From NASA : “Lucy”
8.5.22
What is Lucy?
NASA’s Lucy mission is the first spacecraft launched to explore the Trojan asteroids-a population of primitive asteroids orbiting in tandem with Jupiter.
NASA’s Lucy mission will explore a record-breaking number of asteroids, flying by one asteroid in the solar system’s main asteroid belt, and by seven Trojan asteroids.
About Lucy
Lucy is the first space mission launched to study the Trojan asteroids. Trojans are small bodies that are remnants of our early solar system. They orbit the Sun in two loose groups: one group leading ahead of Jupiter in its orbit, the other trailing behind.
During its 12-year primary mission, Lucy will explore a record-breaking number of asteroids, flying by one main belt asteroid, and seven Trojans.
No other space mission in history has been launched to as many different destinations in independent orbits around our Sun.
This diagram illustrates Lucy’s orbital path. The spacecraft’s path (green) is shown in a frame of reference where Jupiter remains stationary, giving the trajectory its pretzel-like shape. Credit: Southwest Research Institute.
Lucy launched at 5:34 a.m. EDT on Oct. 16, 2021, on a United Launch Alliance Atlas V 401 rocket from Space Launch Complex-41 on Cape Canaveral Space Force Station in Florida. The spacecraft sent its first signal to Earth from its own antenna to NASA’s Deep Space Network at 6:40 a.m. EDT.
“Lucy embodies NASA’s enduring quest to push out into the cosmos for the sake of exploration and science, to better understand the universe and our place within it,” said NASA Administrator Bill Nelson. “I can’t wait to see what mysteries the mission uncovers!”
NASA troubleshoots Lucy after launch
Following the successful launch of NASA’s Lucy spacecraft on October 16, 2021, engineers huddled around a long conference table in Titusville, Florida. Lucy was only starting its 12-year flight, but an unexpected challenge surfaced for the first-ever Trojan asteroids mission.
Data indicated that one of Lucy’s solar arrays powering the spacecraft’s systems — designed to unfurl like a hand fan — hadn’t fully opened and latched. So the team had to figure out what to do next.
Teams from NASA and Lucy mission partners quickly came together to troubleshoot. On the phone were team members at Lockheed Martin’s Mission Support Area outside of Denver. They were in direct contact with the spacecraft.
The conversation was quiet, yet intense. At one end of the room, an engineer sat, folding and unfolding a paper plate in the same manner that Lucy’s huge circular solar arrays operate.
There were so many questions. What happened? Was the array open at all? Was there a way to fix it? Would Lucy be able to safely perform the maneuvers needed to accomplish its science mission without a fully deployed array?
With Lucy already speeding on its way through space, the stakes were high.
NASA troubleshoots Lucy from the ground
Within hours, NASA pulled together Lucy’s anomaly response team, comprising members from science mission lead Southwest Research Institute (SwRI) in Austin, Texas; mission operations lead NASA’s Goddard Space Flight Center in Greenbelt, Maryland; spacecraft builder Lockheed Martin; and Northrop Grumman in San Diego, the solar array system designer and builder.
United in their pursuit to ensure Lucy would reach its fullest potential, the team began an exhaustive deep dive to determine the cause of the issue and develop the best path forward. Given that the spacecraft was otherwise perfectly healthy, the team wasn’t rushing into anything.
A jammed lanyard
Staying focused during many long days and nights, the team worked through options. To evaluate Lucy’s solar array configuration in real time, the team fired thrusters on the spacecraft and gathered data on how those forces made the solar array vibrate. Next, they fed the data into a detailed model of the array’s motor assembly to infer how rigid Lucy’s array was. That helped uncover the source of the issue.
At last, they closed in on the root cause: a lanyard designed to pull Lucy’s massive solar array open was likely snarled on its bobbin-like spool.
After months of further brainstorming and testing, Lucy’s team settled on two potential paths forward.
In one, they would pull harder on the lanyard by running the array’s back-up deployment motor at the same time as its primary motor. The power from two motors should allow the jammed lanyard to wind in further and engage the array’s latching mechanism. While both motors were never originally intended to operate at the same time, the team used models to ensure the concept would work.
The second option: use the array as it was, nearly fully deployed and generating more than 90% of its expected power.
Testing the options
The team mapped out and tested possible outcomes for both options. They analyzed hours of the array’s test footage and constructed a ground-based replica of the array’s motor assembly. Then they tested the replica past its limits to better understand risks of further deployment attempts. They also developed special, high-fidelity software to simulate Lucy in space. Plus, it would gauge any potential ripple effects a redeployment attempt could have on the spacecraft.
After months of simulations and testing, NASA decided to move forward with the first option, using a multi-step attempt to fully redeploy the solar array. On seven occasions in May and June, the team commanded the spacecraft to simultaneously run the primary and backup solar array deployment motors. The effort succeeded, pulling in the lanyard, and further opening and tensioning the array.
The mission continues as planned
The mission now estimates that Lucy’s solar array is between 353 degrees and 357 degrees open (out of 360 total degrees for a fully deployed array). While the array is not fully latched, it is under substantially more tension, making it stable enough for the spacecraft to operate as needed for mission operations.
The spacecraft is now ready and able to complete the next big mission milestone: an Earth-gravity assist in October 2022. Lucy should arrive at its first asteroid target in 2025. During its 12-year journey, the spacecraft will visit seven different asteroids – a main belt asteroid and six Trojans. Lucy will study the geology, surface composition and bulk physical properties of these bodies at close range.
“We started working on the Lucy mission concept early in 2014, so this launch has been long in the making,” said Hal Levison, Lucy principal investigator, based out of the Boulder, Colorado, branch of Southwest Research Institute (SwRI), which is headquartered in San Antonio. “It will still be several years before we get to the first Trojan asteroid, but these objects are worth the wait and all the effort because of their immense scientific value. They are like diamonds in the sky.”
The spacecraft is traveling at roughly 67,000 mph (108,000 kph) on a trajectory that will orbit the Sun and bring it back toward Earth in October 2022 for the spacecraft’s first gravity assist. That maneuver will accelerate and direct Lucy’s trajectory beyond the orbit of Mars. The spacecraft will then swing back toward Earth for another gravity assist in 2024, which will propel Lucy toward the Donaldjohanson asteroid – located within the solar system’s main asteroid belt – in 2025.
Lucy will then journey toward its first Trojan asteroid encounter in the swarm ahead of Jupiter for a 2027 arrival. After completing its first four targeted flybys, the spacecraft will travel back to Earth for a third gravity boost in 2031, which will catapult it to the trailing swarm of Trojans for a 2033 encounter.
“Today we celebrate this incredible milestone and look forward to the new discoveries that Lucy will uncover,” Donya Douglas-Bradshaw, Lucy project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said after the launch.
The Lucy mission is named after the fossilized skeleton of an early hominin (pre-human ancestor) discovered in Ethiopia in 1974 and named “Lucy” by the team of paleoanthropologists who discovered it.
Just as the Lucy fossil provided unique insights into humanity’s evolution, the Lucy mission promises to revolutionize our knowledge of planetary origins and the formation of the solar system, including Earth.
NASA’s Goddard Space Flight Center provides overall mission management, systems engineering, plus safety and mission assurance. Lockheed Martin Space in Littleton, Colorado, built the spacecraft. Lucy is the 13th mission in NASA’s Discovery Program. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Discovery Program for the agency.
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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 [NASA/ESA Hubble, NASA Chandra, NASA Spitzer, and associated programs.] NASA shares data with various national and international organizations such as from [JAXA]Greenhouse Gases Observing Satellite.
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