Author Topic: SpaceX F9 : Starlink Group 4-7 : KSC LC-39A : 3 February 2022 (18:13 UTC)  (Read 66279 times)

Offline Rondaz

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Going to *cautiously* estimate arrival around dawn tomorrow.

https://twitter.com/SpaceOffshore/status/1491188361490534400

Online gongora

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https://twitter.com/planet4589/status/1491209847785803777
https://twitter.com/planet4589/status/1491210037569675266

Quote
We've been noticing the lack of orbit updates for the most recent batch of Starlinks, and the reentry of several. Well, it turns out things did not go well for this launch. SpaceX now say increased drag due to a recent geomagnetic storm forced them to put the sats in safemode but

a bunch of them failed to exit safemode and can't orbit raise. So the majority (perhaps 40 of the 49) will reenter shortly after only a few days in orbit

Online gongora

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FEBURARY 8, 2022
GEOMAGNETIC STORM AND RECENTLY DEPLOYED STARLINK SATELLITES
On Thursday, February 3 at 1:13 p.m. EST, Falcon 9 launched 49 Starlink satellites to low Earth orbit from Launch Complex 39A (LC-39A) at Kennedy Space Center in Florida. Falcon 9’s second stage deployed the satellites into their intended orbit, with a perigee of approximately 210 kilometers above Earth, and each satellite achieved controlled flight.

SpaceX deploys its satellites into these lower obits so that in the very rare case any satellite does not pass initial system checkouts it will quickly be deorbited by atmospheric drag. While the low deployment altitude requires more capable satellites at a considerable cost to us, it’s the right thing to do to maintain a sustainable space environment.

Unfortunately, the satellites deployed on Thursday were significantly impacted by a geomagnetic storm on Friday. These storms cause the atmosphere to warm and atmospheric density at our low deployment altitudes to increase. In fact, onboard GPS suggests the escalation speed and severity of the storm caused atmospheric drag to increase up to 50 percent higher than during previous launches. The Starlink team commanded the satellites into a safe-mode where they would fly edge-on (like a sheet of paper) to minimize drag—to effectively “take cover from the storm”—and continued to work closely with the Space Force’s 18th Space Control Squadron and LeoLabs to provide updates on the satellites based on ground radars.

Preliminary analysis show the increased drag at the low altitudes prevented the satellites from leaving safe-mode to begin orbit raising maneuvers, and up to 40 of the satellites will reenter or already have reentered the Earth’s atmosphere. The deorbiting satellites pose zero collision risk with other satellites and by design demise upon atmospheric reentry—meaning no orbital debris is created and no satellite parts hit the ground. This unique situation demonstrates the great lengths the Starlink team has gone to ensure the system is on the leading edge of on-orbit debris mitigation.

Online vaporcobra

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Online JayWee

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Ouch. Do you think they are insured?
How could the atmospheric density prevent the satellites from exitting the safe mode?

Online vaporcobra

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Ouch. Do you think they are insured?
How could the atmospheric density prevent the satellites from exitting the safe mode?

My guess is that that means the force of atmospheric drag is now greater than the thrust Starlink's ion propulsion can produce, making orbit-raising physically impossible. Properly deploying the solar arrays to maximize power generation (probably necessary for max-thrust orbit-raising) would also drastically increase that drag.

Offline kevin-rf

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Since the solar cycle is on the uptick, I wonder if they will offload a few satellites on future launches so they can deploy at a slightly higher altitude.
If you're happy and you know it,
It's your med's!

Offline eeergo

Ouch. Do you think they are insured?
How could the atmospheric density prevent the satellites from exitting the safe mode?

My guess is that that means the force of atmospheric drag is now greater than the thrust Starlink's ion propulsion can produce, making orbit-raising physically impossible. Properly deploying the solar arrays to maximize power generation (probably necessary for max-thrust orbit-raising) would also drastically increase that drag.

There can be several effects at play here: one is the overwhelming of the control authority they are able to muster (i.e. their attitude might have been unstable due to drag making them tumble). They presumably use control rods and gyros for that, perhaps coupled with help from the ion thrusters (?), although the gyros may only be for fine-pointing the optical links.

Then there can be the thrust issue you mention, by itself or in combination with the above (if they can't keep the edge-on attitude well locked, then drag will increase too, making control harder and increasing drag, in a vicious circle)... although that seems unlikely -or a major design flaw- since this extremely quick deorbit would mean they aren't even able to *hold* their current orbit (whose apogee is quite a bit higher than 200-something km), not just raise it. If this minor storm was an issue (50% extra sounds like a lot, but let's keep in mind this means less than twice the drag than previous occasions, which is NOT a lot, especially with this being a well-known and consistently measured effect). Considering we've been going through one of the quietest solar minima on record, it doesn't bode well for the system's deployment over the next few years as the Sun gets rowdy again.

Another issue can be within the electric propulsion itself: too high an ambient free electron density and you will get arcing between the thruster's cathode and its neutralizer, which will fault the EP and can altogether prevent its operation.

Then there are the radiation effects of course (both over the poles and the SAA), although the release doesn't seem to focus on them, and levels don't appear to have significantly increased.

Has anyone seen any news concerning other satellites (in general) and Starlinks (in particular)? There should be >150 S/C undergoing orbit-raising experiencing similar issues - even if not so severe as to bring them down in a matter of hours, there can have been issues with them as well, especially for the 4-6 group launched just a few days prior.

This event has single-handedly doubled early mortality numbers for Starlink.
-DaviD-

Offline jacqmans

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SpaceX photos

Offline eeergo

Ouch. Do you think they are insured?
How could the atmospheric density prevent the satellites from exitting the safe mode?

My guess is that that means the force of atmospheric drag is now greater than the thrust Starlink's ion propulsion can produce, making orbit-raising physically impossible. Properly deploying the solar arrays to maximize power generation (probably necessary for max-thrust orbit-raising) would also drastically increase that drag.

There can be several effects at play here: one is the overwhelming of the control authority they are able to muster (i.e. their attitude might have been unstable due to drag making them tumble). They presumably use control rods and gyros for that, perhaps coupled with help from the ion thrusters (?), although the gyros may only be for fine-pointing the optical links.

Then there can be the thrust issue you mention, by itself or in combination with the above (if they can't keep the edge-on attitude well locked, then drag will increase too, making control harder and increasing drag, in a vicious circle)... although that seems unlikely -or a major design flaw- since this extremely quick deorbit would mean they aren't even able to *hold* their current orbit (whose apogee is quite a bit higher than 200-something km), not just raise it. If this minor storm was an issue (50% extra sounds like a lot, but let's keep in mind this means less than twice the drag than previous occasions, which is NOT a lot, especially with this being a well-known and consistently measured effect). Considering we've been going through one of the quietest solar minima on record, it doesn't bode well for the system's deployment over the next few years as the Sun gets rowdy again.

Another issue can be within the electric propulsion itself: too high an ambient free electron density and you will get arcing between the thruster's cathode and its neutralizer, which will fault the EP and can altogether prevent its operation.

Then there are the radiation effects of course (both over the poles and the SAA), although the release doesn't seem to focus on them, and levels don't appear to have significantly increased.

Has anyone seen any news concerning other satellites (in general) and Starlinks (in particular)? There should be >150 S/C undergoing orbit-raising experiencing similar issues - even if not so severe as to bring them down in a matter of hours, there can have been issues with them as well, especially for the 4-6 group launched just a few days prior.

This event has single-handedly doubled early mortality numbers for Starlink.

The issue was primarily the temporary increase of up to 50% in atmospheric density at the deployment altitude. Even so, some of the current batch managed to navigate through it.

Everything at a higher altitude will be fine. No need for opportunistic concern trolling.👍

Appreciate your rapid knee-jerk and name calling, with no actual meaningful discussion of the issue or the informed hypotheses presented.👍 Forgot no problem can be discussed in these sections for some here, even when >80% of a mission's payload is toast a few hours after launch, due to a relatively common and mild event.

By the way, regarding higher altitudes being "fine". Apart from the fact there is no specific information to base that assertion on, a 1.5x increase of drag at 200-odd km is NOT a lot, as I said before. Along-track drag conditions at a given altitude in LEO can easily reach integer multiples of their value at solar minimum (which is where Starlink has been operating so far): think factors of 4-7x even at 500 km. FYI, this information is actually based on industry-standard operational-level atmospheric models.
« Last Edit: 02/09/2022 08:01 am by eeergo »
-DaviD-

Offline Rondaz

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Falcon 9 Booster B1061 arriving into Port Canaveral on "A Shortfall Of Gravitas".

Looks like it used up a lot of crush core. That can be replaced.

https://twitter.com/NASASpaceflight/status/1491299776243322883

Offline Rondaz

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Offline Rondaz

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Horrible photo, but looks like B1061 is on jack stands.  It is so dark I had to shoot at 51k iso to get this photo and I was just at the limits of my camera body.

https://twitter.com/Kyle_M_Photo/status/1491305904544772098

Offline Rondaz

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Offline envy887

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Has anyone seen any news concerning other satellites (in general) and Starlinks (in particular)? There should be >150 S/C undergoing orbit-raising experiencing similar issues - even if not so severe as to bring them down in a matter of hours, there can have been issues with them as well, especially for the 4-6 group launched just a few days prior.

This event has single-handedly doubled early mortality numbers for Starlink.

jcm updated his plots with data through yesterday for the previous 3 launches (4-4, 4-5, and 4-6) , and they all look like they are continuing to operate normally. "Normally" means raising to ~350 km, which starts within 36 hours of launch, and then drifting to precess until they are in plane to continue raising. There are plenty of sats both drifting and raising as of yesterday, and it all looks nominal.

The 4-7 batch are now 9 days post-launch and never started the L+36 hour raise. They are clearly behaving much differently then the previous 3 launches. I don't think there's anything here to worry about for the earlier launches.

https://planet4589.org/space/stats/star/starstats.html

Offline AstroDave

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From this perspective the engine bells on 1061 look unharmed. Hope it is just crush cores that need replacing.

Offline eeergo

Has anyone seen any news concerning other satellites (in general) and Starlinks (in particular)? There should be >150 S/C undergoing orbit-raising experiencing similar issues - even if not so severe as to bring them down in a matter of hours, there can have been issues with them as well, especially for the 4-6 group launched just a few days prior.

This event has single-handedly doubled early mortality numbers for Starlink.

jcm updated his plots with data through yesterday for the previous 3 launches (4-4, 4-5, and 4-6) , and they all look like they are continuing to operate normally. "Normally" means raising to ~350 km, which starts within 36 hours of launch, and then drifting to precess until they are in plane to continue raising. There are plenty of sats both drifting and raising as of yesterday, and it all looks nominal.

The 4-7 batch are now 9 days post-launch and never started the L+36 hour raise. They are clearly behaving much differently then the previous 3 launches. I don't think there's anything here to worry about for the earlier launches.

https://planet4589.org/space/stats/star/starstats.html

Thanks for the link! Indeed, looks like the orbit-raising process to the intermediate altitude takes about three weeks, which the 4-6 batch had just spent in orbit at the time of the storm.
« Last Edit: 02/09/2022 01:30 pm by eeergo »
-DaviD-

Offline Rondaz

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ASOG returned overnight with B1061 completing its sixth flight and the Starlink 4-7 mission. The southern trajectory makes for some high energy landings resulting in crush core use and old school chains to secure the booster.

https://twitter.com/julia_bergeron/status/1491399355143962636

Offline Rondaz

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Last night, booster 1061-6 returned on ASOG after launching Starlink 4-7.

https://twitter.com/JennyHPhoto/status/1491394472927965187

Offline rsnellenberger

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The solar event (a Coronal Mass Ejection) that caused the geomagnetic storm occurred on January 31.  NOAA issued its geomagnetic storm warning for February 2/3 the evening before the launch.

It sounds like SpaceX just learned a very expensive process lesson.

https://www.swpc.noaa.gov/news/geomagnetic-storm-conditions-likely-2-3-february-2022

Edit: spelling
« Last Edit: 02/09/2022 02:33 pm by rsnellenberger »

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