NASA's asteroid-touring mission has picked up a ninth target.
In preparation for the Lucy mission to explore a distant class of asteroids called the Trojans, astronomers have been monitoring the targeted space rocks. One day in March, mission personnel gathered 26 different teams from around the world to watch one of those asteroids, 17-mile-wide (27 kilometers) Polymele, appear to pass in front of a star in what scientists call an occultation.
By comparing observations from many different locations on Earth, scientists can precisely measure the shadow an asteroid casts on a star during such an event, allowing them to precisely study the size and shape of the space rock. But during the March observations, which were briefly reported at the time, two of the participating teams saw something different.
"We were thrilled that 14 teams reported observing the star blink out as it passed behind the asteroid, but as we analyzed the data, we saw that two of the observations were not like the others," Marc Buie, a Lucy scientist at the Southwest Research Institute in Colorado, said in a statement.
A diagram of occultation observations show Polymele in the upper left and its newly discovered satellite on the right.
Astronomers reviewing the data concluded that those observations indicated a previously undiscovered space rock orbiting Polymele about 125 miles (200 km) away. "It had to be a satellite," Buie said. The scientists could even determine the newly found asteroid's size: about 3 miles (5 km) across.
The still-unnamed asteroid has since been added to Lucy's ambitious itinerary of space rock flybys. The new detection is the second time that scientists have spotted an extra satellite; in 2020, researchers announced they had spotted a satellite orbiting Eurybates, which Lucy will fly past just a month beforePolymele.
Like most of Lucy's destinations, Polymele, is a Trojan: an asteroid that drifts around the sun in about the same orbit as Jupiter due to the large gas giant's immense gravitational pull. Scientists believe that these "fossil" rocks are the rubble left over from planet formation and could therefore teach us about the early days of our solar system.
About the newly discovered asteroid's name: while some of the discovery team have reportedly nicknamed it "Shaun" after the animated sheep, it won't have an official name until astronomers can confirm the characteristics of its orbit. That likely won't happen any time soon because Polymele's satellite isn't discernible by current Earth-based telescopes. So, unless astronomers get lucky with a future occultation, they may have to wait until Lucy itself swings past the asteroid, scheduled to occur in 2027.
"Lucy’s tagline started out: 12 years, seven asteroids, one spacecraft," NASA's Lucy program scientist, Tom Statler, said in the statement. "We keep having to change the tagline for this mission, but that's a good problem to have."
Quelle: SC
----
Update: 17.10.2022
.
NASA’s Lucy Spacecraft Prepares to Swing by Earth
On Oct. 16, at 7:04 a.m. EDT, NASA’s Lucy spacecraft, the first mission to the Jupiter Trojan asteroids, will skim the Earth’s atmosphere, passing a mere 220 miles (350 kilometers) above the surface. By sling-shotting past Earth on the first anniversary of its launch, Lucy will gain some of the orbital energy it needs to travel to this never-before-visited population of asteroids.
The Trojan asteroids are trapped in orbits around the Sun at the same distance as Jupiter, either far ahead of or behind the giant planet. Lucy is currently one year into a twelve-year voyage. This gravity assist will place Lucy on a new trajectory for a two-year orbit, at which time it will return to Earth for a second gravity assist. This second assist will give Lucy the energy it needs to cross the main asteroid belt, where it will observe asteroid Donaldjohanson, and then travel into the leading Trojan asteroid swarm. There, Lucy will fly past six Trojan asteroids: Eurybates and its satellite Queta, Polymele and its yet unnamed satellite, Leucus, and Orus. Lucy will then return to Earth for a third gravity assist in 2030 to re-target the spacecraft for a rendezvous with the Patroclus-Menoetius binary asteroid pair in the trailing Trojan asteroid swarm.
For this first gravity assist, Lucy will appear to approach Earth from the direction of the Sun. While this means that observers on Earth will not be able to see Lucy in the days before the event, Lucy will be able to take images of the nearly full Earth and Moon. Mission scientists will use these images to calibrate the instruments.
Lucy’s trajectory will bring the spacecraft very close to Earth, lower even than the International Space Station, which means that Lucy will pass through a region full of earth-orbiting satellites and debris. To ensure the safety of the spacecraft, NASA developed procedures to anticipate any potential hazard and, if needed, to execute a small maneuver to avoid a collision.
“The Lucy team has prepared two different maneuvers,” says Coralie Adam, Lucy deputy navigation team chief from KinetX Aerospace in Simi Valley, California. “If the team detects that Lucy is at risk of colliding with a satellite or piece of debris, then--12 hours before the closest approach to Earth --the spacecraft will execute one of these, altering the time of closest approach by either two or four seconds. This is a small correction, but it is enough to avoid a potentially catastrophic collision.”
Lucy will be passing the Earth at such a low altitude that the team had to include the effect of atmospheric drag when designing this flyby. Lucy’s large solar arrays increase this effect.
“In the original plan, Lucy was actually going to pass about 30 miles closer to the Earth,” says Rich Burns, Lucy project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “However, when it became clear that we might have to execute this flyby with one of the solar arrays unlatched, we chose to use a bit of our fuel reserves so that the spacecraft passes the Earth at a slightly higher altitude, reducing the disturbance from the atmospheric drag on the spacecraft’s solar arrays.”
At around 6:55 a.m. EDT, Lucy will first be visible to observers on the ground in Western Australia (6:55 p.m. for those observers). Lucy will quickly pass overhead, clearly visible to the naked eye for a few minutes before disappearing at 7:02 a.m. EDT as the spacecraft passes into the Earth’s shadow. Lucy will continue over the Pacific Ocean in darkness and emerge from the Earth’s shadow at 7:26 a.m. EDT. If the clouds cooperate, sky watchers in the western United States should be able to get a view of Lucy with the aid of binoculars.
“The last time we saw the spacecraft, it was being enclosed in the payload fairing in Florida,” said Hal Levison, Lucy principal investigator at the Southwest Research Institute (SwRI) Boulder, Colorado office. “It is exciting that we will be able to stand here in Colorado and see the spacecraft again. And this time Lucy will be in the sky.”
Lucy will then rapidly recede from the Earth’s vicinity, passing by the Moon and taking a few more calibration images before continuing out into interplanetary space.
“I’m especially excited by the final few images that Lucy will take of the Moon,” said John Spencer, acting deputy project scientist at SwRI. “Counting craters to understand the collisional history of the Trojan asteroids is key to the science that Lucy will carry out, and this will be the first opportunity to calibrate Lucy’s ability to detect craters by comparing it to previous observations of the Moon by other space missions.”
The public is invited to join the #WaveToLucy social media campaign by posting images of themselves waving towards the spacecraft and tagging the @NASASolarSystem account. Additionally, if you are in an area where Lucy will be visible, take a photograph of Lucy and post it to social media with the #SpotTheSpacecraft hashtag. Instructions for observing Lucy from your location are available here.
Hal Levison of Southwest Research Institute (SwRI), in the Boulder Colorado office is the principal investigator. SwRI, headquartered in San Antonio, also leads the science team and the mission’s science observation planning and data processing. NASA Goddard provides overall mission management, systems engineering and the safety and mission assurance for Lucy. Lockheed Martin Space in Littleton, Colorado built the spacecraft, principally designed the orbital trajectory and is providing flight operations. Goddard and KinetX Aerospace are responsible for navigating the Lucy spacecraft. Lucy is the thirteenth mission in NASA’s Discovery Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama.
Quelle: NASA
+++
Mission engineers will track NASA’s Lucy spacecraft nonstop as it prepares to swoop near Earth on Oct. 16 to use this planet’s gravity to set itself on a course toward the Jupiter Trojan asteroids.
But they also will be closely tracking something else: more than 47,000 satellites, debris, and other objects circling our planet. A greater than 1-10,000 chance that Lucy will collide with one of these objects will require mission engineers to slightly adjust the spacecraft’s trajectory.
Although an adjustment is unlikely, and collisions are rare, the chances are increasing as the number of objects in Earth’s orbit grows, NASA experts say.
The International Space Station, for instance, has maneuvered out of the way of space debris 31 times since 1999, including three times since 2020.
“Low-Earth orbit is getting more crowded, so that has to be part of the consideration nowadays, especially for missions that fly low, like Lucy,” said Dr. Dolan Highsmith, chief engineer for the Conjunction Assessment Risk Analysis group at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. The group determines the probabilities of collisions between NASA’s robotic spacecraft and Earth-orbiting objects. NASA’s Johnson Space Center in Houston does the same for crewed spacecraft, such as the space station.
Launched on Oct. 16, 2021, Lucy is on a 12-year-journey to study multiple Trojan asteroids up close. It’ll be the first spacecraft to visit these remnants from the early solar system, helping scientists hone their theories on how the planets formed 4.5 billion years ago and why they ended up in their current configuration.
Read more details about Lucy’s Oct. 16 gravity assist and future trajectory.
But Lucy has a long way to go before it arrives at the Trojans in 2027. The upcoming gravity assist is one of three the spacecraft will rely on to catapult itself to its deep-space targets.
When Lucy comes nearest to Earth for its first gravity assist it will cruise 220 miles (350 km) above the surface. That’s lower than the altitude of the space station and low enough that the spacecraft will be visible with the naked eye from western Australia for a few minutes starting at 6:55 p.m. local time (10:55 UTC). On its way down, Lucy will fly through the most crowded layer of Earth’s orbit, which is monitored by the U.S. Space Force’s 18th Space Control Squadron. The squadron helps NASA identify close approaches.
Engineers began collision analysis for Lucy a week before the spacecraft’s Earth approach. Starting the process any earlier would render collision predictions futile, Highsmith said: “The further you're predicting into the future, the more uncertain you are about where an object is going to be.”
Determining the positions of spacecraft, plus orbiting satellites and debris, is challenging, particularly when trying to anticipate the future. Largely that’s because the Sun plays a major role in pulling or pushing objects around, and future solar activity is hard to predict. For example, the Sun’s activity — how much plasma and radiation it shoots out — affects atmosphere density, and thus how much friction will tug on a spacecraft and slow it down.
So the closer the collision assessment is to the Earth flyby time, the better. NASA sends Lucy’s whereabouts to the Space Force squadron daily. If the squadron determines that Lucy could intersect with something, Highsmith’s group will calculate the probability of a collision and work with the mission team to move the spacecraft, if necessary.
“With such a high value mission, you really need to make sure that you have the capability, in case it's a bad day, to get out of the way,” Highsmith said.
Lucy navigation engineers have two maneuver options ready in case the spacecraft needs to avoid an object. Both maneuvers require engine burns to speed up the spacecraft, which is traveling about 8 miles (12 km) per second. Each maneuver can move Lucy’s closest approach to Earth up by 2 seconds or 4 seconds, respectively.
“That's enough to avoid any one thing that could be in the way,” said Kevin E. Berry, Lucy’s flight dynamics team lead from NASA Goddard.
Quelle: NASA
----
Update: 22.10.2022
.
Lucy completes its first Earth gravity assist after a year in space
A year after its launch, NASA’s Jupiter Trojan asteroid explorer Lucy has completed its first of multiple Earth gravity assists on its journey to explore nine asteroids. Lucy is a first-of-its-kind mission to visit several Trojan asteroids in Jupiter’s L4 and L5 Lagrange points. The mission’s closest approach to Earth occurred on Oct. 16 at 7:04 AM EDT (11:04 UTC).
Lucy Instruments and Flyby
Since its launch on Oct. 16, 2021, Lucy has been operating in cruise mode in a heliocentric orbit around the Sun. The cruise mode allows Lucy substantial autonomy as it coasts between significant events. The three primary science instruments are inactive during cruise mode; however, in November 2021, they were turned on for system checkouts. Mission controllers then turned them back off after the checkouts.
To ensure a close flyby of Earth, Lucy completed multiple correction maneuvers and minor burns to place the spacecraft on a trajectory as close to Earth as possible. In preparation for the flyby, Lucy completed a correction maneuver on June 21.
Since June, Lucy has been in limited communications caused by the thermal conditions of its position relative to Earth and the Sun. Because of this, its high-gain antenna is out of commission, and the craft currently talks to Earth via its low-gain antenna. With the flyby complete, Lucy will soon return to using its high-gain antenna.
A month before the flyby, Lucy was ~14.5 million kilometers from Earth. On Sept. 26, Lucy was 10.4 million kilometers away and activated its Long Range Reconnaissance Imager (L’LORRI) to begin observations of the Didymos/Dimophos binary asteroid system. Lucy started watching the system to capture imagery of NASA’s Double Asteroid Redirection Test (DART) impact of Dimophos—which successfully changed the orbital period of the small asteroid by 32 minutes.
DART featured a camera system named Didymos Reconnaissance and Asteroid Camera for Optical navigation (DRACO). Both DRACO and L’LORRI were initially developed from the LORRI camera onboard New Horizons. Lucy successfully observed DART’s impact and will transmit its imagery in the coming days.
Lucy features three instruments to conduct observations throughout the mission.
L’LORRI is a high-spatial-resolution monochrome visible imager and will provide highly detailed images of the Trojan asteroid surfaces. The John Hopkins University Applied Physics Laboratory provided the imager for Lucy.
Similarly, the spacecraft’s Thermal Emission Spectrometer (L’TES) will detect radiation emitting from the Trojan asteroids. It was developed from OTES (OSIRIS-REx Thermal Emission Spectrometer), which was used on OSIRIS-REx, and the EMIRS (Emirates Mars Infrared Spectrometer), which flew on the Al-Amal Mars mission. Arizona State University built the spectrometer for Lucy.
The third and final instrument is L’Ralph, composed of two sub-instruments: the Multispectral Visible Imaging Camera (MVIC)—a visible-light imager—and the Linear Etalon Imaging Spectral Array (LEISA)—an infrared spectrometer. L’Ralph is based on the Ralph instrument flown onboard New Horizons and will be used to measure silicates, ice, and organics on the surface of the Trojan asteroids. The instrument was built by the Goddard Space Flight Center.
The high-gain antenna and radio telecommunications hardware will measure doppler shifts, helping to determine the mass of the Trojans.
Lockheed Martin built the spacecraft, incorporating the lessons learned from New Horizons and OSIRIS-REx—the latter of which the company also made.
Lucy before it was encapsulated in Atlas V’s 4.2-meter fairing. (Credit: NASA)
This calibration will ensure the spacecraft can get as precise science as possible during its flybys. During its Earth flyby, Lucy attempted to take photos of Ethiopia, where the Lucy fossil—the spacecraft’s namesake—was discovered.
At its closest approach, Lucy came just 351 kilometers from the surface of Earth, which is closer than most orbiting spacecraft—including the ISS. As it was so close to Earth, this made the spacecraft experience slight atmospheric drag that the teams had to compensate for.
“In the original plan, Lucy was actually going to pass about 30 miles (48 km) closer to the Earth,” said Rich Burns, Lucy’s project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “However, when it became clear that we might have to execute this flyby with one of the solar arrays unlatched, we chose to use a bit of our fuel reserves so that the spacecraft passes the Earth at a slightly higher altitude, reducing the disturbance from the atmospheric drag on the spacecraft’s solar arrays.”
Twelve hours before the gravity assist, Lucy could conduct a minor correction burn in case of a risk of collision with orbital debris. As Lucy approached Earth, there was a risk of collision with large amounts of debris and objects in orbit around the planet. This correction maneuver would have altered the close approach by a few seconds. While only a few seconds difference, it would have been enough to avoid a collision. To prepare for the possible burn, NASA scanned Lucy’s path ten days before the gravity assist to check for any potential impacts requiring the burn.
Once retreating from Earth, Lucy gathered a few more calibration images before leaving Earth’s sphere of influence.
As Earth and Jupiter are the closest the two have been in decades, Lucy is as close to Jupiter now as it will ever get. As Jupiter’s orbit is so large, the distance from the planet to its Trojan asteroids is so significant that Lucy—at the Trojans—will be further from Jupiter than during the gravity assist.
The purpose of a gravity assist is to use a planetary body’s gravitational force to alter a spacecraft’s trajectory. When performing a gravity assist, the spacecraft enters a planetary body’s sphere of influence to change its velocity using the planet’s gravity. Lucy used Earth’s gravity to gain speed, boosting the highest point—or aphelion—of its orbit around the Sun.
The gravity assist with Earth changed its aphelion to pass the orbit of Mars. With this, the orbital period for Lucy increased to two years. After completing a single orbit, Lucy will conduct a second Earth gravity assist to provide the energy needed to have its aphelion reach the orbit of Jupiter.
Lucy Update
Since launch, Lucy has operated flawlessly while in heliocentric orbit—despite the issue with one of its two solar arrays.
With a lanyard initially failing to spool and latch the solar array, NASA spooled the lanyard over multiple days to increase the stability and tension of the array—along with its power generation. The solar array is now deployed to around 353-357 of its planned 360 degrees, and the teams are confident in the array’s ability to complete Lucy’s mission in its current state. With the gravity assist complete, NASA and the teams will determine if they will continue with further spooling operations in the future.
The Lucy teams have also continued to observe the Trojan asteroids to understand the targets fully.
In August 2022, the Lucy team announced the discovery of a moon around one of its targets, Polymele. Lucy’s team discovered the moon on March 27. As part of a routine observation, Polymele passed in front of a star, blocking—or occulting—the star’s light. With multiple astronomers situated across the path of the occultation, this allowed the teams to measure the size, location, and shape of Polymele with impressive precision as the star’s light was obstructed or dimmed.
A graphic showing the distance and artist impression of Polymele’s Moon. (Credit: NASA’s Goddard Space Flight Center)
Teams were surprised, however, when multiple observers noticed the star blink twice as the asteroid passed by. The unexpected observations detected an object 200 km away from Polymele. Using the same occultation data, the teams found the moon to be 5 km in diameter, but 27 km long along its widest axis. Teams will not give a name to the moon until its orbit is better determined by either Lucy or a ground-based occultation observation.
This is not the first time the Lucy teams have discovered a moon around one of the asteroid targets. The Lucy teams previously used the Hubble Space Telescope to observe the targets for an unexpected binary pair. An undetected secondary asteroid could confuse the targeting system—or even risk losing the spacecraft. While looking at images from 2018, the teams discovered a moon around Eurybates. With other observations in early 2020, they confirmed the moon’s existence and named it Queta.
Queta is estimated to be less than 1 km in diameter. The discovery of the two moons increased the mission’s target count from seven to nine.
Lucy’s Future—A Flyby Frenzy
Lucy’s second gravity assist with Earth will occur on Dec. 13, 2024. The second gravity assist will begin the spacecraft’s multi-year journey to fly past multiple asteroids. Just five months after the second gravity assist, Lucy will fly by asteroid 52246 Donaldjohanson, located in the main asteroid belt between Jupiter and Mars. The probe will use Donaldjohanson as a rehearsal before reaching the Trojan asteroids.
While only a trial, this flyby will provide the teams with valuable data on C-type asteroids. Measuring only 4 km in diameter, it is one of the smallest objects Lucy will visit. The object is identified to be a fragment of a massive collision from 130 million years ago, which produced the Eriogone family of asteroids.
After flying past Donaldjohanson, Lucy will continue to the L4 Trojan swarm “in front” of Jupiter. Known as the “Greek camp,” the L4 Trojan asteroids congregate around the “leading” Lagrange point, creating a swarm of asteroids.
Lucy’s first flyby of the Trojan asteroids will take place on Aug. 12, 2027, visiting 3548 Eurybates. Eurybates is another C-type asteroid, like Donaldjohanson, but somehow ended up much further from the Sun than its sibling. Eurybates is 64 km in diameter and originated from the same collision as Donaldjohanson. Lucy will visit the asteroid and its moon, Queta, to understand more about how C-type asteroids form, why Eurybates ended up in the Trojan swarm, and more.
A month later, on Sept. 15, Lucy will fly by 15094 Polymele. As a P-type asteroid, this will be the first time a spacecraft flies past a member of the dark, reddish class of asteroid that could be rich in organics. Scientists believe Polymele formed from a collisional fragment of a larger asteroid; Polymele will be compared to other P-type asteroids to determine why it is smaller than others of the same type. Polymele also is accompanied by a moon; Lucy’s flyby will allow closer-up studies of the body to determine its orbit around Polymele.
After a short seven-month coast, Lucy will reach 11351 Leucus, a D-type asteroid. Unlike some other asteroids, Leucus rotates, having a 446-hour day. This rotation gives the surface of Leucus different heating over time compared to other asteroids. Studying Leucus will help scientists understand the composition and formation of D-class asteroids. During observations of the asteroid, its brightness varies from Earth’s perspective, suggesting it has an elongated shape. Leucus is approximately 40 km in diameter.
The final object Lucy will explore in the Greek L4 swarm is the D-type asteroid 21900 Orus. Orus is a larger asteroid, at 51 km in diameter, and can be compared to the smaller Lueucus. While the two are both D-types, Orus has a dark, red surface—much like Eurybates. Lucy will fly by Orus on Nov. 11, 2028.
After completing its flyby of the Greek L4 swarm, Lucy will then begin a return to the inner solar system for its third and final Earth gravity assist. On Dec. 26, 2030, the spacecraft will complete its gravity assist of Earth to aim for the L5 set of Trojan asteroids, also known as the “Trojan camp.”
As the last two targets for Lucy, 617 Patroclus and Menoetius are binary P-type asteroids in the L5 swarm. With diameters of 113 and 104 km, respectively, the two are in a relativity high-inclination heliocentric orbit at 22 degrees. Scientists believe the two may be primordial asteroids originating from the early solar system. Lucy will fly past the pair on March 3, 2033, completing its 12-year primary mission.
During each flyby, the spacecraft will pass 400 to 965 km away from each asteroid, allowing for detailed surface observations. Studying these asteroids will allow scientists to better understand how the solar system was formed.
While the primary mission will be over after its final flyby, Lucy’s exploration will not be finished. In its final orbit, Lucy can continue exploring the trojan asteroids for many more years. NASA will most likely continue its mission until it runs out of fuel—or the agency loses communication with the spacecraft. Once that happens, Lucy will continue on a similar orbit for thousands or even millions of years.
In the future, Lucy’s sister mission, Psyche, will explore the metal asteroid 16 Psyche. Psyche will start its mission once its next launch window opens no earlier than 2023.
Quelle: NS
----
Update: 27.10.2022
.
NASA's Lucy Spacecraft Captures Images of Earth, Moon Ahead of Gravity Assist
NASA’s Lucy spacecraft captured this image (which has been cropped) of the Earth on Oct 15, 2022, as a part of an instrument calibration sequence at a distance of 380,000 miles (620,000 km). The upper left of the image includes a view of Hadar, Ethiopia, home to the 3.2 million-year-old human ancestor fossil for which the spacecraft was named.
Lucy is the first mission to explore the Jupiter Trojan asteroids, an ancient population of asteroid “fossils” that orbit around the Sun at the same distance as Jupiter. To reach these distant asteroids, the Lucy spacecraft’s trajectory includes three Earth gravity assists to boost it on its journey to these enigmatic asteroids.
The image was taken with Lucy’s Terminal Tracking Camera (T2CAM) system, a pair of identical cameras that are responsible for tracking the asteroids during Lucy’s high-speed encounters. The T2CAM system was designed, built and tested by Malin Space Science Systems; Lockheed Martin Integrated the T2CAMs onto the Lucy spacecraft and operates them.
Credits: NASA/Goddard/SwRI
On October 13, 2022, NASA’s Lucy spacecraft captured this image of the Earth and the Moon from a distance of 890,000 miles (1.4 million km). The image was taken as part of an instrument calibration sequence as the spacecraft approached Earth for its first of three Earth gravity assists. These Earth flybys provide Lucy with the speed required to reach the Trojan asteroids — small bodies that orbit the Sun at the same distance as Jupiter. On its 12 year journey, Lucy will fly by a record breaking number of asteroids and survey their diversity, looking for clues to better understand the formation of the solar system.
The image was taken with Lucy’s Terminal Tracking Camera (T2CAM) system, a pair of identical cameras that are responsible for tracking the asteroids during Lucy’s high speed encounters. The T2CAM system was designed, built and tested by Malin Space Science Systems; Lockheed Martin Integrated the T2CAMs onto the Lucy spacecraft and operates them.
Credit: NASA/Goddard/SwRI
Quelle: NASA
----
Update: 29.10.2022
.
The moon is enchanting in new photos from NASA's Lucy asteroid mission
Lucy is using Earth to slingshot the spacecraft to survey Jupiter's Trojan asteroids.
NASA's Lucy mission took stunning closeup images of the moon after using Earth to gain a gravity-assisted boost for its journey to visit Jupiter's Trojan asteroids.
Lucy conducted the first of three planned Earth flybys on Oct. 16, getting as close as 220 miles (360 kilometers) to our planet, making Lucy visible to some viewers on the ground. Hours after its planetary pass, the spacecraft trained its L'LORRI (Lucy Long Range Reconnaissance Imager) camera on our nearest neighbor to capture some impressive photos of the moon in a procedure meant to prepare for the mission's asteroid flybys.
The first image, taken about 6.5 hours after the closest approach to Earth, is a combination of 10 separate 2-millisecond exposures showing the lunar central highlands, with each pixel representing approximately 0.8 miles (1.3 km), according to a statement.
A combination of 10 separate exposures taken by NASA's Lucy spacecraft highlighting the lunar central highlands. (Image credit: NASA/Goddard/SwRI/JHU-APL/Tod R. Lauer (NOIRLab)
A mosaic image, consisting of five separate 1-millisecond exposures, was created using images taken between 7.5 and 8 hours after the flyby of Earth. The tall image shows the moon's rugged, heavily cratered, southern highlands near the bottom of the mosaic, the ancient, lava-filled impact basin Mare Imbrium ("Sea of Rains") near the top, and the terminator, or day-night line, to the left.
Lucy also picked up a single shot of the moon capturing around 600 miles (1000 km) of lunar terrain, mainly showing the vast basin of Mare Imbrium and the Apennine Mountains in the lower-right portion of the image.
The images were taken when Lucy was between 140,000 miles (230,000 km) and 160,000 miles (260,000 km) away from the moon. For comparison, the average distance between Earth and the moon is about 238,900 miles (382,400 km).
As well as delivering impressive pictures, the exercise is helpful for Lucy's main asteroid-surveying mission because it helps scientists understand Lucy's instruments' ability to detect craters, which planetary scientists use to understand the age of surfaces across the solar system.
An shot of the moon taken by NASA's Lucy spacecraft showing the vast basin of Mare Imbrium. (Image credit: NASA/Goddard/SwRI/JHU-APL/Tod R. Lauer (NOIRLab))
Lucy will be the first spacecraft to travel to Jupiter's Trojan asteroids, which orbit the sun in two clumps, one ahead of and one behind the giant planet at gravitational stable "parking spots" called Lagrange points.
Lucy will use a second Earth flyby in 2024 to gain enough speed to visit Trojan asteroids at Lagrange point 4 ahead of Jupiter, before using a final Earth flyby in 2030 to trek to scope out Trojans trailing Jupiter, at Lagrange point 5.
A mosaic image created from images taken by NASA's Lucy spacecraft showing the Mare Imbrium impact basin near the top, the southern highlands near the bottom, and the day-night line to the left. (Image credit: NASA/Goddard/SwRI/JHU-APL/Tod R. Lauer (NOIRLab))
Quelle: SC
----
Update: 2.11.2022
.
NASA's Lucy Spacecraft Eyes the Moon Again
The Multi-spectral Visible Imaging Camera (MVIC), which is a component of the L'Ralph instrument, collected this false-color image of the Moon on Oct. 16, 2022, during the first Earth gravity assist of NASA's Lucy spacecraft. The view of this last quarter Moon is familiar to those on Earth because the spacecraft took this image while it was flying between the Earth and the Moon. Although it looks grey-tone, the image is a composite comprising data from the MVIC violet, green, and near-infrared channels.
The L'Ralph instrument was designed, built, and operated by NASA's Goddard Spaceflight Center.
Credit: NASA/Goddard/SwRI
NASA's Lucy spacecraft captured this image of the Moon on Oct. 16, 2022, from a distance of 150,000 miles (240,000 km). This view of the last quarter Moon is familiar to observers from Earth as the spacecraft took this image while it was in between the Earth and the Moon during its first Earth gravity assist.
The image was taken with Lucy’s Terminal Tracking Camera (T2CAM) system, a pair of identical cameras that are responsible for tracking the asteroids during Lucy’s high-speed encounters. The T2CAM system was designed, built, and tested by Malin Space Science Systems; Lockheed Martin Integrated the T2CAMs onto the Lucy spacecraft and operates them.
Quelle: NASA
----
Update: 27.01.2023
.
NASA’s Lucy Team Announces New Asteroid Target
NASA’s Lucy spacecraft will add another asteroid encounter to its 4-billion-mile journey. On Nov. 1, 2023, Lucy will get a close-up view of a small main-belt asteroid to conduct an engineering test of the spacecraft’s innovative asteroid-tracking navigation system.
The Lucy mission is already breaking records by planning to visit nine asteroids during its 12-year tour of the Jupiter Trojan asteroids, which orbit the Sun at the same distance as Jupiter. Originally, Lucy was not scheduled to get a close-up view of any asteroids until 2025, when it will fly by the main belt asteroid (52246) Donaldjohanson. However, the Lucy team identified a small, as-yet unnamed asteroid in the inner main belt, designated (152830) 1999 VD57, as a potential new and useful target for the Lucy spacecraft.
“There are millions of asteroids in the main asteroid belt,” said Raphael Marschall, Lucy collaborator of the Nice Observatory in France, who identified asteroid 1999 VD57 as an object of special interest for Lucy. “I selected 500,000 asteroids with well-defined orbits to see if Lucy might be traveling close enough to get a good look at any of them, even from a distance. This asteroid really stood out. Lucy’s trajectory as originally designed will take it within 40,000 miles of the asteroid, at least three times closer than the next closest asteroid.”
The Lucy team realized that, by adding a small maneuver, the spacecraft would be able to get an even closer look at this asteroid. So, on Jan. 24, the team officially added it to Lucy’s tour as an engineering test of the spacecraft’s pioneering terminal tracking system. This new system solves a long-standing problem for flyby missions: during a spacecraft’s approach to an asteroid, it is quite difficult to determine exactly how far the spacecraft is from the asteroid, and exactly which way to point the cameras.
“In the past, most flyby missions have accounted for this uncertainty by taking a lot of images of the region where the asteroid might be, meaning low efficiency and lots of images of blank space,” said Hal Levison, Lucy principal investigator from the Southwest Research Institute Boulder, Colorado office. “Lucy will be the first flyby mission to employ this innovative and complex system to automatically track the asteroid during the encounter. This novel system will allow the team to take many more images of the target.”
It turns out that 1999 VD57 provides an excellent opportunity to validate this never-before-flown procedure. The geometry of this encounter—particularly the angle that the spacecraft approaches the asteroid relative to the Sun—is very similar to the mission’s planned Trojan asteroid encounters. This allows the team to carry out a dress rehearsal under similar conditions well in advance of the spacecraft’s main scientific targets.
This asteroid was not identified as a target earlier because it is extremely small. In fact, 1999 VD57, estimated to be a mere 0.4 miles (700 m) in size, will be the smallest main belt asteroid ever visited by a spacecraft. It is much more similar in size to the near-Earth asteroids visited by recent NASA missions OSIRIS-REx and DART than to previously visited main belt asteroids.
The Lucy team will carry out a series of maneuvers starting in early May 2023 to place the spacecraft on a trajectory that will pass approximately 280 miles (450 km) from this small asteroid.
Lucy’s principal investigator is based out of the Boulder, Colorado branch of Southwest Research Institute, headquartered in San Antonio, Texas. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering, and 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 Science Mission Directorate at NASA Headquarters in Washington.
Quelle: NASA
----
Update: 28.01.2023
.
NASA adds asteroid flyby to Lucy mission
NASA's Lucy spacceraft will fly by a small main-belt asteroid in November to test the spacecraft's tracking system as well as its stability given that one solar array is not fully deployed. Credit: NASA/GSFC
WASHINGTON — NASA has added another asteroid flyby to its Lucy mission later this year that will provide a test of its capabilities for future encounters.
NASA announced Jan. 25 that the spacecraft will fly by the small main-belt asteroid 1999 VD57 on Nov. 1. The project selected that asteroid after one scientist collaborating on the mission, Raphael Marschall of France’s Nice Observatory, compared the spacecraft’s trajectory to the orbits of 500,000 asteroids.
Lucy’s current trajectory will take the spacecraft as close at 64,000 kilometers to the asteroid. The spacecraft will perform a series of maneuvers starting in May to adjust its trajectory so that it will instead pass 450 kilometers from the asteroid.
Hal Levison, principal investigator for Lucy at the Southwest Research Institute, said at a Jan. 25 meeting of NASA’s Small Bodies Assessment Group that the mission team has given 1999 VD57 the provisional name of Dinkinesh. That is the Ethiopian name for the Lucy fossil after which the NASA mission is named. The name is pending formal approval by the International Astronomical Union.
Dinkinesh is a S-type asteroid, he said, with a diameter of no more than 800 meters and comparable in size to Bennu, the near Earth asteroid visited by NASA’s OSIRIS-REx mission. It would be the smallest main-belt asteroid that a spacecraft has flown by.
While the flyby will collect images and other data about the asteroid, that is not the primary reason for the close approach. “This is a risk mitigation exercise,” Levison said, focusing on the “terminal tracking system” the spacecraft will use to lock on to the asteroid as it approaches, maximizing the data its instruments collect.
That system has some heritage from past missions but has never been tested in space before. “We decided that it is beneficial to test it out as soon as we can,” he said.
The flyby of Dinkinesh is in addition to another main-belt asteroid, 52246 Donaldjohanson, that it will fly by in 2025. Lucy will then fly by several Trojan asteroids at Jupiter’s distance from the sun between 2027 and 2033.
The Dinkinesh flyby will also test how well it can point at a target given that one of its two large circular solar arrays has not latched into place. “We’re not exactly sure, given that the solar array is not latched, of the pointing stability characteristics of the spacecraft, so this will also help us determine that,” he said.
NASA announced Jan. 19 that it was suspending efforts to fully deploy that solar array after the most recent deployment attempt in December showed only “minimal levels” of progress. The array, the agency said, was nearly fully deployed and appeared to be stable, but did not rule out additional efforts to lock it into place late next year, when the spacecraft makes another Earth flyby.
Levison said that, in the December attempt, there were signs that the array was tensioning, which he said was a positive sign. “It makes us really quite confident that it is safe to fly the mission as-is,” he said.
Quelle: SN
----
Update: 15.04.2023
.
NASA’s Lucy Mission Snaps its First Views of Trojan Asteroid Targets
This story was updated at 4:30 p.m. EST on April 13 to indicate that Lucy will visit two main belt asteroids rather than one.
Some of the asteroids NASA’s Lucy mission will visit are still more than 330 million miles (530 million kilometers) away from the spacecraft, which is more than three times the average distance between Earth and the Sun. But despite the great distance and the comparatively small sizes of these asteroids, Lucy caught views of four of them recently.
From March 25 to 27, 2023, Lucy used its highest resolution imager, L’LORRI, to capture its first views of four Jupiter Trojan asteroids. From left to right in the above image: Eurybates, Polymele, Leucus, and Orus.
Although the four images are all at the same scale, the orientation of each is different, reflecting the different orientations of the L’LORRI camera as it turned to capture each target.
The targets were also observed for different time periods based on their rotation periods:
- Eurybates images were taken over a span of 6.5 hours.
- Polymele, about 2.5 hours.
- Leucus, 2 hours.
- Orus, 10 hours.
These images are the first in a series of planned observations designed to measure how the Trojan asteroids reflect light at higher angles than is observable from Earth. Though the asteroids are still just single points of light in these images, seen against a background of distant stars, the data will help the team choose exposure times for Lucy’s close-up observations of its targets.
Lucy will fly by these asteroids in 2027 and 2028 as the spacecraft travels through a swarm of small asteroids that lead Jupiter in its orbit around the Sun. Lucy is just more than a year into a 12-year voyage that entails close observation of nine of Jupiter’s Trojans — the first space mission ever to visit them — and two main belt asteroids.
Quelle: NASA
----
Update: 13.09.2023
.
NASA’s Lucy Spacecraft Captures its 1st Images of Asteroid Dinkinesh
Credits: NASA/Goddard/SwRI/Johns Hopkins APL
The small dot moving against the background of stars is the first view from NASA’s Lucy spacecraft of the main belt asteroid Dinkinesh, the first of 10 asteroids that the spacecraft will visit on its 12-year voyage of discovery. Lucy captured these two images on Sept. 2 and 5, 2023. On the left, the image blinks between these first two images of Dinkinesh. On the right, the asteroid is circled to aid the eye.
Lucy took these images while it was 14 million miles (23 million km) away from the asteroid, which is only about a half-mile wide (1 km). Over the next two months, Lucy will continue toward Dinkinesh until its closest approach of 265 miles (425 km) on Nov. 1, 2023. The Lucy team will use this encounter as an opportunity to test out spacecraft systems and procedures, focusing on the spacecraft’s terminal tracking system, designed to keep the asteroid within the instruments’ fields of view as the spacecraft flies by at 10,000 mph (4.5 km/s). Lucy will continue to image the asteroid over the next months as part of its optical navigation program, which uses the asteroid’s apparent position against the star background to determine the relative position of Lucy and Dinkinesh to ensure an accurate flyby. Dinkinesh will remain an unresolved point of light during the long approach and won't start to show surface detail until the day of the encounter.
The brightest star in this field of view is HD 34258, a 7.6 magnitude star in the constellation Auriga that is too dim to be seen by the naked eye from Earth. At this distance, Dinkinesh is only 19 magnitude, about 150,000 times fainter than that star. Celestial north is to the right of the frame, which is about 74,500 miles across (120,000 km). The observations were made by Lucy’s high-resolution camera, the L’LORRI instrument – short for Lucy LOng Range Reconnaissance Imager – provided by the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland.
Lucy’s principal investigator, Hal Levison, is based out of the Boulder, Colorado, branch of Southwest Research Institute, headquartered in San Antonio, Texas. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering, and 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 Science Mission Directorate at NASA Headquarters in Washington.
Quelle: NASA