Author Topic: NASA - Lucy - (Trojan Asteroid Flyby) - Updates and Discussion  (Read 101903 times)

Offline Welsh Dragon

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Personally I'm  mystified why someone wouldn't be excited about this mission. Far more exciting to me than yet another Mars mission.

Offline daedalus1

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Personally I'm  mystified why someone wouldn't be excited about this mission. Far more exciting to me than yet another Mars mission.

Probably because there is more varied geology on Mars. And there is a realistic possibility of humans walking on Mars.
So yo don't have to be mystified any more.

Online vjkane

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The Lucy science team published a paper detailing the missions overarching goal and then specific measurements to support that goal.

The mission's key goal is to establish that there is a diversity and relate the bodies to possible origin locations. While there will be observations related to specific body evolutions, that's not the primary goal of the mission.

Also, there was a mention below of a possible extended mission. The PI has stated that the spacecraft can continue to cycle through the asteroid belt and the Trojan populations. I believe he mentioned that they had identified something like 20 candidate objects, of which on Psyche was specifically named.  He also noted that this would no longer be a priority extended target for obvious reasons. The limitation on the extended mission will be the fuel since targeting a specific body requires a fair amount of fuel.

The mission's scientific goal from the paper: "The Trojan asteroids were long thought to be a population that formed near Jupiterʼs orbital distance, representing the composition of the nebula near that location. Thus, it is a surprise that Earth-based observations show that they are different from one another  This unexpected diversity may be understood in the context of a class of models developed within the last 15 yr or so, which suggest that the objects currently found in the Trojan swarms were originally formed far beyond their current home (at ∼15–30 au), and were transported to their current locations by early orbital evolution of the giant planet orbit… These models suggest that the observed diversity of Trojans is the result of the fact that they originated over a large range of heliocentric distances with varying physical and compositional conditions. Understanding the diversity of Trojans, by interrogating as many observables as possible, will allow us to determine whether these ideas are true, and if true, allow us to constrain the orbital evolution of the giant planets. If Lucy proves these ideas incorrect, it will provide vital clues to develop new hypotheses. "

The paper is open access and available here: https://iopscience.iop.org/article/10.3847/PSJ/abf840/meta

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Offline Rondaz

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Lucy Spacecraft Healthy; Solar Arrays Being Analyzed

Karen Fox Posted on October 17, 2021

Following a successful launch on Oct. 16, 2021, analysis of NASA’s Lucy spacecraft systems show the spacecraft is operating well and is stable. 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. The team is analyzing spacecraft data to understand the situation and determine next steps to achieve full deployment of the solar array.

https://blogs.nasa.gov/lucy/2021/10/17/lucy-spacecraft-healthy-solar-arrays-being-analyzed/

Offline Rondaz

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The Lucy probe is now 820,000 km from Earth, still inside the Sun-Earth Hill sphere where Earth's gravity is more important than solar gravity

https://twitter.com/planet4589/status/1449923233927639047

Offline abaddon

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Arstechnica article on the latch issue: https://arstechnica.com/science/2021/10/lucys-solar-panel-hasnt-latched-a-problem-for-a-mission-powered-by-the-sun/.

Any informed thoughts on what a latch failure might mean, if they are unable to correct it?

Offline abaddon

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Personally I'm  mystified why someone wouldn't be excited about this mission. Far more exciting to me than yet another Mars mission.
I'm mystified when I got to a modern art museum why a blank canvas is worth more than I will make in my lifetime.  Different strokes for different folks, but I don't really see a need to "wonder" why my preferences aren't the preferences of others.

(I definitely find the prospect of the discoveries from this mission exciting, for the record).

Offline redliox

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Sadly this reminds me of how Galileo's main antenna couldn't deploy, but I am at least glad only one of the arrays, not both, is afflicted by this so the mission isn't ruined.  Hopefully coming developments resolve/minimize the affected array's problem.
"Let the trails lead where they may, I will follow."
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Offline ccdengr

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Any informed thoughts on what a latch failure might mean, if they are unable to correct it?
If there's negligible reduction of power production, possibly no impact.  Mars Global Surveyor flew its whole mission with an unlatched solar array, though it impacted the depth of aerobraking and made orbit lowering take longer.  (Obviously a different array design.)

I can't tell if the Ultraflex array can reverse the deployment drive motor or not.  Here's an old paper but I don't know how the specifics may have changed.  https://ntrs.nasa.gov/api/citations/19940006927/downloads/19940006927.pdf

If there is a big hit on power, it could probably be managed by taking longer to play data back to allow more recharge time between comm sessions.  I assume they don't rely on array power during an actual flyby, being able to run off batteries, but I don't know how the batteries are sized.
« Last Edit: 10/18/2021 03:32 pm by ccdengr »

Offline Hungry4info3

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My main concern is if the solar array is out there dangling, how much is that going to be an issue for instrument pointing stability? Fortunately this spacecraft has a scan platform that can move independently, so I hope it won't be too much.

Online Phil Stooke

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I don't know any more than is public, but I note that they say one did not fully latch, not that it did not fully open. 

Online edzieba

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My main concern is if the solar array is out there dangling, how much is that going to be an issue for instrument pointing stability? Fortunately this spacecraft has a scan platform that can move independently, so I hope it won't be too much.
Depending on what "did not fully latch" entails (completely loose and flapping in the solar breeze? Only single lock engaged? Seated but not latched?) there could be limits placed on thruster firings to reduce force applied to the array to minimise the chance of unintentionally re-closing the array (e.g. no rapid starts/stops to rolls). That could potentially impact pointing during flybys at close ranges, leading to more distance flybys being chosen or loss of observation during the start or end of a flyby due to maximum rotation rate limits being imposed.
On the other hand, depending on what exactly went wrong with the the latching there's the chance and 'angles and dangles' could be performed to attempt to reseat the panel and give another opportunity for the latches to close. That comes at risk to the mission if it results in the array ending up in an unlatch but less open state than it is currently in.
More analysis of the exact state of the array is needed first.

Offline Zed_Noir

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....
Fortunately this spacecraft has a scan platform that can move independently
....


Wonder if the scan platform can imaged the solar array with the latch issue?


Online meekGee

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Personally I'm  mystified why someone wouldn't be excited about this mission. Far more exciting to me than yet another Mars mission.

Probably because there is more varied geology on Mars. And there is a realistic possibility of humans walking on Mars.
So yo don't have to be mystified any more.
There seems plenty of variety in geology of asteroids. To me manned missions to an asteroid are actually more viable than going to Mars. TBH the more I hear about the difficulties in getting to Mars especially on the health side I am starting to wonder if going to an asteroid after the Moon might not be a better option for now.
Are we seriously doing this here?

Note the previous poster explained why some people are interested.  You OTOH are starting a full blown argument over Moon vs Mars vs Asteroids.   Nobody even mentioned the moon beforehand.

Done preaching.
« Last Edit: 10/19/2021 10:46 pm by meekGee »
ABCD - Always Be Counting Down

Offline deadman1204

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....
Fortunately this spacecraft has a scan platform that can move independently
....


Wonder if the scan platform can imaged the solar array with the latch issue?
no, there are no cameras set up to image the spacecraft itself.

Offline Star One

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Personally I'm  mystified why someone wouldn't be excited about this mission. Far more exciting to me than yet another Mars mission.

Probably because there is more varied geology on Mars. And there is a realistic possibility of humans walking on Mars.
So yo don't have to be mystified any more.
There seems plenty of variety in geology of asteroids. To me manned missions to an asteroid are actually more viable than going to Mars. TBH the more I hear about the difficulties in getting to Mars especially on the health side I am starting to wonder if going to an asteroid after the Moon might not be a better option for now.
Are we seriously doing this here?

Note the previous poster explained why some people are interested.  You OTOH are starting a full blown argument over Moon vs Mars vs Asteroids.   Nobody even mentioned the moon beforehand.

Done preaching.
Original post removed as I mistakenly thought I was in the discussion not updates thread. IMHO though all these posts seem OT for this thread.

Offline tyrred

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Yeah this thread has great discussion, but does not adhere to what some would expect from an update thread. Which thread is the discussion thread, again?

Lucy is one of the more intriguing missions to me, and I would just like to know more TM.

Offline fast

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My main concern is if the solar array is out there dangling, how much is that going to be an issue for instrument pointing stability? Fortunately this spacecraft has a scan platform that can move independently, so I hope it won't be too much.
Depending on what "did not fully latch" entails (completely loose and flapping in the solar breeze? Only single lock engaged? Seated but not latched?) there could be limits placed on thruster firings to reduce force applied to the array to minimise the chance of unintentionally re-closing the array (e.g. no rapid starts/stops to rolls). That could potentially impact pointing during flybys at close ranges, leading to more distance flybys being chosen or loss of observation during the start or end of a flyby due to maximum rotation rate limits being imposed.
On the other hand, depending on what exactly went wrong with the the latching there's the chance and 'angles and dangles' could be performed to attempt to reseat the panel and give another opportunity for the latches to close. That comes at risk to the mission if it results in the array ending up in an unlatch but less open state than it is currently in.
More analysis of the exact state of the array is needed first.

Is there any photos of spacecraft exterior after arrays deployment?

Online edzieba

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New update: https://blogs.nasa.gov/lucy/2021/10/19/nasa-team-remains-focused-on-lucys-solar-arrays/

Quote
After successful separation from the rocket on Oct. 16, NASA’s Lucy spacecraft deployed both solar arrays. Soon after deployment, NASA received confirmation that one of the solar arrays was fully deployed and latched. Analysis currently shows the second solar array is partially unfurled. The team continues to look at all available engineering data to establish how far it is deployed. That solar array is generating nearly the expected power when compared to the fully deployed wing. This power level is enough to keep the spacecraft healthy and functioning.

The Lucy spacecraft has remained in safe mode and is transitioning to cruise mode today. This mode has increased autonomy and spacecraft configuration changes, which is necessary as Lucy moves away from Earth. The team continues its assessment and an attempt to fully deploy the solar array is planned no earlier than the end of next week.

Lucy has successfully fired thrusters to slew the spacecraft with the current array configuration and will safely continue with desaturation maneuvers — small thruster firings to manage the spacecraft’s momentum — as planned.

The operations team has temporarily postponed the deployment of the instrument pointing platform to focus on resolving solar array deployment. The operations team continues to execute all other planned post-launch activities. The ULA Atlas V rocket delivered Lucy precisely to the target point at separation, and so a backup maneuver called the Trajectory Correction Maneuver (TCM-1) is unnecessary and has therefore been canceled. The first maneuver will now be what’s known as TCM-2, currently scheduled for mid-December.

The project is evaluating whether there are any long-term implications to other scheduled activities.

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