batch” of small, fully operational satellites to deploy and gather scientific information in deep space, said Pam Clark, the mission’s science principal investigator at Goddard. Although CubeSats are evolving rapidly, scientists so far have confined their use to investigations in low-Earth orbit.

    Under the university-led partnership, Morehead State’s Space Science Center will build the 6-U satellite bus and provide communications and tracking support via its 21-meter ground station antenna. Busek will provide the state-of-the-art electric propulsion system and Goddard will construct IceCube’s only miniaturized instrument, the Broadband InfraRed Compact High Resolution Explorer Spectrometer (BIRCHES). The instrument will prospect for water in ice, liquid, and vapor forms from a highly inclined elliptical lunar orbit. Goddard also will model a low-thrust trajectory taking the pint-size satellite to lunar orbit with very little propellant.

    2
    Morehead State University professor Ben Malphrus, who is leading the Lunar IceCube mission, stands in front of the university’s 21-meter ground station antenna that will be handling the mission’s communications needs. Credits: Randy Evans/Dataseam

    “Goddard scientists and engineers have deep experience in areas that are critical to interplanetary exploration,” said mission Morehead State University Principal Investigator Benjamin Malphrus, explaining why the university teamed with Goddard. “The significant expertise at Goddard, combined with Morehead State’s experience in smallsats and Busek’s in innovative electric-propulsion systems, create a strong team.”

    See the full article here.

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    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

    NASA Goddard Campus
    NASA/Goddard Campus
    NASA

     
  • richardmitnick 1:52 pm on April 13, 2015 Permalink | Reply
    Tags: , , , Space Exploration   

    From Caltech: “Explaining Saturn’s Great White Spots” 

    Caltech Logo
    Caltech

    04/13/2015
    Kathy Svitil

    1
    This image, taken by NASA’s Cassini spacecraft in February 2011, shows a huge storm in Saturn’s northern hemisphere.
    Credit: NASA/JPL-Caltech/Space Science Institute

    Every 20 to 30 years, Saturn’s atmosphere roils with giant, planet-encircling thunderstorms that produce intense lightning and enormous cloud disturbances. The head of one of these storms—popularly called “great white spots,” in analogy to the Great Red Spot of Jupiter—can be as large as Earth. Unlike Jupiter’s spot, which is calm at the center and has no lightning, the Saturn spots are active in the center and have long tails that eventually wrap around the planet.

    Six such storms have been observed on Saturn over the past 140 years, alternating between the equator and midlatitudes, with the most recent emerging in December 2010 and encircling the planet within six months. The storms usually occur when Saturn’s northern hemisphere is most tilted toward the sun. Just what triggers them and why they occur so infrequently, however, has been unclear.

    Now, a new study by two Caltech planetary scientists suggests a possible cause for these storms. The study was published April 13 in the advance online issue of the journal Nature Geoscience.

    Using numerical modeling, Professor of Planetary Science Andrew Ingersoll and his graduate student Cheng Li simulated the formation of the storms and found that they may be caused by the weight of the water molecules in the planet’s atmosphere. Because these water molecules are heavy compared to the hydrogen and helium that comprise most of the gas-giant planet’s atmosphere, they make the upper atmosphere lighter when they rain out, and that suppresses convection.

    Over time, this leads to a cooling of the upper atmosphere. But that cooling eventually overrides the suppressed convection, and warm moist air rapidly rises and triggers a thunderstorm. “The upper atmosphere is so cold and so massive that it takes 20 to 30 years for this cooling to trigger another storm,” says Ingersoll.

    Ingersoll and Li found that this mechanism matches observations of the great white spot of 2010 taken by NASA’s Cassini spacecraft, which has been observing Saturn and its moons since 2004.

    NASA Cassini Spacecraft
    Cassini

    The researchers also propose that the absence of planet-encircling storms on Jupiter could be explained if Jupiter’s atmosphere contains less water vapor than Saturn’s atmosphere. That is because saturated gas (gas that contains the maximum amount of moisture that it can hold at a particular temperature) in a hydrogen-helium atmosphere goes through a density minimum as it cools. That is, it first becomes less dense as the water precipitates out, and then it becomes more dense as cooling proceeds further. “Going through that minimum is key to suppressing the convection, but there has to be enough water vapor to start with,” says Li.

    Ingersoll and Li note that observations by the Galileo spacecraft and the Hubble Space Telescope indicate that Saturn does indeed have enough water to go through this density minimum, whereas Jupiter does not. In November 2016, NASA’s Juno spacecraft, now en route to Jupiter, will start measuring the water abundance on that planet. “That should help us understand not only the meteorology but also the planet’s formation, since water is expected to be the third most abundant molecule after hydrogen and helium in a giant planet atmosphere,” Ingersoll says.

    NASA Galileo
    Galileo

    NASA Hubble Telescope
    NASA/ESA Hubble

    NASA Juno
    Juno

    The work in the paper, Moist convection in hydrogen atmospheres and the frequency of Saturn’s giant storms, was supported by the National Science Foundation and the Cassini Project of NASA.

    See the full article here.

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    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”
    Caltech buildings

     
  • richardmitnick 3:01 pm on February 4, 2015 Permalink | Reply
    Tags: , Space Exploration,   

    From U Tartu: “Researchers of Tartu develop ‘space grease’” 

    U Tartu bloc

    University of Tartu

    30.01.2015

    The Estonian Materials Technologies Competence Centre (MATECC) has just signed an agreement with the European Space Agency. Researchers of the centre and of the University of Tartu will start to develop a nanotechnology lubricant suitable for extreme conditions.

    Shuttles and equipment used in space consist of numerous elements and have several friction-prone details, the surface of which must be greased to ensure smooth operation. Due to extreme temperature, pressure and radiation conditions, conventional oils and greases cannot be used in space. This is why solid substances such as molybdenum disulfide and graphite are preferred for space usage. These materials are continuously developed to achieve a sufficiently long action time and reliability required for space applications.

    Now that Estonia is about to become a full member of the European Space Agency, Estonian enterprises also get the chance to contribute to space-related development. Researchers involved in the activities of the Estonian Materials Technologies Competence Centre have been studying friction mechanisms and the characteristics of materials on the nanoscale for several years already and developed novel additives to lubricant oils together with the industry. The acquired knowledge and experience will be also used in the new cooperation project with the European Space Agency.

    Martin Järvekülg, Research Fellow in Materials Science at the University of Tartu and Project Manager of the Estonian Materials Technologies Competence Centre said that the aim of the cooperation between the centre and the European Space Agency is to develop a lubricant based on the combination of nanoparticles and ionic liquids. In normal environment, ionic liquids are liquid salts with extremely low volatility.

    “The novel lubricant must be effective under both normal pressure and under vacuum, both in high and low temperatures,” said Järvekülg. If the researchers succeed in combining the strengths of liquid and solid lubricants in the new compound material, the results of the project can be also used elsewhere, where the extreme environment or the specifics of application place higher demands on the materials.

    The first stage of the project lasts for one year and will, among others, also involve the researchers and degree students of the Institute of Chemistry and the Institute of Physics of the University of Tartu. One of the main implementers of the project is Triinu Taaber, Specialist of the Estonian Materials Technologies Competence Centre and doctoral student of the UT.

    1
    Triinu Taaber Photo: Andres Tennus/UT

    According to the Vice Rector for Development of the University of Tartu Erik Puura, the signed international agreement proves that the competence and facilities of the researchers of Tartu are world-class in the field of nanotechnology.

    See the full article here.

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    U Tartu Campus

    UT is Estonia’s leading centre of research and training. It preserves the culture of the Estonian people and spearheads the country’s reputation in research and provision of higher education. UT belongs to the top 3% of world’s best universities.

    As Estonia’s national university, UT stresses the importance of international co-operation and partnerships with reputable research universities all over the world. The robust research potential of the university is evidenced by the fact that it is the only Baltic university that has been invited to join the Coimbra Group, a prestigious club of renowned research universities.

    UT includes nine faculties and four colleges. To support and develop the professional competence of its students and academic staff, the university has entered into bilateral co-operation agreements with 64 partner institutions in 23 countries.

     
  • richardmitnick 5:02 pm on February 2, 2015 Permalink | Reply
    Tags: , , Space Exploration,   

    From Space.com: “Does Humanity’s Destiny Lie in Interstellar Space Travel? (Op-Ed)” 

    space-dot-com logo

    SPACE.com

    January 27, 2015
    Donald Goldsmith

    temp
    An artist’s interpretation of utilizing a wormhole to travel through space, Thorne kick-started a serious discussion among scientists about whether or wormhole travel is possible. Credit: NASA

    Imagine a time when humans, having spent decades exploring the solar system through landings on Venus and Mars; passages by the largest asteroids; close-up surveys of Jupiter and its giant moons; repeated loops through Saturn’s system of rings and satellites; detailed photography of Uranus, Neptune and Pluto; and even landing on a comet, finally create a coherent plan to travel through interstellar space to reach the nearest stars and their planets.

    That time has almost arrived. Once NASA’s Dawn spacecraft arrives at the asteroid Ceres in March of this year , and the space agency’s New Horizons spacecraft flies by Pluto in July, humans will have completed the solar system exploration described above. They will have done so, of course, by creating complex and highly capable spacecraft that not only secure high-resolution images of the objects they encounter, but also roll across planetary surfaces to measure local conditions in a dozen different ways, including spectroscopic and chemical analysis of the composition and history of each object.

    NASA Dawn Spacescraft
    NASA/Dawn

    NASA New Horizons spacecraft
    NASA/New Horizons

    Will humans ever replace robotic explorers?

    To many of us, the success of our automated spacecraft heralds the long-awaited moments when humans finally land on Mars, Ganymede (Jupiter’s largest moon) or Titan (Saturn’s largest moon), eventually to establish self-sustaining colonies that might provide a continuing opportunity to maintain our existence if our home planet were to become uninhabitable. The interplay between our logical wishes to deepen our knowledge of the solar system and our gut-level desires for personal encounters with new situations — always present though not always acknowledged — has governed humans’ ever-shifting plans to explore our nearby cosmic environment for half a century.

    Just about everyone welcomes new information about the solar system, but what many really — really — want is for humanity to plant its boots on new soil, as Earth-bound explorers have done for many centuries. Lonely humans in space speak directly to our emotions, but pioneering spacecraft far less so. (Even an apparent exception, such as the hero of the movie “WALL-E,” connects with us through its seeming humanity, a fact that won’t surprise anyone who reflects for a moment on how storytelling works.)

    Some facts remain evident: Human exploration of space is dangerous and expensive, requiring the provision of food and water, recycling of wastes, significant amounts of energy to run those systems, protection against harsh radiation and a return journey (or not, depending on volunteers’ propensities). In comparison, automated spacecraft have only modest energy requirements, and can last for decades or more. As time passes, this comparison progressively favors machines, since they (thanks to humans!) become ever more competent, while our bodies evolve at a much slower pace.

    As the brilliant physicist Freeman Dyson explains in the new podcast available at RawScience.tv, “Instruments have gotten enormously … humans are really out of it. If you want to go to space, that’s for fun, not for science … This is not understood by the people in charge [of planning for future exploration missions].”

    To be sure, when we dream of the far future, we can easily envision (thanks, in part, to many science-fiction stories and films) beings that combine today’s human bodies with advanced technology to produce a human-machine hybrid far more capable of long journeys and survival in strange situations than individuals are today.

    Humanity’s destiny in space

    Dyson’s argument in favor of machines counts for little among those who insist — who know — that our destiny lies in the presence of humans, not our mechanistic surrogates, in space. For many of us, this knowledge runs more deeply than argument can reach. A glance at the history of the United States’ space program reminds us of the many times, during the 40-plus years since the last lunar landing, that NASA has attempted to produce a reasonable plan to send humans beyond low-Earth orbit — only to have the expense of such projects, combined with the lack of a clear focus for astronaut activity, lead to their abandonment. Because the manned lunar program basically served as a counterpunch to Soviet efforts in space, once NASA and the United States achieved their initial goal of landing on the moon, they proved unable of following a coherent plan for future space exploration by humans.

    What do these ambitions tell us about the future of interstellar exploration? Even before we consider human versus automated journeys, we should note that any answers to this question begin with a number: 1 million. The stars nearest to the sun lie at distances approximately 1 million times the distance to Mars at its closest approach to Earth. This ratio implies that travel to the stars at speeds our best spacecraft are capable of will take hundreds of thousands of years, and this, in turn, implies that any interstellar exploration will require either a civilization that knows how to plan for the long haul, or the ability to make spacecraft that can travel much faster — perhaps 10,000 times more rapidly — than what we have now. (I’ll save the discussion of “wormholes” like those seen in the movies “Contact” and “Interstellar ” for later.)

    On the fast track, or slow and steady?

    Consider spacecraft that could carry astronauts through space at speeds approaching the speed of light, conferring two great advantages on the crew. Most obviously, the journey requires less time — only a few years to reach the nearest stars, and only a couple of decades to span the distances to the closest thousand stars. In addition, time slows down at near-light velocities — by a factor of 10, for example, for those who travel at 99.5 percent the speed of light. At that velocity, an astronaut who makes an interstellar journey covering 50 light years in each direction would age by only 10 years, but would return to an Earth where everyone has aged by 100 years. (Those who suspect that Einstein’s theory of relativity creates a “twin paradox” — that the traveler and those who stay behind should each see time slow down by a factor of 10 — can find an excellent explanation of the apparent paradox in David Mermin’s book “Space and Time in Special Relativity” (Waveland, 1989).)

    But how can we hope to move through space at close to the speed of light? More than 50 years ago, Dyson — who, even then, created intriguing and controversial ideas at the Institute for Advanced Study in Princeton, New Jersey — proposed that nuclear explosions could accelerate a spacecraft to ever-higher speeds. The “Project Orion” study, directed by Ted Taylor, though largely Dyson’s brainchild, envisioned that a series of nuclear explosions would strike a “pusher plate” attached to the rear of a spacecraft, eventually accelerating the spacecraft to any desired velocity.

    The concept remains theoretically feasible, though one can easily see that the expense would be enormous. As Dyson recalls in the RawScience podcast, by using the power of nuclear explosions, the Orion spacecraft could provide “both fast acceleration and fast travel, which nothing else could do … In principle, the idea was good,” Dyson said, but “it had one fatal flaw: The bombs are highly radioactive … As soon as you had the test-ban treaty … Orion was dead.”

    Even if we manage to accelerate a spacecraft to velocities close to the speed of light (10,000 times faster than our fastest space probes), any spacecraft moving at near-light velocities encounters a significant problem. The same special-relativity rules that allow a traveler to return to Earth much younger than her twin brother who stayed home also imply that collisions with space debris — even tiny dust particles — inevitably pose great dangers. [Photos: Step-by-Step Guide to NASA’s EFT-1 Orion Spacecraft Test Flight ]

    When the spacecraft encounters dust and pebbles, the objects’ near-light velocities, relative to the craft, enormously elevate their effective masses. An impactor’s increase in mass, together with the tremendous collision speeds, call for enormous amounts of shielding to protect anyone inside the spacecraft. Hence, any plans to travel through the Milky Way at near-light speeds must embrace not only a truly massive propulsion system, but also enough shielding to protect the humans inside the craft.

    Thinking in centuries

    Nevertheless, Dyson’s Orion concept remains, in many ways, the gold standard for visions of interstellar travel. In the recent podcast, Dyson noted that the name “Orion” has been passed on to NASA’s most recent spacecraft design not for an interstellar vehicle, but for a far more modest craft to take astronauts to other worlds in the solar system. Dyson also identified the most basic requirement for interstellar spaceflight: a society capable of long-term planning and execution. “If you want to have a program for moving out into the universe, you have to think in centuries, not in decades.”

    That necessity for a long-term vision poses a serious barrier to interstellar journeys in a society that has great difficulty planning for even the next five years.

    If we are prepared to think in centuries, as Dyson recommends, we should ask the key technological question: What prospects exist for interstellar space travel at comparatively low velocities? In the decades since this question first seriously arose, theorists have provided plenty of answers, which build on the success of our current interplanetary space probes. If you want to probe deeply into them, the coordinated websites of the Tau Zero Foundation and Centauri Dreams offer useful information on this topic. And if you want to examine a representative plan for interstellar travel, I recommend the PowerPoint presentation created by Steve Kilston, an astronomer who spent much of his career at Ball Aerospace (and with whom I have been friends since our undergraduate days). Kilston’s “Plausible Path to the Stars” envisions the creation — in approximately 500 years — of a cylindrical spaceship that will carry a million inhabitants, will rotate in order to simulate Earth’s gravity, will travel at 0.2 percent of the speed of light, and could reach the few dozen nearest stars in 10,000 years’ time.

    In other words, Kilston’s “Plausible Path,” like any other low-velocity journey, requires that generations upon generations of spacefarers pass their entire lives short of their goal. Today, this plan would attract few volunteers. But if human society came to feel sure of its long-term viability, so that our time horizon stretched beyond the current limits of (at most) our grandchildren’s lifetimes, the situation would become quite different. Perhaps the wisest aspect of Kilston’s plan lies in its final prelaunch phase: a 100-year cruise through the solar system to demonstrate the full feasibility of the spacecraft and the willingness of its crew to pass their lives in space.

    Thus, a practical, technologically reasonable plan to explore our cosmic environment rests simply upon achieving a society in which a 100-year journey, and a few thousand years of travel time, seem both logical and desirable. To see how far we now stand from this goal, we may merely compare a film based on Kilston’s “Plausible Path” with a movie like “Avatar” or “Interstellar.” In today’s world, almost no one is interested in moving from a situation in which months of spacecraft travel is far too long to one that tolerates multi-thousand-year journeys. Instead, we must hope for a better tomorrow.

    The wormhole option

    If we don’t want to wait, what about taking the “Interstellar” route and using a wormhole to pass near-instantaneously from here to there? Kip Thorne, a physicist at the California Institute of Technology who’s an expert on the subject — and whose screenplay inspired “Interstellar” — has written a book to accompany the film: “The Science of Interstellar” (W.W. Norton and Company, 2014). In the book, Thorne demonstrates that humans cannot rule out wormhole travel, but there is no guarantee that this method actually works, or that it could allow safe conduct through the voids of space.

    Physicists have recently suggested that the Milky Way could contain — or even be! — a giant wormhole. On the other hand, an argument against wormhole travel, or at least against its easy operation, lies in the fact that no creatures of a more advanced civilization appear to be popping out of wormholes in our solar system. A similar argument can be made against time travel, at least in the backward direction, since we have yet to encounter beings from the future who have decided to visit our present.

    To be frank, concepts of interstellar travel have progressed only modestly since Dyson envisioned the Orion project decades ago. Yes, layers of refinement have been added: “Slow” versus “fast” spaceflight has been debated and scored, experience has now given some indications of how well humans can survive long periods in space, and theoretical physics has provided some tantalizing possibilities that might make such journeys much easier than they now appear. But the big picture has not changed: First, we must figure out how to live successfully for the long term on Earth, and then we can go to the stars.

    See the full article here.

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  • richardmitnick 5:37 pm on December 7, 2014 Permalink | Reply
    Tags: , , , Space Exploration,   

    From SPACE.com: “China Has Big Plans to Explore the Moon and Mars” 

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    SPACE.com

    December 03, 2014
    Leonard David

    China continues to ramp up its space activities, which include a new launch complex, more powerful boosters and the construction of a large space station, as well as plans for complex robotic missions to the moon and Mars.

    For example, China’s “little fly” spacecraft looped around the moon and returned to Earth Nov. 1 (Beijing time) after eight days of flight, parachuting safely down in northern China’s Inner Mongolia.

    The capsule used seven kinds of thermal protection materials, returning data that will be applied to China’s Chang’e 5 robotic lunar sample return mission, which is slated to launch in 2017 from the new Wenchang Satellite Launch Center.

    In the human spaceflight arena, China’s manned space agency is readying the Wenchang Satellite Launch Center for liftoff around 2016, which will be followed by the crewed Shenzhou 11 spacecraft and a Tianzhou cargo vessel that will rendezvous with the lab.

    Chinese officials expect that the core space station module will be launched around 2018, and the orbiting facility is slated to be completed by about 2022.

    All of these plans form a comphrehensive space exploration agenda for the coming years.

    c
    China’s new Wenchang Satellite Launch Center on Hainan island is reportedly completed and will handle an array of Earth-orbiting and deep-space missions. Credit: CMSE

    Incremental steps

    The Lunar Exploration Analysis Group (LEAG), an assembly of experts convened by NASA to assist in planning the scientific exploration of the moon, is eyeing China’s growing lunar exploration capacity.

    “China has had a well developed, focused plan, and they are using incremental steps to lunar exploration,” said Jeffrey Plescia, chairman of LEAG. “Each mission has achieved the primary goal — orbiters, landing, rovers — leading up to sample return and then on to humans.”

    The objective of the recent test of the lunar sample return capsule was to demonstrate gear that can return from the moon and land safely.

    “I would guess that, given the pieces they have tested, that they have a high probability of success on the sample return,” Plescia told Space.com. “My personal guess, though, is that their lunar exploration, while trying to do some science, is more focused on the geopolitical theater. They are demonstrating that they have the technical capability of doing the most sophisticated deep-space activities. They have a program, and they can keep to the schedule and accomplish mission goals on time.”

    d
    China made history on Dec. 14, 2013 with the successful landing of its Chang’e 3 lander carrying the Yutu rover. The mission is the first soft-landing on the moon since 1976 and made China only the third country ever perform the lunar feat.
    Above: China’s lunar rover Yutu (“Jade Rabbit”) is seen by a camera on the country’s Chang’e 3 lander after both successfully landed on the moon together on Dec. 14, 2013

    In comparison, Plescia said, “the United States has been floundering around for decades, trying to figure out what to do.”

    In the meantime, the U.S. has de-emphasized manned missions into space, instead focusing on a robotic science program that is “myopic at best,” as it’s narrowly focused on Mars, Plesica said. However, he added that the U.S.’ Mars missions have provided a lot of surface detail and made a number of impressive discoveries.

    “The real problem [in the U.S.] is the lack of direction and commitment,” Plescia said. “I think, like others, that the moon is key to understanding how to live and work in space and explore the solar system.”

    Expanded access to space

    China’s space program has been extremely active recently, said Dean Cheng, a research fellow on Chinese political and security affairs at the Heritage Foundation in Washington, D.C.

    Several Shijian and Yaogan satellites — two series of spacecraft that are believed to have military functions — have been launched in 2014. The “little fly” probe circumnavigated the moon, performing a vital precursor of any human lunar missions, he said. Also, the Chinese recently displayed a Mars rover at a popular air show, and there are reports that the country could dispatch a robotic Red Planet mission by the end of the decade.

    In the interim, Chinese officials have discussed the possibility of even more powerful rockets than the still-under-development Long March 5 booster, Cheng said. In addition, the new Wenchang launch site on Hainan is apparently ready for a public unveiling, he said.

    “This new facility will be China’s southernmost launch site, with obvious benefits in terms of payload. It will also be China’s first launch facility that is located on the coast,” Cheng said. “Larger Chinese launch vehicles will now be possible, since they can be shipped to the new launch facility by sea, rather than [be] limited by Chinese railway tunnel widths and track curvature.”

    “When the Wenchang satellite launch center is officially opened, it will mark a further step in China’s efforts to expand its access to space,” with the ability to hurl heavier payloads into space, Cheng told Space.com. “These are expected to include a Chinese space station, lunar sample retrieval mission and a Mars rover.”

    f
    China’s Automated Re-Entry Capsule
    A recent ceremony in China showcased the automated re-entry capsule that flew a circumlunar trajectory and returned to Earth under parachute. The capsule housed various items, including the Chinese flag. Credit: CASC

    Long-term commitment

    China also established new space ties with 4M (the Manfred Memorial Moon Mission), the first private mission to the moon, suggesting an interesting link between China and private space entrepreneurs, Cheng said. There are also reports of cooperation between China and Russia, and one or more joint space ventures may be announced in 2015, he said.

    “All of this is a reminder that China’s space development efforts are likely to continue sustained interest under the new Chinese leader, Xi Jinping, as it did under his predecessors Hu Jintao, Jiang Zemin and Deng Xiaoping,” Cheng said.

    “Despite reports of a slowing economy, at this point, there does not seem to be much evidence that the space development effort is suffering any budgetary cutbacks,” he added.

    Indeed, China’s long-term commitment to space development is one of that nation’s great strengths, Cheng said, “as it supports sustained development of program[s], rather than a ‘feast or famine’ approach.”

    3
    China is readying the Tiangong 2 space lab for liftoff around 2016. Once in orbit, it would be followed by the piloted Shenzhou 11 spacecraft and a Tianzhou cargo vessel that will rendezvous with the lab. Credit: CCTV

    Investment in space

    “China is continuing to pursue a number of goals it decided upon decades ago,” said Gregory Kulacki, senior analyst and China project manager for the Global Security Program at the Union of Concerned Scientists (UCS), based in Cambridge, Mass.

    Like Cheng, Kulacki believes the launch facility on the island of Hainan is a key new capability.

    “It has been on the drawing board for quite a long time, and has experienced numerous delays, but is now prepared to serve as the home space port for China’s new generation of wider-bodied launch vehicles that can carry larger payloads,” Kulacki told Space.com. “These new vehicles have also experienced some delays, but China has no fixed deadlines to meet.”

    “As these major new pieces of China’s space infrastructure come online, including new satellite manufacturing facilities in Tianjin, the pace and scale of its activities in space will continue to grow,” Kulacki said. “China already has considerable space assets on orbit, and its investment in space will continue to increase significantly over the next several decades.”

    People who claim China is pursuing an asymmetric space warfare strategy misread the nation’s intentions, Kulacki said. Rather, “the strategic objective of Chinese space policy is not to exploit asymmetry between China and the United States, but to end it,” he said.

    See the full article here.

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