Unless Global Surveyor's done a lot of attitude gas jetting, it's on-orbit location should be pretty well known. I don't, however, have a clear idea of how the along-orbit uncertainty spreads with time. What's not known at all and is the object of investigation is MGS's ATTITUDE.

Of course, if they spot a Klingon bird of Prey next to it.......

Now if we could just get something other than random noise (and fullsome self-praise) from the remote-viewing pseudo-psychics....(sigh)

The along-track uncertainty is likely the principal uncertainty here. The exact orbit need only be slightly higher/lower for significant timing differences to be accumulated on a time scale of days. These would manifest as a change in when the spacecraft passes a certain point in its orbit, with respect to the (practically identical) reference orbit. Given the speed these things move, even a couple of seconds worth of timing error means they move quite far along track. As to how much of a contributor the possible thruster firings are (ideally, they should not be one at all) or how significant the atmospheric friction is in lowering the orbit is open to question.

Assuming no net thruster firings, it's a relatively simple <and probably documented somewhere in published mission navigation papers, like AAS Advances in Navigation, or AAS Advances in Communication and Control type volumes in engineering libraries>, how the along track knowledge degrades with time following a normal orbit solution.

When I started this place a couple of years back - I never thought I'd see a debate between MOC/CTX and HiRISE people over the relative difficulty of photographing spacecraft - what a very very sureal thing to read over ones cornflakes

Doug

A very back-of-the envelope calculation, could be very wrong, but still I think it's illustrative:
Assuming a 118 minute orbit, 3800 km orbital radius, 3.37 km/s orbital velocity here. That amounts to 122 orbits in 10 days. Let's suppose we change the orbital radius by just 100 meters, from 3800 km to 3800.1. Given the ratio of orbital periods T1/T2=SQRT(R1^3/R2^3), that gives me around 0.9999605 T ratio. Multiply (1- 0.9999605) by 118 minutes, that amounts to a difference of about 0.28 seconds per orbit.
Now, 122 * 0.28 s * 3.37 km/s = 115 kilometers in along-track drift. Not exactly peanuts. It's not getting any smaller as time passes, either. Note how even a small, 100 meter radial change in orbit radius results in an 3 orders of magnitude larger change in along-track position.

To change the subject just a bit, if MGS were not able to orient its solar panels toward the Sun, wouldn't that mean that it couldn't recharge its batteries, which would leave the spacecraft electrically dead (i.e., totally dead)? In fact, isn't that what killed the Phobos-1 spacecraft (though a different root cause of losing solar panel orientation)?

This is a worst case scenario, I know, but we seem to be running out of other scenarios.

Yup - what you describe is the process of remaining power positive.

The moment you have less power than you require for basic survival....then you are running a very dangerous game. I imagine a Mars orbiter would get very cold very quickly without power whilst in eclipse - Once you have a spacecraft that has basically 'browned out' - you have no means to maintain attitude, and nasty things can start to happen such as frozen prop etc.

The only story I know of a recovery from that sort of problem was with SOHO - and that was a very very lenghty procedure that began with something as crazy as bouncing radar signals off the spacecraft with the Areciebo dish to identify its orientation and spin rate.

In some respects - imaging MGS with an one or more MRO instruments is a martian equiv of that - identify the physical config of the spacecraft - or even better - do it twice to identify what, if any, attitude control it is exhibiting.

Doug

I am hoping HiRISE will succeed and MGS will live to return the favor....
(I have to admit when I first typed the above, I used the conditional "would have." I think my faith is beginning to shake.)

122*0,28 = 34 seconds. So what you do is start taking pictures say 30 seconds before the nominal expected arrival time at the aimpoint and keep it up for one minute. The interval depends on the cycle time of the camera and the FOV since the interval must be shorter than the time MGS will need to cross the FOV. MGS should show up in at least one image and once you have pinned down the current orbit it should be possible to find it again at higher magnification.

tty

All the camears in question are push broom cameras - they require the motion of the planet below them to build up the 'length' of an image.

You can get creative with their operation when it comes to tracking down MGS though

Doug

MRO has been been commanded...

2006-319T18:20:35 ri3500 r01st_mgs_image_319.abs

Sent about 6 hrs ago. Can't tell which instrument it is ( although CTX as 'pin down' and HiRISE as a follow up would make the most sense )

Meanwhile, many repeated commands to MGS - Tuesady and most of Wednesday seemed packed full of more explicit transmitter commands - turning on heaters etc etc - but repeated many times - cycling between 'sides' so one presumes still an 'in the dark' set of commands...just trying all options.


Doug

According to MGS Project Manager Tom Thorpe, they're actually using the navigation camera. I got a lot of info from him this afternoon.

Mars Global Surveyor Falls Silent: All Other NASA Spacecraft at Mars to Assist Recovery Efforts

--Emily

That's the same info I've gotten, so it would at least seem to be consistent. Good work on the article! It sure will be interesting, but I do believe the star camera really is the best instrument to try and find MGS, with HiRISE taking a picture shortly thereafter. Not sure when it will happen, that all depends on the results with the star camera, but it does seem to be the most accurate for the moment, and I only say that because no one is really certain what will happen.

Just a mild suggestion to the moderators -- perhaps the subtitle of this thread is, um, inappropriate? At least until we know whether or not we'll get MGS back, it seems mighty incorrect to be discussing these rescue efforts in a thread subtitled "still going strong"...

-the other Doug

Indeed. Done.

I was considering changing the title anyway considering we don't actually know what 'mode' MGS may be in by now. I hadn't noticed the subtitle, good call oDoug.

(To the tune of Pink Floyd's "Comfortably Numb")

Hello.
Is there anybody out there?
Just bleep if you can hear us.
Is there anyone home?

Come on now, MGS.
We're worried by your silence.
Maybe we can ease your pain,
Get you taking pics again.

Relax.
We're trying hard to find you.
You've been quiet for a week now:
Can you tell us where it hurts?

There is no pain, you are receding.
A distant blue star on my horizon.
You are only coming through in waves.
Your lips move but I cant hear what youre sayin.
When I first arrived I had a fever.
My gyros felt just like balloons.
Now I got that feeling once again.
I cant explain, you would not understand.
This is not how I am.
I have become comfortably numb...

Thanks for the heads up Emily - nice write up....I had forgotten about the old Nav camera...we never saw much from that (well, one image) - I hope they dump it's entire results onto the PDS...might make a nice movie

Doug

The solar panel trouble indications that marked the last communications with MGS - were they traceable to the same joint that was stressed during aerobraking many years ago? My brief keyword search did not turn up any mention of a connection but it seems like this should be in the minds of the diagnosticians as they try to figure out what went wrong. Perhaps at this stage it would not actually make the problem any easier to solve though.
Peter

They're using the Optical Navigation Camera ("star camera" usually refers to the wide field of view Galileo Avionica attitude control star cameras.) ONC has some advantages relative to CTX for this: it's mounted on the -Z side of the spacecraft so the spacecraft doesn't have to slew as much to point at MGS; it's a framing system it may be easier to compute geometry; and it can expose a frame for many seconds (which can either help or hurt.) On the other hand, it has a narrower field of view than CTX, its extra sensitivity doesn't help much since MGS is pretty bright (perhaps seeing the star background will help, but I don't think it's mandatory), and I'm not sure how rapidly it can take back-to-back frames. CTX can easily image for several minutes and cover a patch of sky ~6 degrees wide and maybe 20-30 degrees wide.

Hehe. I almost fell off my chair, laughing at that, but how true. I've learned so much about spacecraft operations simply by reading the recent comments here.

Emily: That was quite an excellent summary. It clarified several things that I wasn't sure of. I've worked through some relatively complicated "fault tree analyses" of equipment failures on earth, but this one is beginning to look like the proverbial "tough nut to crack."

I don't want to see this important spacecraft lost. I can only keep my fingers crossed for those of you who are working on this problem. All I can say, fwiw, is "Good luck."

Doug's quote would make an excellent subtitle for UMSF.com!

Seriously, best wishes for MGS; she will someday be greatly missed, but please not yet. I remember the excitement way back when of finally being able to really see Mars again after so many, many years...in fact, to see the latest & greatest daily via the then-newfangled Internet. My ex eventually became quite annoyed with my constant calls of "Honey, come here, you gotta see this!!!" as the spectacular images just kept on coming...

First one was Wednesdayat 1820 UT....that I would assume to be the ONC sequence

The last four were all about 20 hours ago, early Friday morning - and include what I woudl guess to be two pointing commands, the imaging command, and one other that I don't really 'get' ( the eph_ one )

What is a bit odd is that the 321 imaging command is basically the same as the 319 one....it may be that it's just that - the command is the same...or it may be that they need another hack at taking the image with the ONC first.

Doug

Just speculation, but I always thought that "eph_mars" in a command was an ephemeris update to give
the best possible coordinate data to the spacecraft.

Well - I thought that, but why would the spacecraft need ephemeris for itself or another spacecraft? That's what WE need so we can tell it what to do and when - unless it's a far more intelligent spacecraft than I thought and they're just telling it the orbital params of MGS and letting it work everything out itself.. (which I really really doubt)

Doug

MRO is quite a smart spacecraft actually, it's the first one to target the location and not the time. But my guess would be that MRO took two pictures to blink them and see if anything moves (I'm assuming the command log was from MRO). This is just my guess, no inside info.

Hello.

This is my first post in the forum. I'm Svetlio from Bulgaria.

Today MRO should take pictures of MGS - any news? We know that today MRO will use its navigation camera,and if MGS is detected, MRO will make another set of picture with its HiRISE camera to see the orientation of its solar panels.

I assume everybody's so quiet because nobody knows anything yet.

We're just waiting for some word from the folks who do know (who are understandably a bit busy right now and have a lot on their minds besides this board).

I imagine that when there is news, this'll be one of the first places it appears.

Welcome, Svetlio, nice to have you onboard the good ship UMSF

These are earlier today - 0013 - 0016 UT Monday, and the first imho, is a HiRISE imaging command - the last two the pointing commands.

Doug

Think we're going to see any of these MGS images? I'm a little surprised that were now 2 weeks into the science mission and we haven't seen anything at all yet.

I know what you mean. No new Oppy Pancams since the 10th, no new MGS pics... I fear a crack team from ESA has taken over Mars Operations and is forcing them to work to their image release rules, i.e release b****r all...

You mean HiRISE images.

I would have thought the efforts would have been going into finishing up the viewing software that has been mentioned elsewhere instead of doing the rush-job on releasing images that we saw during the transition phase. However - the MGS imaging efforts have probably disruted things at HiRISE HQ, and indeed to some extent the command and reception of MRO data in general via DSN congestion.

Give them month or two to get into the flow of the primary science phase, get the viewing software sorted..THEN - you will have more images that time.

It takes 6 to 12 months for an MGS MOC image to be released (if the PDS release is done on time) .... to start moaning about HiRISE releases at this time would be a long long way from reasonable ( not to mention off topic for this thread)

Doug

Yes, but we haven't seen anything new in nearly 5 weeks. Which seems to contradict what was being said at the press conferences.

But nothing. Want to have this debate, have it in another thread...

With respect to HiRISE images, well, there should be a nice batch released sometime soon, it should be this week... As for the why, well, just see the HiBlog. I think it's actually harder to release orbiter pictures, due to needing the SPICE kernels, which are only released once a week. After that, we just had to sit back and wait. But, hopefully that time is over now, so we should be releasing pictures soon.

As to why nothing about MGS has been released, well, my guess would be because there's nothing to release. The process isn't an easy one, and MRO/NASA will want to make sure they get it as exactly right as possible, thus it might take some time. Remember Victoria Crater, it was released only a few days after the image was taken, and I would well imagine the same type of thing will occur with MGS. As to when that will occur, well, my guess would be ASAP. Note however that nothing here is based on inside info, this is purely coming from my brain/public sources.

I find it hard to gripe too much. The firehose is about to open! We'll have way more than we can handle once MRO settles in and as Mars works toward opposition. The lull in the action is kind of nice actually. And if HiRise snaps a pic of MGS, wouldn't that be something for the ages? So it's all good far as I can tell 'cept for poor old Global Surveyor. MGS phone home please.

Nov. 20, 2006

Erica Hupp/Dwayne Brown
Headquarters, Washington
202-358-1237/1726

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278

MEDIA ADVISORY: M06-179

NASA PROVIDES MARS GLOBAL SURVEYOR UPDATE

NASA will hold a media teleconference at 1 p.m. EST, Tuesday, Nov. 21,
to discuss the status and science accomplishments of the Mars Global
Surveyor. The 10-year old spacecraft is the oldest of five NASA
spacecraft currently active at the red planet.

Reporters must call the NASA Jet Propulsion Laboratory, Pasadena,
Calif., media relations office at 818-354-5011 for participation
information. Images supporting the briefing will be posted online at
the start of the briefing at:

http://www.nasa.gov/mission_pages/mgs/20061121.html

Briefing participants:
--Michael Meyer, Lead Scientist, Mars Explorations Program, NASA
Headquarters
--Fuk Li, Mars Program Manager, Jet Propulsion Laboratory (JPL),
Pasadena, Calif.

Supporting participants:
--Tom Thorpe, Project Manager, Mars Global Surveyor, JPL, Pasadena,
Calif.
-- Phil Christensen, Principal Investigator, Thermal Emission
Spectrometer, Arizona State Univ, Tempe
-- Michael Malin, Principal Investigator, Mars Orbiter Camera, Malin
Space Science Systems, San Diego

Audio of the event will be available on the Internet at:

http://www.nasa.gov/newsaudio

"NASA will hold a media teleconference at 1 p.m. EST, Tuesday, Nov. 21,
to discuss the status and science accomplishments of the Mars Global
Surveyor."

That has a bad ring to it...sounds funerary.

Thanks for the info! I wonder if "to discuss the status and science accomplishments..." is a sign that this update will sound more like an obiturary?

So much for taking time off for Thanksgiving Why do spacecraft events always seem to happen around major holidays? "Science accomplishments" does sound a bit obituary-like. I'll have to watch & report.

--Emily

No Alfred McEwen would be suggestive that there's no HiRISE image to be unveiled - but they might still have something.

I have to go to a distant relatives funeral tomorrow...then come home and listen to this....I think I'll leave the suit on just in case.

Doug

Well, it does say "The 10-year old spacecraft is the oldest of five NASA spacecraft currently active at the red planet. "
But maybe that's reading too much in it from my end.

Simple, we are still sending it commands, thus it is considered active.

It is indeed! Can't wait! I do wish people wouldn't mistake expressions of frustration and good-natured impatience for "griping" tho No-one's throwing any toys out of their prams because of a lack of images, it's just - well, like I say, frustration. Every image from Mars, whichever probe it comes from, is a blessing, and worth drooling over. So we miss them when they temporarily dry up; only natural I'd say. I know, we've gotten spoiled.

Really hope MGS is found and recovered (its death notices may already have been read out by now, I haven't caught up yet; just back in from work), it deserves better than to just fall silent without telling us why.

I remember the MER images of stars and martian moons from the surface, would enough of MGS show on such am image to better navigate the images from MRO ?

I think the biggest problem with that would be MGS's orbit. It is a high-inclination orbit that passes the equator at 2 pm and 2 am local time. So it either passes over either MER during the day, or too early for it to catch sunlight to make it visible at night.

Apparently the wide angle shots showed something.

http://www.rockymountainnews.com/drmn/loca...5158669,00.html

Keeping my fingers crossed.

This brief video file description suggests MGS is dead. ...item #1...

ftp://ftp.hq.nasa.gov/pub/pao/tv-advisory/nasa-tv.txt

-Dr. Michael Meyer
"We may have lost a dear old friend and teacher."
blah blah - what the instruments have done - blah blah...

Fuk LI
Activities in last two weeks.

On Noc 2nd 3.35 pm Pacific - telem showed more than 50 difficulties to move an array, automatically tried to switch to redundent systems at that time - 5.27pm should have come back, but no communication. In last two weeks - no communication with the spacecraft in a normal fashion. Only time we thought we might have heard from it - late 5th - early 6th - 4 partial orbits showing potential carrier only signal. After that - not heard a thing. Sent 800 command files - none of that has been succesfull.

Tried to use MRO - not easy - our knowledge of MGS location is not good. Do not know exact orientation so don't know how bright it will be. MRO just starting primary science phase and wanted to do everything to make sure we don't impose undue risk on MRO. Last friday used Star Camera. yesterday HiRISE and CTX to image a region where we thing MGS could be. Preliminary analysis has not yielded ANY sighting of the spacecraft. Today and tomorrow - send messages to MGS to turn on its UHF - have Opportunity listen and relay any info via Odyssey.

Not exhausted everything yet...."we believe the prospect of recover is not looking very good at all"

Still ongoing - but that's the 'meat' of it.

Doug

Is the briefing over?

EDIT....OK I found it now