Lucy engineers again attempt to complete deployment of solar array

Lucy solar panel graphic
Artist’s impression of solar panel

On November 7, 2022, the Lucy science team made another attempt to complete the deployment of one of the spacecraft’s two solar arrays, as shown in the graphic to the right. After launch that array failed to deploy properly, and though later attempts have gotten it mostly open, it has not latched tight.

On Monday, Nov. 7, the spacecraft was instructed to point toward the Sun and operate the array deployment motors for a short period of time. As expected, the latest attempt deployed the wing incrementally forward, but it did not latch. The operation did succeed in providing the team with data to evaluate the array’s status and ascertain any changes since the last deployment attempt on June 16.

During this analysis, the team identified that a small vibration occurred as the unlatched array interacted with the spacecraft’s attitude controller while the array was pointed toward Earth and at a cold temperature. The vibration did not occur as a result of the deployment activity itself. While this vibration is too small to pose a risk to the spacecraft in its current state, further array deployment attempts have been paused while the attitude controller is updated to resolve this issue. In the meantime, the spacecraft was reoriented so that the array is warmer, and the team found that the vibration is not present. The team will re-evaluate further redeployment activities once the updates to the controller are checked out on the spacecraft.

In other words, engineers have decided to halt further deployment attempts until they understand fully the cause of this vibration.

At present, the spacecraft is in good health, and the array, only a few degrees short of full deployment, is producing more than 90% of its expected power, more than enough to run the full mission.

Lucy’s view of the Earth-Moon system during its October fly-by

The Earth and Moon system, as seen by Lucy
Click for original image.

Lucy's planned route
Lucy’s planned route to explore the Trojan asteroids

In the days prior to its October 16, 2022 fly-by of the Earth, the Lucy asteroid probe took several calibration images of the Earth and the Moon. The photo above, cropped, reduced, and enhanced to post here, shows both the Earth and the Moon together. From the caption:

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.

In the original, the Moon is so dim, compared to the Earth, that it was hard to find in the picture. I therefore brightened it considerably more than the Earth to make it easily seen above.

Lucy to fly past Earth on October 16th

Lucy solar panel graphic
Artist’s impression of solar panel

As part of its planned route to get to the Trojan asteroids in Jupiter’s orbit, the planetary probe Lucy is scheduled to fly only 220 miles above the Earth’s surface on October 16th.

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.”

That solar array remains unlatched (as shown in the graphic above), but because it is almost completely deployed and is producing about 90% of its intended electricity, engineers have ceased efforts to complete deployment and latching.

Lucy science team ends attempt to deploy solar array

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.

Lucy solar panel almost completely open

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.

Lucy gets a bonus asteroid during its tour of the Trojans

Lucy's planned journey
Click for full image.

While doing observations in March of one of the eight asteroids the Lucy asteroid will visit in the two Trojan asteroid regions fore and aft of Jupiter, scientists discovered it had a companion, thus increasing the total asteroids to be seen close-up by Lucy to nine.

One of the Trojan asteroids on Lucy’s tour, named Polymele, has a companion. Scientists discovered an apparent satellite of Polymele during a ground-based occultation observation in March, when Polymele briefly passed in front of a star, temporarily blocking its light from reaching Earth. The occultation observations were intended to help the Lucy science team determine the shape of Polymele, which only appears as a point of light in telescope images.

“We got a really nice projected shape of Polymele, and then we were very surprised to detect an object about 200 kilometers (120 miles) away from Polymele,” Levison said last week in a presentation to NASA’s Small Bodies Advisory Group. “It’s 5 kilometers (3 miles) in diameter, and it’s sitting almost exactly in Polymele’s equatorial plane.”

Lucy’s science team has temporarily named the object Shaun, after “Shaun the Sheep” in the show “Wallace and Gromit.”

The graphic above, from the Lucy science team, shows the spacecraft’s planned journey during its mission.

Engineers continue their attempts to fully open one of Lucy’s two solar arrays. On June 9th they successfully used the array’s deployment motors again for a short burst to further open the array. The plan is to repeat these short bursts with the hope the array will eventually latch into its intended open position.

Progress in completing the deployment of one of Lucy’s solar panels

Lucy solar panel graphic
Artist’s impression of solar panel

In the past month engineers for the Lucy asteroid mission have conducted a series of successful short tests to see if they can complete the unfolding of one of the probe’s two large solar panels.

On May 9, the team commanded the spacecraft to operate the array’s deployment motor using both the primary and back-up motor windings simultaneously to generate more torque, i.e. a harder pull. The motor operated as expected, further reeling in the lanyard that pulls the solar array open. After running the motor for a series of short intervals to avoid overheating, the team paused to analyze the results. Data from the spacecraft showed that the deployment was proceeding similarly to engineering ground tests, allowing the team to move forward with the second stage of the attempt. Analysis of the data also suggested that there was still additional lanyard to be retracted. The team sent the same commands again on May 12. Although this series of commands did not latch the solar array fully open, it did advance the deployment enough to increase the tension that stabilizes the arrays as was hoped.

On May 26, the spacecraft was again commanded to deploy the solar array. As in the first two attempts, both motor windings were operated simultaneously for short periods of time to avoid overheating. Afterwards the team again analyzed the data from the event, which again showed that the array was continuing to open. The team repeated the deployment command sequence a fourth time on June 2. While the array still did not latch, the data indicates that it continued to further deploy and stiffen throughout the attempt.

The graphic above illustrates the problem. The engineers will attempt further windings, and still hope the panel will open entirely and latch. If not, the stiffening suggests the panel will still stabilize in this open position, which up to now has been sufficient to produce about 90% of the power predicted and enough to complete the mission.

Lucy team schedules attempt to complete solar panel deployment

Lucy solar panel graphic
Artist’s impression of solar panel

After months of discussions, the engineering team of the Lucy asteroid probe have now scheduled the week of May 9th as when they will begin their attempt to complete the deployment of the spacecraft’ partly opened solar panel.

The team is now preparing to complete the solar array deployment in two steps. The first step, tentatively scheduled for the week of May 9, is intended to pull in most of the remaining lanyard and verify that flight results are consistent with ground testing. This step will also strengthen the array by bringing it closer to a fully tensioned state. Because this step is designed to be limited in duration, the array is not likely to latch at that point.

If this step goes as planned, the second step will continue the array deployment with the intent to fully latch. Information gleaned from the first part will help fine-tune the second. The second step is currently planned for a month after the initial one, giving engineers enough time to analyze the data seen in the first attempt.

When launched in October 2021 one of Lucy’s two large solar panels did not completely open and latch, as shown above. Though the spacecraft is presently getting 90% of its expected power, the scientists want to get the panel fully open and latched to insure it will function as planned once the spacecraft gets out to the asteroid belt, where sunlight is dimmer.

Lucy update: cause of solar array issue identified

Lucy solar panel graphic

According to the principal scientist for the Lucy asteroid mission, engineers think they have identified what caused one of Lucy’s two fanlike solar arrays to fail to deploy completely.

The +Y array, rather than unfurling a full 360 degrees, instead went 347 degrees. In that configuration, the spacecraft is still generating more than 90% of its expected power. “Power is not an issue for the spacecraft, nor will it be through the entire mission if we have to fly it like it is.”

The arrays unfurl when a motor pulls on a lanyard, swinging one end of the array around and into place. Levison said that the most likely reason the array did not latch is that, for some reason, there was a loss of tension in the lanyard during deployment. That caused it to fall off a spool and wrap around the motor shaft. About 75 centimeters of lanyard remains to be pulled in.

It appears they in April will turn on the array’s motor to try to pull the lanyard in that last little bit. If that doesn’t work, they will then simply leave things as they are, as it appears the array is open enough to give them sufficient power for their mission.

There are risks to that course, however. Because the array is not latched open, it could begin to close, and thus result in less power to the spacecraft. Furthermore, its unlatched state appears to make some planned engine burns too risky.

Lucy update: Engineers testing solar panel fix on ground

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.

NASA issues vague update on Lucy’s solar panel deployment issue.

Lucy solar panel graphic

NASA today released a very vague update describing the work of the Lucy engineering team in trying to work out a fix to the incomplete deployment of one of Lucy’s solar panels.

A project team completed an assessment Dec. 1 of the ongoing solar array issue, which did not appear to fully deploy as planned after launch in late October. Initial ground tests determined additional motor operations are required to increase the probability of the latching Lucy’s array in place as intended, and the team has recommended additional testing.

Spacecraft operations included discharging and charging the battery while pointed at Earth, moving the spacecraft to point to the Sun, operating the solar array motor with the launch day parameters, moving back to pointing at Earth, and then another battery discharge and recharge. The solar arrays charge the batteries, then the batteries are deliberately discharged, and the solar array circuits are used to recharge the batteries; performing these charging and discharging processes gives the team more information about the solar array circuits.

The team gathered information on two of the 10 gores – the individual solar array panel segments that make up the full array — that previously had no data. NASA now has data on all 10 gores confirming they are open, producing power as expected, and not stuck together. [emphasis mine]

Apparently they have been doing a variety of testing of the array to assess its precise condition. The highlighted words are the most important, as this data suggests that all ten fan sections, as shown in the graphic above, are partly open, and that an attempt to fully deploy the solar panel should work.

The Lucy team has apparently decided to approach this work very slowly and cautiously, that they have time to do so as Lucy continues its slow journey to Jupiter’s Trojan asteroids.

Lucy update: Instruments all working, no action yet on solar array

According to an update from the Lucy science team today, they have completed the checkout of the asteroid probe’s instruments, and found them all operating properly. However, no action has yet been taken to try to correct the partially deployed solar panel.

The team has used an engineering model of the solar array motor and lanyard to replicate what was observed during the initial solar array deployment. The test data and findings suggest the lanyard may not have wound on the spool as intended. Testing continues to determine what caused this outcome, and a range of scenarios are possible. The team isn’t planning to attempt to move or further characterize the current state of the solar array deployment before Wednesday, Dec. 1, at the earliest.

It appears the spacecraft is still on its planned course.

Lucy’s solar panel problem could be due to strap

According to the engineering team for the Lucy asteroid mission, they now think the incomplete deployment of one of the probe’s solar panels was caused by a strap.

The joint Anomaly Response Team has been studying the array using an engineering model. Initial tests indicate that the lanyard that pulls out the solar array may not have completed the process successfully; however, it is still uncertain what caused this condition. The team is conducting more tests to determine if this is indeed the case, and what the root cause might be.

An attempt to characterize the array deployment by attempting to move it would occur no earlier than Nov. 16.

Meanwhile, they have been turning on Lucy’s instruments one by one, with everything functioning as planned, except for that one solar panel. The panel however is a serious concern, as the spacecraft is heading out to the orbit of Jupiter, where it will need every inch of solar panel surface area to get enough power to operate. At the moment it appears the panel is deployed somewhere between 75% to 95%.

Update on Lucy: panels generating more than 90% of expected power

According the Lucy science team, the spacecraft’s solar panels are generating more than 90% of the expected power at this stage of the mission, despite the fact that one panel did not deploy completely and has not latched in final position.

“We’re very happy to report that we are getting most of the power we expected at this point in the mission,” said Joan Salute, associate director for flight programs at NASA’s planetary science division. “It’s not 100%, but it is fairly close. So that is great news.’

In an interview with Spaceflight Now, Salute said the power output from the solar arrays appears to be “most likely above 90%” of the expected level of 18,000 watts. “We don’t know if it’s a latch problem, or that it is only partially deployed,” Salute said.

If correct, there is an excellent chance the mission will not be seriously hindered, even if they cannot get the panel fully deployed or latched. At the same time, there are worries about firing Lucy’s main engine for major course corrections with the panel unlatched. The first major course correction is scheduled for mid-November.

The engineers are presently reviewing their data. One option might be to order the spacecraft to re-attempt a full deployment, in the hope that the process will complete during that second attempt.

A Lucy solar panel on Lucy fails to latch properly after deployment

Partly deployed panel

Engineers at Lockheed Martin (the prime contractor) and Northrop Grumann (which built the panels) are now troubleshooting an issue with one of the solar panels on the asteroid probe Lucy, which failed to latch properly after deployment.

The NASA graphic to the right illustrates this issue, though the graphic might not accurately portray the exact circumstance at Lucy. To get more solar power, Lucy’s panels are larger, and thus were designed to unfurl like a fan rather than the more commonly used accordion design. One panel has not completed that unfurling.

NASA’s announcement tries to minimize the issue but this quote from the link makes it clear that this could be a very big problem.

It’s not yet clear whether the array in question is, in fact, fully deployed but not latched in place or whether it did not reach full deployment and is not generating the same amount of power as its counterpart. It’s also not yet clear whether Lucy can safely fire its maneuvering thrusters with an unlatched array.

ULA’a Atlas-5 successfully launches the Lucy asteroid probe

ULA’a Atlas-5 rocket early this morning successfully launched the Lucy asteroid probe on a 12 year mission to study eight Trojan asteroids over a period from 2025 to 2031. One tidbit about the mission is especially creative:

Scientists named the Lucy mission after the fossilized remains of a human ancestor, called Lucy by the scientists who discovered her in Ethiopia in 1974.

The leaders in the 2021 launch race:

36 China
23 SpaceX
17 Russia
4 Northrop Grumman
4 ULA

The U.S. and China are once again tied in the national rankings, at 36 each.

Biden signs budget continuing resolution, preventing shutdown

At the very last second Congress and President Biden passed and signed another budget continuing resolution that will keep the federal government operating till December and thus preventing another shutdown.

From NASA’s narrow perspective, the action means that the asteroid mission Lucy will likely launch in October as planned. From the perspective of the nation, this last second action merely illustrates the overall failure of the federal government and the elected officials who have been tasked to run it. They are all incompetent, and wouldn’t last five seconds in a real job outside the government.

That the voters keep re-electing them also speaks poorly of America today. We all should be ashamed.

Government shutdown threatens Lucy asteroid mission

Government marches on! The possibility that the federal government could shut down because of the inability of Congress and the Biden administration to pass a funding bill or raise the debt limit now threatens the launch of the Lucy mission to the asteroid belt.

If no budget agreement is reached the government will shut down on October 1st. If the debt limit isn’t raised that shutdown could follow soon thereafter, even if a budget is passed.

The launch window for the mission is from October 16 to November 7, 2021. If the spacecraft does not launch in that window the science team says it will likely require a major rethinking of the entire project, as it will be difficult to find another opportunity to visit the same set of asteroids.

Right now the chances of a shutdown are very high, as the Democrats are pushing big spending bills without any negotiations with the Republicans. In answer, the Republican caucus has said that none of its members will support raising the debt limit. Without the latter any passed spending bill will soon be moot, as the debt limit will soon be reached, blocking further government spending.

Though I personally would be very saddened if Lucy was prevented from launching, that loss would be well compensated for by having the federal government out of business. The evil and corruption promoted by it far outweighs the good work done by several minor space missions.

A Jupiter Trojan asteroid spouts a tail

The ATLAS telescope has discovered the first Jupiter Trojan asteroid to spout a tail like a comet.

Early in June 2019, ATLAS reported what seemed to be a faint asteroid near the orbit of Jupiter. The Minor Planet Center designated the new discovery as 2019 LD2. Inspection of ATLAS images taken on June 10 by collaborators Alan Fitzsimmons and David Young at Queen’s University Belfast revealed its probable cometary nature. Follow-up observations by the University of Hawaiʻi’s J.D. Armstrong and his student Sidney Moss on June 11 and 13 using the Las Cumbres Observatory (LCO) global telescope network confirmed the cometary nature of this body.

Later, in July 2019, new ATLAS images caught 2019 LD2 again – now truly looking like a comet, with a faint tail made of dust or gas. The asteroid passed behind the Sun and was not observable from the Earth in late 2019 and early 2020, but upon its reappearance in the night sky in April of 2020, routine ATLAS observations confirmed that it still looks like a comet. These observations showed that 2019 LD2 has probably been continuously active for almost a year.

While ATLAS has discovered more than 40 comets, what makes this object extraordinary is its orbit. The early indication that it was an asteroid near Jupiter’s orbit have now been confirmed through precise measurements from many different observatories. In fact, 2019 LD2 is a special kind of asteroid called a Jupiter Trojan – and no object of this type has ever before been seen to spew out dust and gas like a comet.

There are a number of mysteries here. First, why should it have suddenly become active, since its orbit is relatively circular (similar to Jupiter’s)? Second, it had been assumed that the Jupiter Trojans had been in their orbits for a long time and had long ago vented any ice on their surfaces. This discovery proves that assumption false. It suggests that either this asteroid is a comet that was recently captured, or that things can happen on these asteroids to bring some buried volatiles up to the surface, where they can then vent.

Above all, this asteroid shows that it is dangerous to assume all Jupiter Trojan asteroids are the same. I guarantee when we finally get a close look at a bunch, when the Lucy mission arrives beginning in 2027, the variety will be quite spectacular.

Probe to visit 8 asteroids, not 7

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.

SpaceX drops protest against NASA launch decision

SpaceX has decided to withdraw its protest against NASA’s decision to choose ULA as the launch vehicle for its Lucy asteroid mission.

The company did not provide any reason for the withdrawal. I suspect Musk decided that it was doing SpaceX harm both publicly and privately. Publicly it threatened the launch date of Lucy, which might cause a significant and fatal delay to the mission. That did not make SpaceX look good to the general public.

Privately, I suspect that the protest was hurting SpaceX with NASA officials. They almost certainly did not say so directly, but I am certain they were able to make this clear in any number of ways. This, combined with the agency’s new willingness to consider commercial rockets, like the Falcon Heavy, for its lunar plans, probably convinced SpaceX that it was doing itself more harm than good with the protest.

ULA gets launch contract for Lucy asteroid mission

Capitalism in space: NASA has awarded ULA a $145 million contract to launch the Lucy asteroid mission on its Atlas 5 rocket.

The price is high for such a launch in today’s market, and is even higher than the cost of some recent military launches, which routinely tack on extra requirements that cause the price to rise. I wonder why. Is it because NASA doesn’t care how much it spends? Or is there a political component here, providing a contract to a company that is having trouble winning contracts in the private sector because their price is too high?

It could be that the mission requires things from the launch that add to the cost. The press release mentions that it “includes the launch service and other mission related costs” but does not specify what they are.

NASA approves two new asteroid missions

NASA has approved two new unmanned missions aimed at studying the asteroids.

Lucy will take a close look at six Trojan asteroids orbiting near Jupiter, after first visiting a main belt asteroid.

Lucy, a robotic spacecraft, is scheduled to launch in October 2021. It’s slated to arrive at its first destination, a main belt asteroid, in 2025. From 2027 to 2033, Lucy will explore six Jupiter Trojan asteroids. These asteroids are trapped by Jupiter’s gravity in two swarms that share the planet’s orbit, one leading and one trailing Jupiter in its 12-year circuit around the sun. The Trojans are thought to be relics of a much earlier era in the history of the solar system, and may have formed far beyond Jupiter’s current orbit.

Psyche will visit 16 Psyche, an unusual metal-rich asteroid made up mostly of iron and nickel.

While Psyche will use an ion engine, allowing it great freedom and even the potential to go elsewhere, like Dawn, when its primary mission is complete, I have not been able to determine whether Lucy will use conventional chemical altitude thrusters or an ion-type engine.