Author Topic: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011  (Read 425949 times)

Offline JimO

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #800 on: 11/11/2011 06:53 PM »
Now that the subject of explosions has come up, let me ask this: if F-G remains stuck in its decaying orbit and at least one tank is already venting, what is the likelihood of more leaks leading to a hypergolic mix that triggers a chain reaction of larger and larger explosions?

How much more/less likely is an orbital debris impact that triggers likewise?

If it happens, does the secret US death ray laser get blamed? Or the Chinese one?

If it happens, how energetic could some of the fragments be ejected forward?

That is, could they reach ISS altitude and add to the already pesky Chinese ASAT debris threat?

Is an on-orbit explosion a 'happy ending'?




Offline Art LeBrun

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #801 on: 11/11/2011 06:53 PM »
Solar panels on s/c: they wouldn't be recharging "Fregat" batteries ??? Unless s/c batteries could interlink with escape stage batteries?
« Last Edit: 11/11/2011 06:58 PM by Art LeBrun »
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Offline kevin-rf

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #802 on: 11/11/2011 06:53 PM »
I wonder if we could provide some small summary of where we are, as I really need to get a new article on (as opposed to what is the launch day article currently on site). So I'm going to write a shortish state of play summary and give it a bit of a fresh look by adding NASA's interest in Phobos.

I just need to check what we appear to have as facts - and no more, the thread is for NK comments, speculation, etc:

We had nominal Zenit-2 first and second stage performance.
First - and obviously the second - burn on the Fregat-derived stage did not occur, because the flight computer went into safe mode (reason unknown).
Recovery of the computer has been unsuccessful - partly because of antenna issues (I'm not clear on this element) - during all passes thus far.
They do have more than the three days as the solar panels are extended and sun-facing.
However, it is expected to re-enter at the end of the month if this is a Loss of Mission scenario due to decaying orbit.

Much appreciated if anyone can tick some boxes/correct me - I'd be a fool to not ask and end up making a basic mistake in an article.

Chris to play devils advocate here, since there was no telemetry during the critical events do we know that?

Do we know that the first burn not occurring was due to the computer being in safe mode? Is it possible something else caused the burn to abort and that triggered safemode?
Do we know that the solar panels are extended and sun facing? Based on amateur observers we know the vehicle is stable and not tumbling.
Also did you read Ted Molczan's post ( http://satobs.org/seesat/Nov-2011/0116.html ) that oddly the two TLE's may point to a Delta V of ~1.3   while over Baikonur?

Anywho looking forward to the article.
« Last Edit: 11/11/2011 06:59 PM by kevin-rf »
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Offline kevin-rf

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #803 on: 11/11/2011 06:58 PM »
Jim O, any potential explosion would be in a low orbit and even though it would be energetic and boost some debris apogees, the perigees of the debris would still be the low point it occurred at and just like Phobos-Grunt not have a long orbital lifetime.
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Offline Vladi

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #804 on: 11/11/2011 07:01 PM »
According to a guy on NK they have the launch window until the 20 November (not considering the possibility that they might expend too much propellant trying to get out of the lower orbit by then).

ESA is using its ground stations and is attempting to send/receive signals according to rumours at least today and tomorrow.

By the way, the lower part of the craft has nothing in common with Fregat as far as control systems and electronics go.

Offline Prober

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #805 on: 11/11/2011 07:03 PM »
I wonder if we could provide some small summary of where we are, as I really need to get a new article on (as opposed to what is the launch day article currently on site). So I'm going to write a shortish state of play summary and give it a bit of a fresh look by adding NASA's interest in Phobos.

I just need to check what we appear to have as facts - and no more, the thread is for NK comments, speculation, etc:

We had nominal Zenit-2 first and second stage performance.
First - and obviously the second - burn on the Fregat-derived stage did not occur, because the flight computer went into safe mode (reason unknown).
Recovery of the computer has been unsuccessful - partly because of antenna issues (I'm not clear on this element) - during all passes thus far.
They do have more than the three days as the solar panels are extended and sun-facing.
However, it is expected to re-enter at the end of the month if this is a Loss of Mission scenario due to decaying orbit.

Much appreciated if anyone can tick some boxes/correct me - I'd be a fool to not ask and end up making a basic mistake in an article.

was under the impression the solar panels would not deploy until the burns were done.  None of the info is "solid"
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I wonder if we could provide some small summary of where we are, as I really need to get a new article on (as opposed to what is the launch day article currently on site). So I'm going to write a shortish state of play summary and give it a bit of a fresh look by adding NASA's interest in Phobos.

I just need to check what we appear to have as facts - and no more, the thread is for NK comments, speculation, etc:

We had nominal Zenit-2 first and second stage performance.
First - and obviously the second - burn on the Fregat-derived stage did not occur, because the flight computer went into safe mode (reason unknown).
Recovery of the computer has been unsuccessful - partly because of antenna issues (I'm not clear on this element) - during all passes thus far.
They do have more than the three days as the solar panels are extended and sun-facing.
However, it is expected to re-enter at the end of the month if this is a Loss of Mission scenario due to decaying orbit.

Much appreciated if anyone can tick some boxes/correct me - I'd be a fool to not ask and end up making a basic mistake in an article.

Chris to play devils advocate here, since there was no telemetry during the critical events do we know that?

Do we know that the first burn not occurring was due to the computer being in safe mode? Is it possible something else caused the burn to abort and that triggered safemode?
Do we know that the solar panels are extended and sun facing? Based on amateur observers we know the vehicle is stable and not tumbling.
Also did you read Ted Molczan's post ( http://satobs.org/seesat/Nov-2011/0116.html ) that oddly the two TLE's may point to a Delta V of ~1.3   while over Baikonur?

Anywho looking forward to the article.

Thanks. Although I can only go on official news for this, as much as I'll be careful not to go making claims of certainty.

Offline iamlucky13

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #807 on: 11/11/2011 07:07 PM »
I wonder if we could provide some small summary of where we are, as I really need to get a new article on (as opposed to what is the launch day article currently on site). So I'm going to write a shortish state of play summary and give it a bit of a fresh look by adding NASA's interest in Phobos.

I just need to check what we appear to have as facts - and no more, the thread is for NK comments, speculation, etc:

We had nominal Zenit-2 first and second stage performance.
First - and obviously the second - burn on the Fregat-derived stage did not occur, because the flight computer went into safe mode (reason unknown).
Recovery of the computer has been unsuccessful - partly because of antenna issues (I'm not clear on this element) - during all passes thus far.
They do have more than the three days as the solar panels are extended and sun-facing.
However, it is expected to re-enter at the end of the month if this is a Loss of Mission scenario due to decaying orbit.

Much appreciated if anyone can tick some boxes/correct me - I'd be a fool to not ask and end up making a basic mistake in an article.

That mostly sounds right to me.

The belief that the solar panels are deployed is based on the reports that they had one successful telemetry pass (downstream only). I think the single telemetry pass is worth mentioning, even if you consider the belief the drop tank is blocking further signals to be speculative.

I don't know if it's certain the spacecraft is in safe mode. Don't most safe mode's involve the spacecraft broadcasting a diagnostic tone?

I've seen quite a few estimates over re-entry timing, ranging from two weeks out to mid-December. Not having dug into it too much, I tend towards believing the later estimates since this is a very dense spacecraft at the moment.

Aside from RussianSpaceWeb, Emily Lakdawalla seems to have done a decent job sorting down all of the current info into a semi-coherent state. A decent chunk of her article is based on the discussion here, so it might save you some digging back through these 50+ pages.

http://planetary.org/blog/article/00003254/

Offline JWag

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #808 on: 11/11/2011 07:12 PM »
With American probes it seems to be common practice to build a flight vehicle and at least one backup vehicle.  The backup vehicle is kept up-to-date and configured identically to the flight vehicle, assisting in troubleshooting and analysis.  Is this a Russian practice as well?


Offline LegendCJS

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #809 on: 11/11/2011 07:16 PM »
Quote from: iamlucky13 link=topic=15610.msg828128#msg828128
my post reflected the extreme end of optimism,....... if they are perhaps able to recover the spacecraft but not in time to reach Mars it wouldn't be possible to even consider other missions.
because your first IF in itself borders on miracle, I separate 'miracle' from optimism, I would never for example say I am optimistic that I could win a lottery ticket where odds are 1:10000000 because IMHO such a statement would sound nonsensical. As to your second assertion spacecrafts are built for a concrete missions, they are highly specialized, and it is mpossible to think how such Phobos- Grunt could be reused in Earth orbit (or any orbit outside of Mars) earthly satellites are considered often a 'total loss' if their orbits are slightly off (insurance covers total amount) and PG would still be a junk even if you managed to turn on it's cameras or instruments, I am running out of breath....

Exploration probes have been known to be re-tasked to do extended mission stuff, think Deep Impact being used to infrared astronomy iirc, and stardust being re-tasked to go look at the deep impact crater a few months later. 

P-G has on-board a number of instruments that can still gain valuable knowledge provided it were close enough to an interesting target, and it has a whole lot of fuel to make that happen.

But even if the Fregat derived propulsion system can never be restarted, a portion of P-G is designed to return to earth and it holds the Planetary Society Phobos LIFE experiment, which while not having exited the van-allen belts or having been in space for the initially planned amount of time, might still be worth recovering in one piece to see how the organisms did.  And if they can get some partial firing of the Fregat stage they can take the LIFE canister on a inner solar system cruse then back to earth for a more "too spec" exposure profile.

Plus don't forget about Yinghuo-1, it was designed to be a free flying satellite.  Perhaps  enough P-G control abilities remain or can be recovered to release Yinghuo-1 for earth observation at the very least.

I think the above is ample background information to make the belief rational that there is a whole spectrum of science possibilities and partial mission successes that are still possible, provided they can finally get talking to the dang thing.  And some of these possibilities might involve just doping the booster tank straight out before using up that fuel- which would open up the communication pathways according to some of the theories presented on this site (assuming they could just get that one command though in the first place.)
« Last Edit: 11/11/2011 07:18 PM by LegendCJS »
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Offline iamlucky13

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #810 on: 11/11/2011 07:30 PM »
Now that the subject of explosions has come up, let me ask this: if F-G remains stuck in its decaying orbit and at least one tank is already venting, what is the likelihood of more leaks leading to a hypergolic mix that triggers a chain reaction of larger and larger explosions?

How much more/less likely is an orbital debris impact that triggers likewise?

If it happens, does the secret US death ray laser get blamed? Or the Chinese one?

If it happens, how energetic could some of the fragments be ejected forward?

That is, could they reach ISS altitude and add to the already pesky Chinese ASAT debris threat?

Is an on-orbit explosion a 'happy ending'


Sorry if I missed anything - is a venting tank speculation or based on a credible rumor?

A major explosion does not seem out of the question, but my gut says the likelihood is low. The reaction would be occurring outside the tanks. This doesn't directly increase pressure inside the tanks, but I suppose it could increase heating such that relief valves couldn't keep up with the pressure rise. Likewise, a relief valve could simply fail to operate and cause an explosion even in the absence of reacting fuel.

Conceivably, an exploding tank could put some degree at ISS altitude, but as kevin-rf pointed out, it would have a low perigee and decay quickly. I don't have numbers to offer.

Based on the PR diagram, I counted 23 visible tanks on this probe of various sizes and contents. One could be sitting in direct sunlight and explode, while others in shadow freeze, survive the explosion, and re-enter.

It will either be the US death ray laser or HAARP.

And on-orbit explosion is a less sad ending than intact re-entry over a populated area, but the only really happy endings involve recovery and useful research being accomplished.

Offline JimO

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #811 on: 11/11/2011 07:33 PM »
Jim O, any potential explosion would be in a low orbit and even though it would be energetic and boost some debris apogees, the perigees of the debris would still be the low point it occurred at and just like Phobos-Grunt not have a long orbital lifetime.

Sure, the pieces would have very short lifetimes. And it's a big sky.

But since we don't know the configuration that the propulsion system was left in by the command failure [i.e., tank pressures, valve configuration, etc], I'd speculate that the odds of cascading prop-related problems is higher than from an inert, safed, or exhausted system.

A lot higher, even if probably not high enough to happen in its remaining lifetime.


Offline kevin-rf

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #812 on: 11/11/2011 07:34 PM »

Sorry if I missed anything - is a venting tank speculation or based on a credible rumor?


Source: http://satobs.org/seesat/Nov-2011/0110.html

"Phobos-Grunt: latest two TLEs suggest manoeuvring or venting"


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Offline hop

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #813 on: 11/11/2011 07:47 PM »
I just need to check what we appear to have as facts - and no more, the thread is for NK comments, speculation, etc:
Relying only on official sources, we have very little...
Quote
We had nominal Zenit-2 first and second stage performance.
First - and obviously the second - burn on the Fregat-derived stage did not occur,
I think we can call this 100% confirmed, since the the spacecraft and Zenit stage were found together in the expected pre-burn parking orbit.
Quote
because the flight computer went into safe mode (reason unknown).
The sequence of events and current state of the spacecraft isn't clear to me. The have been contradictory reports of how much has been received since the confirmation of successful separation. Do we know for sure if there has been any telemetry since then ?
Quote
Recovery of the computer has been unsuccessful - partly because of antenna issues (I'm not clear on this element) - during all passes thus far.
I'm not sure there has been any mention of the "antenna issue" in official sources, but the consensus (based on http://www.russianspaceweb.com/phobos_grunt_launch.html#11_9 which is relying on unofficial sources but likely well informed) appears to be the the spacecraft was never designed to be commanded prior to the first 2 burns, so among other things the drop tank blocks the low gain antennas.
Quote
They do have more than the three days as the solar panels are extended and sun-facing.
Today's (edit: Just realized that was actually not from today, sorry for the confusion) terse and uninformative statement from roscosmos http://www.roscosmos.ru/main.php?id=2&nid=18227 says (machine translation)
Quote
Adjusted analysis of the orbital parameters and energy supply on board showed that these commands must be issued within 2 weeks.
Which suggests that is correct, or at least the official line. In addition, visual observations suggest Phobos-Grunt is not tumbling ( http://www.satobs.org/seesat/Nov-2011/0111.html http://www.satobs.org/seesat/Nov-2011/0115.html ) , which supports the idea that it could still be maintaining active control.
Quote
However, it is expected to re-enter at the end of the month if this is a Loss of Mission scenario due to decaying orbit.
I've seen estimates from the end of this month to the end of next month. As we know, these things are uncertain and depend on the configuration of the spacecraft and variability in the atmosphere. Presumably LOM would occur before that, since they wouldn't be able to reach Mars. AFAIK the original launch window only extended to Nov 25th, even before you count the cost of drag, orbital precession etc.
« Last Edit: 11/11/2011 09:05 PM by hop »

Offline input~2

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #814 on: 11/11/2011 07:57 PM »

However, it is expected to re-enter at the end of the month ...

Edit: According to the last 2 elsets (sharply decreasing decay parameter measured in rev/day²), re-entry date has been pushed forward back, ie it will occur later(using SatEvo)
« Last Edit: 11/11/2011 08:49 PM by input~2 »

Offline iamlucky13

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #815 on: 11/11/2011 08:06 PM »
Quote from: iamlucky13 link=topic=15610.msg828128#msg828128
my post reflected the extreme end of optimism,....... if they are perhaps able to recover the spacecraft but not in time to reach Mars it wouldn't be possible to even consider other missions.
because your first IF in itself borders on miracle, I separate 'miracle' from optimism, I would never for example say I am optimistic that I could win a lottery ticket where odds are 1:10000000 because IMHO such a statement would sound nonsensical. As to your second assertion spacecrafts are built for a concrete missions, they are highly specialized, and it is mpossible to think how such Phobos- Grunt could be reused in Earth orbit (or any orbit outside of Mars) earthly satellites are considered often a 'total loss' if their orbits are slightly off (insurance covers total amount) and PG would still be a junk even if you managed to turn on it's cameras or instruments, I am running out of breath....

I repeat, look at the history of the Hayabusa mission before you call recovery dependent on a miracle. Mission control losing contact for several days during a critical time period was one of the least remarkable of the things that went wrong during this successful mission.

http://planetary.org/blog/article/00002530/

And if you have a satellite intended for a geostationary orbit that ends up high, low, or at a non-zero inclination and unable to move to the proper orbit, it is probably useless. Ground equipment designed to send/receive to a fixed point in space generally can't track wandering spacecraft. You're comparing repurposing a spacecraft that can't even move to one that, for purposes of a hypothetical recovery, can.

There are many NEO's that take much less delta-V to reach than Phobos. It has the basic capability to approach such an object and land.

I'm less clear if sample return is possible. The low downforce on Phobos against which to react digging loads due to a gravity of less than 0.01% that of earth's was already a concern. There was discussion about techniques like using screw anchors or downfiring thrusters during digging, but I've not seen authoritative confirmation any such technique was implemented. A smaller NEO could make digging even more difficult.

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Thanks guys. What a mess this all is! I miss the days of shuttle, because if one of the orbiter's sneezed, you'd have 15 PRCB presentations and by the second IPR coverage to play with :)

Offline Blackstar

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #817 on: 11/11/2011 08:12 PM »
There are many NEO's that take much less delta-V to reach than Phobos. It has the basic capability to approach such an object and land.

Forget about it. There are very few windows for NEOs even at low delta-v.

That's one of the dirty little secrets in all the talk about human missions to NEOs. Right now the target set is bad. Really small. Gotta do a better survey and find more targets.

Offline Blackstar

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #818 on: 11/11/2011 08:14 PM »
With American probes it seems to be common practice to build a flight vehicle and at least one backup vehicle.  The backup vehicle is kept up-to-date and configured identically to the flight vehicle, assisting in troubleshooting and analysis.  Is this a Russian practice as well?

No, it's not common practice for American missions. There are often flight instrument spares, but there's no backup vehicles. That practice was abandoned in the 1970s. No backup for Cassini, Galileo, Magellan, the MERs, Curiosity, CONTOUR, New Horizons, MRO...
« Last Edit: 11/11/2011 08:14 PM by Blackstar »

Offline jimvela

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #819 on: 11/11/2011 08:16 PM »
With American probes it seems to be common practice to build a flight vehicle and at least one backup vehicle.  The backup vehicle is kept up-to-date and configured identically to the flight vehicle, assisting in troubleshooting and analysis.  Is this a Russian practice as well?

While it is still common practice to build engineering models of subsystems (for example, an EM avionics box might be integrated into a software test bed), it is NOT a common US practice to build a backup vehicle any longer.

There are exceptions (Two MER, for example)


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