Author Topic: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011  (Read 426868 times)

Offline hop

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #680 on: 11/10/2011 10:57 PM »
So are we all on side with the reports that we'll know one way or the other over the next few hours?
Know is a bit too strong a term IMO. Real certainty will be when they gain control, stop trying or decay/orbital mechanics dictate that it can't reach Mars. But certainly every pass where they can't establish control lowers the chance of a happy outcome :(

Offline Nickolai

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #681 on: 11/10/2011 11:23 PM »
I was looking at Roscosmos's site to see if they had any more info - they've all but removed the words Phobos-Grunt from the main page. But there is a link to a description of the project, which contains a detailed schematic showing antenna positions http://roscosmos.ru/main.php?id=375 (scroll down a bit for the images) Antenna in Russian is Антенна, so look for that.

There's one antenna which is right at the bottom on the lander. It's completely unclear to me whether or not that's the antenna needed to receive the command to activate the transmitter, but it does look like it would be hidden by a fuel tank. Maybe... Perhaps the antenna in question isn't even on the lander but elsewhere in the system.

Online Blackstar

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #682 on: 11/10/2011 11:23 PM »
I know someone doing radar studies of Europa with the Goldstone 70-m. So yes, lots of power.

Slightly off-thread, but do you have a reference/URL for that?  I like to keep up with long-range radar capabilites.

There was a presentation on this at the OPAG meeting in spring 2011. I cannot find that meeting listed on their website, however. But there is somebody bouncing radar off of Europa looking for evidence of a wobble that is caused by the subsurface ocean.

Offline joek

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #683 on: 11/10/2011 11:29 PM »
So are we all on side with the reports that we'll know one way or the other over the next few hours?
Know is a bit too strong a term IMO. Real certainty will be when they gain control, stop trying or decay/orbital mechanics dictate that it can't reach Mars. But certainly every pass where they can't establish control lowers the chance of a happy outcome :(

Concur, but... let us all remember that there's a team out there and this is their baby.  Many (if not all) of them have poured incalculable blood, sweat and tears into bringing it to life.  Baby is hurt.  Baby needs help.  They're trying.  I expect they won't give up and be working 24x7 until it's stone-cold dead-and-buried.



p.s. Excuse me for excessive anthromorphizing, but been there, done that, and the pain is palpable for those who have invested so much time and energy; seeing some people try to put years of effort into the grave prematurely is... annoying.  Let the team do their job.  They'll tell us when and if the mission is dead.  Until then, best wishes and keep the updates coming.

Offline iamlucky13

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #684 on: 11/11/2011 12:13 AM »
I wanted to offer anther quick thanks for all the diligent coverage, especially from the Russian-speaking members who have been relaying word from knowledgeable sources.

Regarding radio power - the LGA's are theoretically obstructed behind tanks, not enclosed in Faraday cages. It seems to me more power presents the possibility of a weak reflected signal reaching an antenna.

Also, I didn't understand the earlier discussion, so clarification would be appreciated if anybody knows:

Are there just 2 LGA's, or more? It sounded to me like there were two LGA's on the sides of spacecraft, and two more on the cruise stage, and the latter would be the antennae being blocked.

If there's more than two, are they all linked to spacecraft, or is one set for the Fregat stage only?

Offline Ronsmytheiii

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #685 on: 11/11/2011 12:23 AM »
Quote
U.S. Strategic Command predicts Phobos-Grunt reentry around November 26. Longshot recover attempts continue

https://twitter.com/#!/tedstryk
« Last Edit: 11/11/2011 12:23 AM by Ronsmytheiii »
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Offline Nickolai

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #686 on: 11/11/2011 12:35 AM »
I wanted to offer anther quick thanks for all the diligent coverage, especially from the Russian-speaking members who have been relaying word from knowledgeable sources.

Regarding radio power - the LGA's are theoretically obstructed behind tanks, not enclosed in Faraday cages. It seems to me more power presents the possibility of a weak reflected signal reaching an antenna.

Also, I didn't understand the earlier discussion, so clarification would be appreciated if anybody knows:

Are there just 2 LGA's, or more? It sounded to me like there were two LGA's on the sides of spacecraft, and two more on the cruise stage, and the latter would be the antennae being blocked.

If there's more than two, are they all linked to spacecraft, or is one set for the Fregat stage only?

From the Russian sources I'm gathering there are 2 high gain transmitter antennas on the sides of the spacecraft (those must be the ones through which they got the initial telemetry after SC separation from the LV) and 2 low gain receivers behind the prop tanks.

Offline SaveMannedSpace

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #687 on: 11/11/2011 12:37 AM »
What stuns me is the only uplink is still in Russia two days later; limiting attempts to issue commands to P-G to once per orbit. NASA offered help but got no interest. ESA is volunteering to pass on any data they might receive from P-G, but to take advantage of all opportunities to save their mission, Russia should let NASA send commands when it is out of range of the Russian dish. Roscosmos: We will be happy to help save the mission; please don't let national pride blind you from asking for help.
Here's a good article--which includes a NASA quote about offering assistance: http://planetary.org/blog/article/00003254/
« Last Edit: 11/11/2011 06:14 AM by SaveMannedSpace »
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Offline hop

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #688 on: 11/11/2011 01:04 AM »
NASA offered help but got no interest.
Do you have source for this ? NASA confirmed that they offered, but I don't see any confirmation of the "no interest" part. It may be that there are practical obstacles to doing anything useful.
Quote
Russia should let NASA and ESA send commands when it is out of range of the Russian dish.
I suspect (just personal opinion, no inside information) the reality is a lot more complicated than that. They have limited resources and are working against a clock. Getting some outside party to usefully transmit commands would likely take resources away from that effort. Keep in mind that some sources have reported that only Baikonur can uplink, even though they have other ground stations that can listen.

It would have been much better to set up contingency arrangements with other agencies would have been before the launch (to some extent they had with ESA), but until there is an actual emergency, politics and NIH play a bigger role.

If the report of the drop tank blocking the low gain antennas is accurate, it appears that a failure before the first burn wasn't something that got a lot of attention, or wasn't expected to be survivable. OTOH, they did request visual observers watch the burn, so obviously some people were concerned.

Offline iamlucky13

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #689 on: 11/11/2011 01:11 AM »
I'd say be careful about assuming it's national pride. If they've never tested relaying commands through US or European assets, they may be hesitant to do so for technical reasons.

Also, it's not clear to me whether either the ESA or NASA has offered to transmit or merely to relay telemetry. Confirmation from anyone in the know would be great.

Offline Skylab

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #690 on: 11/11/2011 01:27 AM »
[snip]
Are there just 2 LGA's, or more? It sounded to me like there were two LGA's on the sides of spacecraft, and two more on the cruise stage, and the latter would be the antennae being blocked.

If there's more than two, are they all linked to spacecraft, or is one set for the Fregat stage only?
I'm going out on a limb here, and would appreciate confirmation. These last few days have been hectic, but I remember reading about 11 antennae total. Of course, some of those would have been on the Chinese probe and the return vehicle. I have no clue if those, if they exist, would be useful for sending any commands at this stage.

As I can't provide the source, please consider this (educated?) speculation.

Offline iamlucky13

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #691 on: 11/11/2011 01:42 AM »
The authoritative data on spacecraft propellant is from anatoly Zak
at http://www.russianspaceweb.com/phobos_grunt_design.html

and he lists 10,100 kg of prop in the main propulsion unit.

Using the ox/fuel mass ratio of the STS OMS, 1.65 to 1,
I calculate
N2O4     6290  kg [using proper rounding accuracy & significant digits]
Heptyl   3810   kg

The cruise stage carries an additional 1050 kg total prop. The return stage design had 40kg of prop several years ago but has doubled in mass since then, so perhaps it has 80 kg now.

Grand total, about 11160 kg, eleven metric tons of nastiness.

The N2O4 freezes at -11C, which could happen, but the heptyl freezing point looks way, WAY too cold for it to freeze. 


I want to bring this up again, because you're being widely quoted by other journalists about the potential hazard.

This isn't intended as a criticism, because your quotes seem to be reasonably general and have no control over how others excerpt your original statements, but I know from several discussions lots of readers are assuming this is exactly like USA-193. I don't think we can reasonably know yet what will happen to this fuel in 2-3 weeks. USA-193's fuel had 14 months to freeze.

Furthermore, we don't really know what the net heat transfer is in this case. As I'm sure you know, it depends on the insulation of the tanks, the reflectivity of their coatings, the spacecraft orientation, and whether any thermal control systems for the fuel either on the spacecraft or the Fregat stage is functioning. I wouldn't expect thermal control in the drop tank, so perhaps it is the biggest concern, but the tanks used for the Mars orbit insertion, lander, and return vehicle obviously need some way of ensuring the fuel remains liquid...passive design at a minimum.

Keep up the good work.
« Last Edit: 11/11/2011 01:51 AM by iamlucky13 »

Offline HIPAR

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #692 on: 11/11/2011 01:46 AM »
Concerning all this talk about sending commands from the ISS, Goldstone and ESA, do any of these facilities actually have a capability to transmit in the 7 Gigahertz (not 7 MHz) spectrum?

Is there some international agreement to standardize telecommand operations to those frequencies with common modulation and message protocols?

---  CHAS
« Last Edit: 11/11/2011 01:48 AM by HIPAR »

Offline iamlucky13

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #693 on: 11/11/2011 02:00 AM »
Concerning all this talk about sending commands from the ISS, Goldstone and ESA, do any of these facilities actually have a capability to transmit in the 7 Gigahertz (not 7 MHz) spectrum?

Is there some international agreement to standardize telecommand operations to those frequencies with common modulation and message protocols?

---  CHAS

7 GHz is in the X-band, which is one of several used for satellite communications (and radar, and other purposes). DSN does indeed support X-band.

There are international agreements about the use of these frequencies, but I have no idea about standardizing data formats and commands.

Offline JimO

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #694 on: 11/11/2011 02:19 AM »
I want to bring this up again, because you're being widely quoted by other journalists about the potential hazard.... I know from several discussions lots of readers are assuming this is exactly like USA-193. I don't think we can reasonably know yet what will happen to this fuel in 2-3 weeks. USA-193's fuel had 14 months to freeze.

Furthermore, we don't really know what the net heat transfer is in this case. As I'm sure you know, it depends on the insulation of the tanks, the reflectivity of their coatings, the spacecraft orientation, and whether any thermal control systems for the fuel either on the spacecraft or the Fregat stage is functioning. I wouldn't expect thermal control in the drop tank, so perhaps it is the biggest concern, but the tanks used for the Mars orbit insertion, lander, and return vehicle obviously need some way of ensuring the fuel remains liquid...passive design at a minimum.

By all means we need to keep revisiting this, it often seems more magic than 'rocket science'. The degree of chilling is a function of all these things and more, and exactly as you said, the amount of time available, especially in this case, is very important.

Spherical tanks tend to survive entry robustly for several reasons, including fast decel when empty, and high heat-rejection capability when venting heated contents [especially boiled contents, where the thermal input has to purchase the 'heat of vaporization' as well as simple mass warming] while inducing rotational torques on the tank that distribute external heating and help mix contents.

Freezing is just another way to elevate -- WAY elevate -- the heat-sink ability of the internal mass. It's not just a matter of calories per gram per degree now, it also includes the VERY significant plateau at the 'heat of fusion' threshhold, where major heating can't raise the average temperature while the solid is converting back to liquid.

Recall the freeze-up of Salyut-7 in early 1985. All the water froze solid, but I never could find any data on the prop tanks. Can any Russian colleagues help us?

PS, I have no problems with criticism. 8-)
« Last Edit: 11/11/2011 02:21 AM by JimO »


Online Chris Bergin

NASA offered help but got no interest.
Do you have source for this ? NASA confirmed that they offered, but I don't see any confirmation of the "no interest" part. It may be that there are practical obstacles to doing anything useful.

I was having a chat with a couple of NASA people (note, I mainly know HSF people) about something else, but brought this up. I'm told that is an unrealistic assumption (the "no interest"). Also was told this is now looking like a lost cause, but we were getting to that stage already.

Still hoping for a late success. Imagine how much of a boost it'll be if they find a way to turn this around! Also refer to CBased's comment, about how everyone's pulling for the same result - which is a nice constant with space flight.

Offline spectre9

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #697 on: 11/11/2011 03:22 AM »
Looks like this is over now.

Thanks for all the updates.

 :(

Offline Nickolai

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #698 on: 11/11/2011 03:34 AM »
Also was told this is now looking like a lost cause, but we were getting to that stage already.

Yea, I was thinking, even if they somehow manage to magically bounce the signal off something weird and get it through to get the SC to talk, then what? There's no way they'll be able to upload an entire command sequence (or at least I imagine any command to have the spacecraft do something with its engines is going to be longer and more complicated than switching the radio on.

Offline Nickolai

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #699 on: 11/11/2011 03:35 AM »
Looks like this is over now.

Thanks for all the updates.

 :(

A bit premature don't you think? The SC is still up there, they're still trying.

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