Tag: Trojan asteroids

Lucy takes first picture of its next target asteroid

9:12 am

Lucy's future route through the solar system
Lucy’s route to the asteroids. Click for original blink animation.

The asteroid probe Lucy, on its way to the orbit of Jupiter to study numerous Trojan asteroids, has taken its first picture of the the main asteroid belt asteroid Donaldjohanson, which it will pass within 600 miles on April 20, 2025.

The map to the right shows the spacecraft’s looping route to get to the Trojans, with that image of Donaldjohanson in the lower right. Though the asteroid is about two miles side, it will remain an unresolved point of light until the day of the fly-by. This image was taken from a distance of 45 million miles. As for the asteroid’s name:

Asteroid Donaldjohanson is named for anthropologist Donald Johanson, who discovered the fossilized skeleton — called “Lucy” — of a human ancestor. NASA’s Lucy mission is named for the fossil.

After this encounter, Lucy will head to the Trojans, where it will visit its first six asteroids (including two binaries) in 2027-2028.

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Lucy about to do close fly-by of Earth in order to slingshot it towards the orbit of Jupiter

9:33 am

Lucy's future route through the solar system
Lucy’s route to the asteroids. Click for original image.

On December 12, 2024 the asteroid probe Lucy will do a very close fly-by of Earth, dipping to only 220 miles of the ground and thus giving it the velocity to fly through asteroid belt between Mars and Jupiter and on to the Trojan asteroids that orbit with Jupiter.

During the gravity assist, the Lucy spacecraft, from Earth’s perspective, will approach from the direction of the Sun. This means that observers on Earth will not be able to see Lucy approaching, as it will be lost in the Sun’s glare. Lucy’s trajectory will bring the spacecraft very close to the Earth, even lower in altitude than the International Space Station. To ensure the safety of the spacecraft as it passes through this region full of Earth-orbiting satellites and debris, NASA has procedures to anticipate and avoid potential collisions. If needed, the spacecraft will execute a small trajectory correction maneuver 12 hours before closest approach to alter the time of closest approach by 1 or 2 seconds — enough to avoid a potential collision.

Shortly after sunset, keen observers in the Hawaiian Islands may be able to catch a glimpse of Lucy as the spacecraft approaches Earth before it passes into Earth’s shadow at 6:14 p.m. HST. Lucy will speed over the continental U.S. in darkness, travelling over 33,000 miles per hour (14.8 kilometers per second), and emerge from Earth’s shadow 20 minutes later at 11:34 p.m. EST. At that time, Lucy may be visible to observers with a telescope in the western regions of Africa and the eastern regions of South America as sunlight reflects off the spacecraft’s large solar panels (observers in the eastern United States will be looking at the much dimmer “back” side of the solar panels, making Lucy harder to see

No imagery is planned for this flyby in order to protect the spacecraft’s science instruments.

After the fly-by, Lucy’s next target will be the main belt asteroid Donaldjohanson in April 2025. Its arrival in Jupiter orbit will follow in 2027.

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Lucy’s first encounter with an asteroid produced surprises

12:39 pm

Dinkinesh, with Salam

At the 55th annual Lunar and Planetary Science Conference presently being held in Texas, the science team for the Lucy asteroid mission presented their first papers outlining what they learned during the spacecraft’s first asteroid encounter, flying past the main belt asteroid Dinkinesh on November 1, 2023.

To the right is the the best image taken at closest approach, at about 270 miles distance, annotated to include the analysis of Dinkinesh’s shape by scientists. As noted in the summary paper [pdf], the asteroid is about a half mile in diameter, and appears to have an equatorial ridge, similar to the ridges found on the near-Earth rubble-pile asteroids Bennu or Ryugu. Dinkinesh is not a rubble pile, however. Though boulder-strewn, it appears more solid, and even has what the scientists call a longitudinal trough, as indicated in the picture.

The ridge overlays the trough implying that it is the younger of the two structures. However, there is as yet no information to better constrain their relative ages, and thus they could potentially have formed in the same event. Indeed, Dinkinesh’s ridge and trough are likely the result of mass failure and the reaccretion of material, and may both be linked to the formation of Selam.

That flyby had produced one major surprise, the existence of a smaller satellite asteroid orbiting Dinkinesh, now dubbed Selam. It is shown in the lower left, as it appeared from behind the main asteroid as Lucy flew past. A later picture however revealed an even greater surprise.
» Read more

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Lucy’s upcoming travels leading to its exploration of the Trojan asteroids

10:16 am

Lucy's future route through the solar system
Click for original image.

The Lucy engineering team today issued an update, outlining the spacecraft’s upcoming fly-bys in 2024 that will carry it to its next asteroid rendezvouses, first with an asteroid in the main belt, and then with four Trojan asteroids orbiting in Jupiter’s orbit but 60 degress ahead.

The map to the right shows this route. The solid red/white line indicates Lucy’s travels in 2024.

In late January, Lucy will begin the series of two deep space maneuvers. On January 31, the spacecraft will briefly operate its main engines for the first time in space. After analyzing the spacecraft’s performance during that brief burn, the team will command the spacecraft to carry out a larger maneuver, nominally on February 3. Combined, these two maneuvers are designed to change the velocity of the spacecraft by around 2,000 mph (approximately 900 meters per second) and will consume roughly half of the spacecraft’s onboard fuel.

That first brief burn will not only test the engines, it will also tell engineers whether one of Lucy’s solar panels — still not fully deployed and latched properly — will not be disturbed by it. If not, they will proceed with the second burn.

After this it will zip past the Earth, which will slingshot it out to Jupiter orbit, passing one main belt asteroid along the way.

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Lucy snaps its first pictures of four of the Trojan asteroids it will visit

10:05 am

Lucy's first look at four Trojan asteroid targets
Click for original movie.

Lucy's route through the solar system
Lucy’s route through the solar system

Though still many millions of miles away and really nothing more than tiny dots moving across the field of stars, the science team for the asteroid probe Lucy have used the probe to take its first pictures of four of the eight Trojan asteroids it will visit during its travels through the solar system, as shown on the map to the right. The dots along its path show where Lucy will fly past asteroids, some of which are binaries.

The image at the top is a screen capture from a very short movie created from all of the images Lucy took of each asteroid. If you click on the picture you will see that movie. As I say, at this distance, more than 330 million miles away, the asteroids are nothing more than dots. The short films of each were obtained by pictures taken over periods from two to 10 hours long, depending on the asteroid.

These asteriods are all in the L4 Trojans, the first that Lucy will visit from ’27 to ’28.

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Lucy science team ends attempt to deploy solar array

9:12 am

Lucy's planned journey
Lucy’s planned mission, the yellow dot indicating approximately
its present position. Click for full image.

The Lucy science team has decided to end further attempts to fully deploy one of the spacecraft’s two solar arrays, leaving it just short of fully deployed.

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 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 press release announcing this decision is horribly written. First, it buries this decision to the release’s last three paragraphs so that it can rave about the brilliance of Lucy’s engineers and scientists in solving the overall problem. Second, it never actually states that this is the decision that has been made. It implies it.

Regardless, it appears the engineers are satisfied that the almost fully deployed array will hold its position for the rest of the mission. They have decided that the risk of trying to fully deploy it is greater than the risk of having it slightly open.

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Lucy solar panel almost completely open

11:19 am

Engineers have now been able to get the one solar panel that did not deploy completely after launch on the Lucy asteroid probe almost completely open.

From May 6 to June 16, NASA’s Lucy mission team carried out a multi-stage effort intended to further deploy the spacecraft’s unlatched solar array. The team commanded the spacecraft to operate the array’s deployment motor for limited periods of time, allowing them to closely monitor the response of the spacecraft. As a result of this effort, the mission succeeded in further deploying the array and now estimates that the solar array is between 353 degrees and 357 degrees open (out of 360 total degrees for a fully deployed array). Additionally, the array is under substantially more tension, giving it significantly more stabilization. The mission team is increasingly confident the solar array will successfully meet the mission’s needs in its current tensioned and stabilized state.

The spacecraft’s orbit is now moving into a position where communications will be limited until October, so further attempts to completely open the array will have to wait until then.

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Astronomers confirm asteroid discovered in 2020 is an Earth Trojan

9:57 am

Astronomers have now confirmed that an asteroid discovered in 2020, dubbed 2020 XL5, is an orbit that makes it the second Earth Trojan asteroid discovered, orbiting the Sun in the same orbit as the Earth but 60 degrees ahead of us.

In December 2020, 2020 XL5 was spotted by astronomers with the Pan-STARRS 1 survey telescope in Hawaii and added to the International Astronomical Union’s Minor Planet Center database. Amateur astronomer Tony Dunn went on to calculate the object’s trajectory using NASA’s publicly-available JPL-Horizon’s software and found that it orbits L4, the fourth Earth-sun Lagrange point, a gravitationally balanced region around our planet and star. 2010 TK7, the first-confirmed Earth Trojan asteroid, is also at L4.

The confirmation that it is definitely a Trojan was then made using both new observations as well as a review of archival images, allowing the astronomers to not only refine the asteroid’s orbit, but determine that it is a C-type asteroid, dark with lots of carbon. The data also suggests that in about 4,000 years, 2020 XL5 will drift from its Trojan point.

There are certainly more such asteroids, but detecting them is difficult from Earth because they can only be seen in twilight.

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Lucy update: Engineers testing solar panel fix on ground

3:44 pm

Engineers for the asteroid probe Lucy have begun doing ground tests on a duplicate solar array motor on Earth to see if their plan will work to get the partly deployed solar panel in space opened and latched.

If all goes right, they are aiming for an April attempt at deploying the panel.

In the meantime, the spacecraft continues its coast outwards, presently being about 30 million miles from Earth. Even though one solar array is not fully open, it appears the spacecraft is getting “ample power” for its present operations. It is unclear if this power — with one solar panel not fully opened — will be sufficient once the spacecraft reaches the region of Jupiter’s Trojan asteroids, much farther from Earth.

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Probe to visit 8 asteroids, not 7

12:11 am

Scientists developing the Lucy mission to visit seven Trojan asteroids that share an orbit with Jupiter have found an eighth satellite they will also be able to visit.

This first-ever mission to the Trojans was already going to break records by visiting seven asteroids during a single mission. Now, using data from the Hubble Space Telescope (HST), the Lucy team discovered that the first Trojan target, Eurybates, has a satellite. This discovery provides an additional object for Lucy to study.

“If I had to bet that one of our destinations had a satellite, it would have been this one,” said SwRI’s Hal Levison, principal investigator of the mission. “Eurybates is considered the largest remnant of a giant collision that occurred billions of years ago. Simulations show that asteroid collisions like the one that made Eurybates and its family often produce small satellites.”

The mission is targeting a 2021 launch date.

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