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  • richardmitnick 5:05 pm on February 20, 2021 Permalink | Reply
    Tags: "DART delayed to November launch as environmental testing begins", Asteroid research, change an asteroid’s orbit by a kinetic impact., , Mission to change an asteroid’s orbit by a kinetic impact., , NASA’s Science Mission Directorate, Planetary defense   

    From NASA Spaceflight and From JHU Applied Physics Lab : “DART delayed to November launch as environmental testing begins” 

    NASA Spaceflight

    From NASA Spaceflight



    Johns Hopkins Applied Physics Lab bloc
    From JHU Applied Physics Lab

    February 19, 2021
    Lee Kanayama

    NASA’s Double Asteroid Redirection Test (DART) spacecraft has been moved to its secondary launch window as it begins thermal and environmental testing. The new launch date of November 24, 2021 is a delay from an original target of July 21.

    DART is NASA’s first planetary defense demonstration, planned to change an asteroid’s orbit by a kinetic impact. DART is a simple technology demonstrator which will attempt to impact Dimorphos, a moonlet of the asteroid Didymos.

    NASA’s Science Mission Directorate (SMD) senior leadership requested a risk assessment to determine the viability of the primary and secondary launch windows. After this assessment was completed, teams determined the primary launch window was no longer viable and the DART team was told to pursue the secondary date.

    “At NASA, mission success and safety are of the utmost importance, and after a careful risk assessment, it became clear DART could not feasibly and safely launch within the primary launch window,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate.

    A part of the decision to move to the secondary date stems from the technical challenges of two main mission critical components: the Didymos Reconnaissance and Asteroid Camera for Optical-navigation (DRACO) imager and the roll-out solar arrays (ROSA). DRACO needs to be reinforced to handle the stress seen during launch and ROSA has had its delivery delayed due to supply chains impacted by the COVID-19 pandemic.

    “To ensure DART is poised for mission success, NASA directed the team pursue the earliest possible launch opportunity during the secondary launch window to allow more time for DRACO testing and delivery of ROSA, and provide a safe working environment through the COVID-19 pandemic.”

    While not the sole factor, the pandemic has made a large impact to the safety of personnel. The delay allows extra flexibility for the remaining spacecraft testing schedule, prioritizing the safety of people alongside mission success.

    NEXT-C ion engine lifted onto the spacecraft at the John Hopkins Applied Physics Laboratory (APL) .

    In the meantime, DART has completed major testing milestones. In November 2020, NASA and Aerojet Rocketdyne personnel installed the NASA Evolutionary Xenon Next-Commercial (NEXT-C) ion engine onto the spacecraft at the John Hopkins Applied Physics Laboratory (APL).

    “The biggest part of that process was lifting the thruster bracket assembly off of the assembly table and positioning it at the top of the spacecraft,” said APL’s Jeremy John, the lead propulsion engineer on DART.

    “This took some care as the thruster’s propellant lines extended below the bottom of the bracket ring and could have been damaged if the lift was not performed properly.”

    Once the engine was lowered onto DART’s central cylinders, fasteners were installed to secure the thruster to the spacecraft. This then allowed APL to connect the electrical harnesses and propellant lines between the thrusters bracket assembly and DART. Afterwards, APL spent several days preparing and testing critical components to ensure a good integration.

    With the NEXT-C engine installed, the spacecraft had both of its propulsion systems onboard. Along with the NEXT-C engine, it will use hydrazine thrusters as its primary propulsion system. The thrusters were installed in May 2020.

    More of DART’s final systems then underwent integration as the spacecraft was prepared for environmental testing. After a pre-environmental review was held in January, the DART team was approved to begin thermal vacuum testing.

    “We’ve worked very hard to get to this critical point in the mission, and we have a great idea of spacecraft performance going into our environmental tests,” said APL’s Elena Adams, DART mission systems engineer.

    “We have an experienced team that is confident with the spacecraft’s ability to withstand the rigors of testing in the next month,” added Ed Reynolds, DART project manager at APL.

    Dart undergoes electromagnetic interference testing via JHUAPL.

    Thermal vacuum testing will be done throughout spring. Once testing is complete, the spacecraft will then be equipped with the ROSA and DRACO. After those are installed, additional vibration and shock testing will take place before it is delivered to Vandenberg Air Force Base in California for launch on a SpaceX Falcon 9.

    DART will launch from Space Launch Complex 4-East (SLC-4E) on a flight-proven Falcon 9, B1063. The booster first supported the Sentinel-6 Michael Freilich mission in November 2020. B1063 may support other missions from Vandenberg prior to launching DART in November 2021.

    SpaceX’s Vandenberg manifest includes a pair of commercial launches: the SARah-1 mission for the German military, and the WorldView Legion Flight 1 launch as early as September.

    Additionally, SpaceX will launch their second dedicated rideshare mission for their smallsat rideshare program, Transporter-2, no earlier than June. The classified NROL-87 mission for the National reconnaissance Office is also scheduled for no earlier than June.

    Falcon 9 B1063 may support any of these missions prior to DART. It is also possible, but unlikely, that B1063 won’t fly any missions between Sentinel-6A and DART.

    No matter the scenario, B1063 will launch DART on a trajectory to the Didymos binary system. After liftoff, the booster will perform a Return to Launch Site (RTLS) landing at Landing Zone 4 (LZ-4), directly adjacent to the launch pad.

    DART is a demonstration mission for future technologies. It is a simple spacecraft that doesn’t include any scientific payloads. Weighing only 500 kilograms, it includes one main instrument, DRACO. DRACO is a camera which will help target the Didymos system while in coast.

    One of the technologies to be tested is the aforementioned NEXT-C ion engine. NEXT-C is based on the NASA Solar Technology Application Readiness (NSTAR) engine which was used on the Dawn and Deep Space 1 spacecrafts.

    NEXT-C was developed by the NASA Glenn Research Center and Aerojet Rocketdyne and designed to have improved performance, thrust, and fuel efficiency compared to other ion engines. NEXT-C is not the primary propulsion system, but its inclusion on DART will help demonstrate its potential for use on future deep-space missions.

    Another technology demonstration is the aforementioned ROSA solar arrays. ROSA is a new type of solar panel that is designed to be more efficient and less bulky than other standard solar panels.

    ROSA was first demonstrated on the International Space Station, after launch on the SpaceX CRS-11 mission in June 2017. It completed all but one of its mission objectives when the solar array failed to lock back in its stowed configuration.

    New, larger types of ROSAs will be launched in 2021 and 2022 on the SpaceX CRS-22, CRS-25, and CRS-26 missions. Called iROSA, six arrays will be launched to help power the ISS for many years to come.

    Infographic of DART’S objectives via NASA/JHUAPL

    DART will also be equipped with thrusters, star trackers, and several sun trackers to help navigate itself to Didymos. Once it reaches the Didymos system, DART will then target and impact Dimorphos at 6.7km/s sometime in the first weeks of October 2022.

    Dimorphos is the moonlet of the asteroid Didymos (Greek for twin). The system was discovered in April 1996 by the Kitt Peak National Observatory, when the asteroid was in close proximity to Earth. Dimorphos was given its name in June 2020.

    Kitt Peak NOIRLab National Observatory of the Quinlan Mountains in the Arizona-Sonoran Desert on the Tohono O’odham Nation, 88 kilometers 55 mi west-southwest of Tucson, Arizona, Altitude 2,096 m (6,877 ft), annotated.

    The system is currently in a 1 AU by 2.2 AU orbit around the Sun. The impact with Dimorphos should cause the speed to change by 0.5 millimeters per second and alter the orbit of Dimorphos around Didymos.

    DART will carry a CubeSat called Light Italian CubeSat for Imaging of Asteroids (LICIA) which will be released five days prior to impact to provide communications and images of the impact.

    DART itself is one of two missions in a joint NASA and European Space Agency (ESA) program called the Asteroid Impact & Deflection Assessment (AIDA). AIDA’s main objective is to understand the effects of an asteroid impact by a spacecraft.

    The ESA will conduct a follow-on mission called Hera, launching on Ariane 6 in 2024.

    Depiction of ESA’s proposed Hera spaceraft.

    Hera will arrive at the binary system in 2027 to observe the changes made by DART’s impact.

    Hera is also a simple spacecraft, weighing about 1,050 kilograms and equiped multiple cameras and a LIDAR Laser Altimeter to determine how effective the impact from DART was in changing Dimorphos’ orbit.

    Hera will also use new autonomous navigation systems while at Dimorphos to will test better and more efficient navigation methods for future interplanetary missions.

    Hera will also carry two CubeSats. The first CubeSat is the Asteroid Prospector Explorer (APEX). APEX will perform surface measurements of two asteroids. Once its main surface data is gathered, APEX will attempt to land for up-close observations of the surface.

    The second CubeSat is called Juventas and will line up with Hera to perform a satellite-to-satellite radio experiment and a low-frequency radar survey of the asteroid interior.

    Once Hera’s mission is complete, Hera will land on one of the two asteroids. The landing will provide insight into the surface material of the asteroid.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Founded on March 10, 1942—just three months after the United States entered World War II—Applied Physics Lab -was created as part of a federal government effort to mobilize scientific resources to address wartime challenges.

    APL was assigned the task of finding a more effective way for ships to defend themselves against enemy air attacks. The Laboratory designed, built, and tested a radar proximity fuze (known as the VT fuze) that significantly increased the effectiveness of anti-aircraft shells in the Pacific—and, later, ground artillery during the invasion of Europe. The product of the Laboratory’s intense development effort was later judged to be, along with the atomic bomb and radar, one of the three most valuable technology developments of the war.

    On the basis of that successful collaboration, the government, The Johns Hopkins University, and APL made a commitment to continue their strategic relationship. The Laboratory rapidly became a major contributor to advances in guided missiles and submarine technologies. Today, more than seven decades later, the Laboratory’s numerous and diverse achievements continue to strengthen our nation.

    APL continues to relentlessly pursue the mission it has followed since its first day: to make critical contributions to critical challenges for our nation.

    Johns Hopkins Unversity campus.

    Johns Hopkins University opened in 1876, with the inauguration of its first president, Daniel Coit Gilman. “What are we aiming at?” Gilman asked in his installation address. “The encouragement of research … and the advancement of individual scholars, who by their excellence will advance the sciences they pursue, and the society where they dwell.”

    The mission laid out by Gilman remains the university’s mission today, summed up in a simple but powerful restatement of Gilman’s own words: “Knowledge for the world.”

    What Gilman created was a research university, dedicated to advancing both students’ knowledge and the state of human knowledge through research and scholarship. Gilman believed that teaching and research are interdependent, that success in one depends on success in the other. A modern university, he believed, must do both well. The realization of Gilman’s philosophy at Johns Hopkins, and at other institutions that later attracted Johns Hopkins-trained scholars, revolutionized higher education in America, leading to the research university system as it exists today.

    NASA Spaceflight , 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 9:39 am on July 20, 2017 Permalink | Reply
    Tags: Asteroid research, , , , ,   

    From NASA- “Asteroids: In Depth” 

    NASA image

    No writer credit

    Artist’s rendering of the the Near Earth Asteroid Rendezvous (NEAR) spacecraft’s rendezvous with the asteroid Eros. NASA.

    Asteroids, sometimes called minor planets, are rocky remnants left over from the early formation of our solar system about 4.6 billion years ago.

    Most of this ancient space rubble can be found orbiting the sun between Mars and Jupiter within the main asteroid belt. Asteroids range in size from Vesta – the largest at about 329 miles (530 kilometers) in diameter – to bodies that are less than 33 feet (10 meters) across. . The total mass of all the asteroids combined is less than that of Earth’s Moon.

    Editor’s note: Even with more than one-half million asteroids known (and there are probably many more), they are still much more widely separated than sometimes seen in Hollywood movies: on average, their separation is in excess of 1-3 million km (depending on how one calculates it).

    Most asteroids are irregularly shaped, though a few are nearly spherical, and they are often pitted or cratered. As they revolve around the sun in elliptical orbits, the asteroids also rotate, sometimes quite erratically, tumbling as they go. More than 150 asteroids are known to have a small companion moon (some have two moons). There are also binary (double) asteroids, in which two rocky bodies of roughly equal size orbit each other, as well as triple asteroid systems.

    The three broad composition classes of asteroids are C-, S-, and M-types. The C-type (chondrite) asteroids are most common, probably consist of clay and silicate rocks, and are dark in appearance. They are among the most ancient objects in the solar system. The S-types (“stony”) are made up of silicate materials and nickel-iron. The M-types are metallic (nickel-iron). The asteroids’ compositional differences are related to how far from the sun they formed. Some experienced high temperatures after they formed and partly melted, with iron sinking to the center and forcing basaltic (volcanic) lava to the surface. Only one such asteroid, Vesta, survives to this day.

    Jupiter’s massive gravity and occasional close encounters with Mars or another object change the asteroids’ orbits, knocking them out of the main belt and hurling them into space in all directions across the orbits of the other planets. Stray asteroids and asteroid fragments slammed into Earth and the other planets in the past, playing a major role in altering the geological history of the planets and in the evolution of life on Earth.

    Scientists continuously monitor Earth-crossing asteroids, whose paths intersect Earth’s orbit, and near-Earth asteroids that approach Earth’s orbital distance to within about 45 million kilometers (28 million miles) and may pose an impact danger. Radar is a valuable tool in detecting and monitoring potential impact hazards. By reflecting transmitted signals off objects, images and other information can be derived from the echoes. Scientists can learn a great deal about an asteroid’s orbit, rotation, size, shape, and metal concentration.

    Several missions have flown by and observed asteroids. The Galileo spacecraft flew by asteroids Gaspra in 1991 and Ida in 1993; the Near-Earth Asteroid Rendezvous (NEAR-Shoemaker) mission studied asteroids Mathilde and Eros;


    The Near Earth Asteroid Rendezvous (NEAR) Shoemaker spacecraft being assembled. NASA.

    and the Rosetta mission encountered Steins in 2008 and Lutetia in 2010.

    ESA/Rosetta spacecraft

    Deep Space 1 and Stardust both had close encounters with asteroids.

    Deep Space 1. NASA.

    NASA Stardust spacecraft

    In 2005, the Japanese spacecraft Hayabusa landed on the near-Earth asteroid Itokawa and attempted to collect samples. On June 3, 2010, Hayabusa successfully returned to Earth a small amount of asteroid dust now being studied by scientists.

    JAXA/Hayabusa 2

    NASA’s Dawn spacecraft, launched in 2007, orbited and explored asteroid Vesta for over a year.

    NASA/Dawn Spacecraft

    Once it left in September 2012, it headed towards dwarf planet Ceres, with a planned arrival of 2015. Vesta and Ceres are two of the largest surviving protoplanet bodies that almost became planets. By studying them with the same complement of instruments on board the same spacecraft, scientists will be able to compare and contrast the different evolutionary path each object took to help understand the early solar system overall.

    Asteroid Classifications

    Main asteroid belt: The majority of known asteroids orbit within the asteroid belt between Mars and Jupiter, generally with not very elongated orbits. The belt is estimated to contain between 1.1 and 1.9 million asteroids larger than 1 kilometer (0.6 mile) in diameter, and millions of smaller ones. Early in the history of the solar system, the gravity of newly formed Jupiter brought an end to the formation of planetary bodies in this region and caused the small bodies to collide with one another, fragmenting them into the asteroids we observe today.

    Trojans: These asteroids share an orbit with a larger planet, but do not collide with it because they gather around two special places in the orbit (called the L4 and L5 Lagrangian points). There, the gravitational pull from the sun and the planet are balanced by a trojan’s tendency to otherwise fly out of the orbit. The Jupiter trojans form the most significant population of trojan asteroids. It is thought that they are as numerous as the asteroids in the asteroid belt. There are Mars and Neptune trojans, and NASA announced the discovery of an Earth trojan in 2011.

    Near-Earth asteroids: These objects have orbits that pass close by that of Earth. Asteroids that actually cross Earth’s orbital path are known as Earth-crossers. As of June 19, 2013, 10,003 near-Earth asteroids are known and the number over 1 kilometer in diameter is thought to be 861, with 1,409 classified as potentially hazardous asteroids – those that could pose a threat to Earth.

    How Asteroids Get Their Names

    The International Astronomical Union’s Committee on Small Body Nomenclature.is a little less strict when it comes to naming asteroids than other IAU naming committees. So out there orbiting the sun we have giant space rocks named for Mr. Spock (a cat named for the character of “Star Trek” fame), rock musician Frank Zappa, regular guys like Phil Davis, and more somber tributes such as the seven asteroids named for the crew of the Space Shuttle Columbia killed in 2003. Asteroids are also named for places and a variety of other things. (The IAU discourages naming asteroids for pets, so Mr. Spock stands alone).

    Asteroids are also given a number, for example (99942) Apophis. The Harvard Smithsonian Center for Astrophysics keeps a fairly current list of asteroid names.

    Significant Dates

    1801: Giuseppe Piazzi discovers the first and largest asteroid, Ceres, orbiting between Mars and Jupiter.
    1898: Gustav Witt discovers Eros, one of the largest near-Earth asteroids.
    1991-1994: The Galileo spacecraft takes the first close-up images of an asteroid (Gaspra) and discovers the first moon (later named Dactyl) orbiting an asteroid (Ida).
    1997-2000 : The NEAR Shoemaker spacecraft flies by Mathilde and orbits and lands on Eros.
    1998: NASA establishes the Near Earth Object Program Office to detect, track and characterize potentially hazardous asteroids and comets that could approach Earth.
    2006: Japan’s Hayabusa becomes the first spacecraft to land on, collect samples and take off from an asteroid.
    2006: Ceres attains a new classification — dwarf planet — but retains its distinction as the largest known asteroid.
    2007: The Dawn spacecraft is launched on its journey to the asteroid belt to study Vesta and Ceres.
    2008: The European spacecraft Rosetta, on its way to study a comet in 2014, flies by and photographs asteroid Steins, a type of asteroid composed of silicates and basalts.
    2010: Japan’s Hayabusa returns its asteroid sample to Earth.
    2010: Rosetta flies by asteroid Lutetia, revealing a primitive survivor from the violent birth of our solar system.
    2011-2012: Dawn studies Vesta. Dawn is the first spacecraft to orbit a main-belt asteroid and continues on to dwarf planet Ceres in 2015.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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 9:50 am on June 25, 2017 Permalink | Reply
    Tags: Asteroid research, , , , ,   

    From GeekWire: “Are asteroids leaving the spotlight? No way, say Asteroid Day activists” 



    June 24, 2017

    Chelsey Ballarte
    Alan Boyle

    An artist’s concept shows asteroids zooming past Earth (NASA / Asteroid Day Illustration).

    NASA may be closing down its grand plan to study a piece of an asteroid up close, but the researchers who focus on near-Earth objects aren’t turning their backs on massive space boulders.

    They say it’s just a matter of time before we’ll be forced to head off a threatening asteroid. On Friday, they’ll be calling attention to the challenge — and what scientists and activists are doing to address it.

    For the past two years, the organizers of Asteroid Day have focused on June 30 as a time to turn an international spotlight on planetary defense. The date marks the anniversary of the Tunguska explosion, a presumed asteroid strike that destroyed half a million acres of forest in Siberia in 1908.

    This year, with the United Nations’ encouragement, 190 countries around the world are planning a total of more than 700 Asteroid Day events, ranging from planetarium shows and virtual reality tours to a 24-hour streaming video marathon.

    Seattle’s Museum of Flight is hosting Asteroid Awareness Day, which will feature fun activities for the kids and live-stream lectures for the grownups.

    Kids in Chile hold up drawings in celebration of Asteroid Day. No image credit.

    One of the organizers of the worldwide Asteroid Day event is former NASA astronaut Ed Lu, executive director of the nonprofit B612 Foundation’s Asteroid Institute.

    More than a decade ago, Lu proposed a method for diverting an asteroid [Nature] that was on a long-term collision course for Earth, by stationing a spacecraft near the asteroid and letting its gravitational attraction pull the asteroid ever so gently into a non-threatening trajectory.

    The “gravity tractor” concept would have been tested during NASA’s Asteroid Redirect Mission, or ARM, which had been planned for the mid-2020s. The Obama administration championed ARM, but now that President Donald Trump is in the White House, it’s being defunded.

    Despite ARM’s cutoff, Lu says other studies focusing on how to deflect potentially threatening asteroids will move forward.

    “We still think a test of a gravity tractor would be very useful,” he told GeekWire.

    Lu points to future space shots such as the European Space Agency’s Asteroid Impact Mission and NASA’s Double Asteroid Redirection Test, or DART, which is designed to smash a probe into an asteroid and see how much its trajectory changes.

    ESA AIM Asteroid Impact Mission

    NASA DART Double Imact Redirection Test vehicle

    NASA’s OSIRIS-REx mission, launched last September, aims to bring bits of an asteroid back to Earth for study in 2023.


    NASA OSIRIS-REx Spacecraft

    NASA says the data produced during ARM’s planning stages will be used to guide preparations for future missions. “Asteroid encounter mission concepts remain of interest due to the broad array of benefits for the human and robotic exploration, science, planetary defense and asteroidal resources communities,” the space agency said in this month’s ARM update.

    Concerns about asteroid threats have risen to fossil evidence suggesting that cosmic impacts were behind ancient mass extinctions — including the demise of the dinosaurs 65 million years ago — as well as more recent events such as 2013’s Chelyabinsk meteor explosion and 1908’s Tunguska blast.

    Scientists estimate that a Tunguska-scale impact might happen every few centuries or so on average. NASA is already tracking more than 15,000 near-Earth asteroids, and Czech astronomers recently reported a new source of potentially hazardous space debris.

    The asteroid-tracking game is likely to become more complex in the 2020s, when the Large Synoptic Survey Telescope, or LSST, goes into full swing in Chile.

    LSST Camera, built at SLAC

    LSST telescope, currently under construction at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    The University of Washington’s DIRAC Institute and the B612 Foundation’s Asteroid Institute are already bracing for what’s expected to be a flood of LSST asteroid discoveries.

    Alan Fitzsimmons, an astrophysicist from Queen’s University Belfast who’s part of Europe’s NEOshield-2 project, says scientists and engineers are making great strides in detecting asteroids – and adds a caveat that’s fitting for Asteroid Day.

    “Astronomers find Near-Earth asteroids every day, and most are harmless,” he said in a news release. “But it is still possible the next Tunguska would take us by surprise, and although we are much better at finding larger asteroids, that does us no good if we are not prepared to do something about them.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

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