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Raumfahrt - ESA/NASA Lucy asteroid probe Mission -Update 1

19.10.2021

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NASA investigating issue with Lucy solar array

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WASHINGTON — Engineers are investigating why one of the two solar arrays on NASA’s Lucy spacecraft may have failed to lock into place when deployed after launch Oct. 16.

In an Oct. 17 statement, NASA said that while the spacecraft is healthy, one of the two circular solar panels “may not be fully latched” after its deployment. The solar arrays deployed in the first half-hour after separation from the Centaur upper stage of the Atlas 5 rocket that launched it early Oct. 16.

Both solar panels are generating power, the agency stated, and there are no other problems with the spacecraft. “In the current spacecraft attitude, Lucy can continue to operate with no threat to its health and safety,” NASA said in the statement. “The team is analyzing spacecraft data to understand the situation and determine next steps to achieve full deployment of the solar array.”

“This team has overcome many challenges already and I am confident they will prevail here as well,” Thomas Zurbuchen, NASA associate administrator for science, tweeted Oct. 17.

Lucy’s two solar panels are each 7.3 meters in diameter. Stored in a folded configuration, they were designed to unfurl “like Chinese fans,” said Joan Salute, associate director for flight programs in NASA’s planetary science division, at a prelaunch briefing Oct. 14.

The arrays have a combined 51 square meters of solar cells. That large area is needed since the spacecraft will be flying out to Jupiter’s distance from the sun, where the sunlight is only a few percent as powerful as at Earth. “That enables Lucy to travel further away from the sun than any other solar-powered spacecraft to date,” said Katie Oakman, Lucy structures and mechanisms lead at Lockheed Martin Space, at the Oct. 14 briefing. Lockheed was the prime contractor for Lucy, although the solar arrays were built by Northrop Grumman.

In the vicinity of the Earth, Lucy’s panels can generate 18 kilowatts of power. However, when flying by the Trojan asteroids that are the destination of the mission, the arrays will produce only 500 watts of power, still sufficient to operate the spacecraft and its three main instruments.

She added there was no specific design requirement for circular arrays versus more conventional rectangular ones, but that those offered the most area while fitting in the confines of the Atlas payload fairing. “This particular design really enables us to stow up closely and tightly next to the spacecraft for launch,” she said. “Having any particular shape other than this really unique design wouldn’t enable us to get to that 51-meter-squared of active cell area and still fit within the launch vehicle fairing.”

It’s unclear if the problem will affect other work to check out the spacecraft after its launch. That includes deployment of the instrument pointing platform, on which the three major instruments are mounted, which is scheduled for about two days after launch.

Quelle: SN

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NASA studying solar array issue with Lucy asteroid probe

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NASA's $1 billion Lucy asteroid probe is safely on its way, but engineers are studying telemetry indicating one of its two circular solar arrays may not be fully deployed and latched in place, the agency said in a blog post Sunday.

Lucy was launched from Cape Canaveral early Saturday atop a United Launch Alliance Atlas 5 rocket and released on a trajectory setting up two velocity-boosting gravity-assist Earth flybys in 2022 and 2024 to fling the craft out to a swarm of asteroids sharing Jupiter's orbit.

A third Earth flyby is planned for 2030 to send the craft to a pair of asteroids in another "Trojan" swarm in 2033.

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Two frames from a computer animation produced by NASA's Goddard Space Flight Center show how the Lucy asteroid probe's two solar arrays are designed to unfold in a circular fashion. Telemetry indicates one of the two arrays may not have locked in the fully open position after launch Saturday.NASA
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NASA

Built by Lockheed Martin Space, Lucy will be operating farther from the sun than any other solar-powered spacecraft before it, and its two Northrop Grumman-built arrays, designed to unfold 360 degrees like Chinese fans, are critical to mission success.

Shortly after launch Saturday, NASA confirmed both 24-foot-wide arrays had deployed and were generating power. But on Sunday, the agency said one of the arrays may not be latched in place.

"Following a successful launch ... analysis of NASA's Lucy spacecraft systems show the spacecraft is operating well and is stable," the blog post said. "Lucy's two solar arrays have deployed, and both are producing power and the battery is charging."

"While one of the arrays has latched, indications are that the second array may not be fully latched. All other subsystems are normal. In the current spacecraft attitude, Lucy can continue to operate with no threat to its health and safety."

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An artist's impression of the Lucy probe as it flies past a Trojan asteroid.NASA

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.

Thomas Zurbuchen, NASA's science chief, said he was confident engineers will resolve the problem.

"The two solar arrays have deployed, but one may not be fully latched," he tweeted. "The team is analyzing data to determine next steps. This team has overcome many challenges already and I am confident they will prevail here as well."

Whether intentional or not, Zurbuchen's tweet included a frame from the Goddard animation above showing one array fully deployed and one with a gap indicating a partial deployment.

Quelle: CBS News

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Update: 20.10.2021

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NASA officials optimistic Lucy asteroid mission will overcome solar array snag

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Artist’s illustration of the final phase of deploying the solar arrays on NASA’s Lucy spacecraft. Credit: NASA

A NASA official said Monday there is “widespread optimism” that a solar array snag discovered on the Lucy asteroid probe after its launch over the weekend will not jeopardize the spacecraft’s 12-year exploration mission.

Lucy’s two solar arrays were folded up on each side of the box-shaped spacecraft during launch Saturday from Cape Canaveral aboard an Atlas 5 rocket. One of the two solar array wings fully unfurled and latched after launch, but NASA says it did not receive confirmation that the other wing latched into place.

The Atlas 5 deployed the Lucy probe nearly an hour after liftoff, sending the 3,300-pound (1,500-pound) spacecraft on an escape trajectory into the solar system. The launch kicked off a $981 million mission to explore the Trojan asteroids, a primordial population of small worlds leading and trailing Jupiter in its orbit around the sun.

Lucy is the mission is the first to explore the Trojan asteroids, which scientists say are leftover building blocks similar to objects that came together to form the solar systems giant outer planets. The probe will fly by seven Trojan asteroids between 2027 and 2033, plus one object in the main asteroid belt in 2025.

A few minutes after separating from the Atlas 5 launcher, Lucy began a pre-programmed sequence to unfold the solar arrays like giant Chinese fans. Fully deployed, the UltraFlex solar wings span about 24 feet (7.3 meters) in diameter, the circular power arrays to ever fly in space.

Both solar arrays are generating power, and Lucy’s batteries are fully charged, said Lori Glaze, director of NASA’s planetary science division.

“The spacecraft is stable and healthy, and it’s safe,” Glaze said Monday in a virtual town hall meeting by NASA’s science mission directorate. “It’s not in any danger, at this point, in this configuration. So we are taking our time in determining what’s going on with the solar array, and developing a path forward on how to remediate.”

“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.

Lucy will become the farthest spacecraft from the sun to ever rely on solar power, reaching a maximum distance of 530 million miles (853 million kilometers), nearly six times farther than Earth’s orbit. When it reaches the Trojan asteroids, Lucy’s solar arrays were expected to generate just 500 watts of power.

That level power output is sufficient to feed Lucy’s three science instruments, which only need about 82 watts of power during each asteroid encounter. Lucy’s flight computer, communications system, and other components will also draw on power generated by the UltraFlex arrays.

Salute said controllers may attempt to command Lucy to re-attempt a full deployment of the solar array.

“They’re checking different analyses, making sure that that would be safe to implement,” she said. “One of the steps that they would be taking in the fairly short term would be to provide a second attempt at full deployment and latching.”

The UltraFlex solar arrays on NASA’s Lucy spacecraft unfold during a ground test at a Lockheed Martin test facility in Colorado. Credit: Lockheed Martin

Lockheed Martin, the prime contractor for the Lucy spacecraft, oversees mission operations from a control center near Denver.

Although the solar arrays are generating sufficient power, engineers are also evaluating whether it is safe to fire the spacecraft’s main engine with an unlatched solar array. The mission’s first major deep space maneuver is tentatively scheduled for mid-November.

“At this point in time, they hope to go ahead with that maneuver, but it is too early to tell,” Salute said.

The spacecraft has continued firing its smaller attitude control thrusters without any issues, she said.

“They just want to really get a little more understanding under their belt about which would be safer — to re-deploy or to operate as is,” Salute said. “And I don’t think they have a firm answer on that option quite yet.”

Managers have postponed one other major post-launch activity to allow engineers to address the solar array issue. Lucy’s instrument platform was supposed to release and deploy two days after launch. That has been temporarily put on hold, according to Salute.

“There’s still widespread optimism that this can be overcome, or worked with,” Salute said.

Quelle: SN

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Update: 10.12.2021

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NASA Zeroing in on Path Forward for Lucy Solar Array

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NASA plans to conduct additional ground tests on an engineering model of the Lucy solar array motor and lanyard prior to potentially attempting full deployment of one of the probe’s solar arrays.
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.
These activities are helping the agency create a robust plan for attempting to fully deploy the array. Additional ground tests using the engineering model setup will validate a two-motor attempt for full deployment. NASA currently is creating a schedule and the resources needed to support that effort, as well as continuing to study the possibility of leaving the array as is.

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Lucy Instruments Checkout A-OK

 

NASA’s Lucy spacecraft continues to operate in cruise mode – the standard mode for its orbit away from Earth.
Checkouts for the Lucy instruments were successfully completed Nov. 8, and all instruments are working normally. Following checkout completion, the instruments were powered off, and the remaining spacecraft subsystem commissioning activities are continuing as scheduled.
Lucy’s Solar Array Anomaly Response Team has made progress searching for the cause of the solar array’s incomplete deployment. 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.

Quelle: NASA

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Update: 27.01.2022

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Cause of Lucy solar array deployment problem identified

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WASHINGTON — Engineers have identified the likely reason one of two solar arrays on NASA’s Lucy asteroid mission failed to latch in place after launch, but NASA is still studying whether to fix the problem.

At a Jan. 25 meeting NASA’s Small Bodies Assessment Group, Hal Levison, principal investigator for Lucy at the Southwest Research Institute, expressed confidence that, regardless if the solar array is fully deployed or not, the issue will not affect the spacecraft’s ability to carry out its mission to study several Trojan asteroids leading and following Jupiter in its orbit around the sun.

Shortly after its Oct. 16 launch, deployed two large circular solar arrays, each 7.3 meters in diameter. The arrays are designed to unfurl like fans and latch into place. While one array, called -Y, did completely unfurl and latch, the other, +Y, did not latch into place.

“People have been working day and night since the launch to try and figure out what’s going on, and I think we understand it,” Levison said. 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 matches the data really well, so we have really high confidence this is true,” he said. One possible cause of the loss of tension, he added, is a “dynamic interaction” between the two arrays during the deployment.

Mission managers are considering two alternatives. One is to turn the motors back on and try to bring in the remaining lanyard segment so that the array can lock into place. “We’re almost there, so I think if we can pull a little harder, we might be able to get it to latch,” he said. The motor can pull harder, he said, but engineers want to assess the risks of doing so before making another attempt.

The other option is to keep the array as is. While the array can generate enough power without being fully deployed, Levison said engineers want to study its integrity in that configuration during main engine burns. “The analysis so far is looking good. We should be able to do at least some of the main engine burns we’re planning.”

There’s no rush to decide whether to redeploy the array or leave it as is. “We have plenty of time because we’re not scheduled to fire the main engine for a while,” he said. “We’re taking our time to carefully go through our options.”

That assessment matches the most recent NASA update about the mission, published Jan. 12. It stated that the current plan for the mission “supports a latch attempt in the late April timeframe” but that engineers were still studying leaving the array in its current unlatched condition.

Levison added that all other aspects of the spacecraft, including its instruments, were working well. “Except for this problem, the spacecraft is really kicking butt,” he said. “The instruments and the spacecraft are all behaving nominally.”

Quelle: SN

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Update: 24.04.2022

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Lucy is "Go" for solar array deployment attempt

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On April 18, NASA decided to move forward with plans to complete the deployment of the Lucy spacecraft's stalled, unlatched solar array. The spacecraft is powered by two large arrays of solar cells that were designed to unfold and latch into place after launch. One of the fan-like arrays opened as planned, but the other stopped just short of completing this operation.

Through a combination of rigorous in-flight solar array characterization and ground testing, Lucy engineers determined the unlatched solar array is nearly fully open, positioned at approximately 345 out of the full 360 degrees, and is producing ample energy for the spacecraft. Nonetheless, the team is concerned about potential damage to the array if the spacecraft conducts a main engine burn in its present configuration.

After launch, the arrays were opened by a small motor that reels in a lanyard attached to both ends of the folded solar array. The team estimates that 20 to 40 inches of this lanyard (out of approximately 290 inches total) remains to be retracted for the open array to latch.

The solar array was designed with both a primary and a backup motor winding to give an added layer of reliability for the mission-critical solar array deployment. Lucy engineers will take advantage of this redundancy by using both motors simultaneously to generate higher torque than was used on the day of launch. Ground tests show that this added torque may be enough to pull the snarled lanyard the remaining distance needed to latch.

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.

Quelle: SD 

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NASA's Lucy asteroid probe will watch the Super Flower Blood Moon eclipse from deep space

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