nasa press brief

I need to come up with some snappier titles for these postings ;) The NASA/JPL press briefing, broadcast on NASA TV, will begin in about 15 minutes (9 am PST) and I'll post notes when it's completed. In the mean time, you can check out a couple of good Mars Exploration Rover-related program activity sites that I've recently found to be useful, Universe Today, and Spirit Imagery.

Not a morning of good news :(

updated with more info after I replayed the brief. (on replay I realized that I probably miss about 20% of the information. I suppose 80% is better than none :-) Pay particular attention to the last couple of paragraphs where Pete says we've probably got a signal that would indicate that important systems, like power, are at least somewhat functional. That, if confirmed, is very, very good news.

Pete Theisinger: At yesterday's press conference we reported what we thought was weather related communications problems at Canberra. We now know we have had a very serious anomaly on the vehicle. And we're very limited in our ability to learn what's going on because we're not receiving telemetry for the last 12 hours or so. Yesterday afternoon 1 o'clock on Mars we sent a sequence and we received a beep in response indicating that it received the command and that it was activating that sequence. We had an afternoon 2pm HGA pass that did not occur. Then, later we had no response via Odyssey in the 4PM or 4:30 pass. No indication from Odyssey that it received UHF from Spirit. At 1:30, 2 am we had MGS pass. It was anomalous. MGS believes it saw UHF transmission but there was no data in the packets and the period was very short, only got 2.5 minutes of anomalous data (of a 14 minute pass). 4 am Odyssey pass received no data and we didn't receive data from this morning's normal DTE comm. We also didn't receive the fault state communication at 11 am. That's where the spacecraft has entered fault mode and knows that and knows to communicate with us at a different time. We don't have any one scenario that could explain all of these anomalies. We've been working on fault scenarios, developing todo lists, we've run yesterdays sequences through the testbed with no anomalous results and that's our current state of knowledge. Where we are right now: The rover is getting towards the end of it's day. Team has been up for a very long time. We're going to send them home for some sleep. We're going to pick up activities in the early evening. We'll be looking for the MGS and Odyssey passes this evening. And we'll decided what our go forward plan is based on a plan developed later tonight. As you know, we do have another spacecraft coming in. 2 days out from Opportunity EDL. Not going to do TCM5. Navigation was good for that and this event definitely took that off the table. We are prepared to do a TCM6 on Saturday if it's called for but navigation should be good and we probably won't need to do that. We do not have any staffing conflicts. There are some person ell issues that may arise in the next 48 hours and part of the planning tonight will be to decide how to prioritized those. That's all I have of a general nature and I'll take questions.

Q. Have you lost contact with spirit? If so was the last you heard this beep you got yesterday morning?

Richard Cook: There were beeps that we heard yesterday afternoon on Mars, yesterday morning here. Then we got the MGS signal indicating that it heard through the UHF link in the middle of the night, Mars time, about 8:30 PM our time, that was a little bit not what we expected during that MGS pass. We saw a signal indicating that the rover's radio was on but there wasn't data present. The rover wasn't sending data, only sending zeros and ones, it was sending a random pattern of zeros and ones. We understand very well why that would occur. What it means is that the radio was on but the computer wasn't sending data over to it. Radio just sends out this pseudo-noise. We did at least see a signal.

Q. You have multiple tones and each tone tells you something specific. What did this one tell you.

Richard: The tones are just one kind, a 5 minute long carrier only session telling us "hey, I got the command. I heard you, and here's confirmation that I heard you." We got 2 of those yesterday afternoon. We're attempting to do some more of those today to see if we can get the vehicle to respond. We're not yet done with that. It's not Earthset at Mars landing site so we're trying to do that.

Q. What needs to be working in order for it to send those tones.

Richard: Quite a bit. The whole avionics, the computer has to work, ability to talk to radio, radio has to work, radio itself and the amplifier in the antenna and all the switches between those. A number of things in a chain has to work. We don't know what is the state of the software relative to sending out these beeps. One thing we learned from Pathfinder is that it we want the spacecraft to try to communicate with us whenever it can. To do that we've implemented in software some autonomous communications to us. If that got confused, we don't have any information about that.

Q. What do we know about what it was doing immediately prior to the loss of communication?

Richard: This started yesterday morning when we were attempting to begin the sol 18 activities. We don't know exactly when but we did attempt to send up commands in the morning to tell it what to do that day. This was while we were doing a high-gain session and the link was a little bit poor at Canberra, we thought because of the rain or station pointing, concerns with SUN alignment. We saw indications that it didn't get all of the instructions and we're pretty confident that it didn't begin the days activities and that's when we started to ask for it to do these beeps to confirm that yes was there and it was receiving us.

Q. Could it have happened the previous night?

Richard: I don't think so because we'd gotten morning data saying everything went fine over night and that it had come up in the morning like it normally does.

Q. In that Australian uplink, did it try to take some of those commands and implement them and created an issue because it didn't get the full commands?

Pete: Our belief that the architecture does not allow that to happen. The command link has a set of error correction codes on it and when it sees single bit errors it can repair those and when it sees multiple bits it rejects those code blocks. The architecture should not build a command set if it does not have all the files there and correct so it should have simply rejected those files.

Q. Can you discount an external event like thermal cycling broke something.

Pete: If you believe that between the HGA session in the morning and when we received the beeps at 1 in the afternoon, that something happened after that beep, the spacecraft was quite quiescent in a warm part of the day with not a log going on. Yes something could break and that's a concern that we have but there was not any obvious correlative event.

Richard: Also true of the MGS link as well. What things that would have to work well. There's a much larger set of things that would allow you to wake up at night and do a UHF session. The fact that the power system and battery have to be working. We think the hardware is working like it's intended.

Q. PL release last night cited similarity to Pathfinder. I'd assume a totally different set of software.

Richard: Operating a lander on Mars is difficult because it's not like a craft in space where you have sort of guaranteed access to it. A lander i snot always visible to you, not always fully powered. We're frequently having to tell it what to do and not sure it's listening to us. That coordination is a place where with pathfinder we had a number of occasions when we sent commands when it was asleep or not pointing at the Earth, etc. That's one of the reasons we have these new mechanisms to guarantee, as much as we can, assured communications.

Q. Location and position of Spirit at the last comm. Standing poised in front of Adirondack? What was the next thing it was supposed to do?

Richard. Same position, in the process of trying to take imaging and Mini-TESS, not RATting yet. Those wouldn't have occurred till later in the afternoon.

Q. What the spacecraft is supposed to do when it's in an anomalous position. Is there a whole sequence, equivalent of hitting the reset button?

Richard: It's very much scenario dependent. There's all these scenarios that we've played out. A number of software capabilities where the vehicle intends to protect itself against a problem, for example if the batteries were in a low-power state, the vehicle software recognizes that and modifies it's behavior accordingly for a few days to accommodate that. We've spend the last hours mapping those out and trying to determine what we'd see. It's not clear that there's one cause that would explain the observables we've seen. That's what's perplexing. The last time we did a full scenario discussion was last night. We've got a lot more information through MGS data plus what happened on Odyssey overnight pass plus what happened today, and now so later this evening we're going to go through and map out what are all the scenarios and what correlates with the observables we've seen and what actions we'll take.

Q. DO you know yet if you'll be doing any testbed analysis.

Richard: We did that yesterday, ran through sol 18 plan. We didn't see anything there that would indicate the problem we've seen. Ther's discussion about doing a little bit more but we don't have information that would allow us to do anything there.

Q. Team is bifurcating with Opportunity and so on. What would be the normal procedure without an anomaly and how it might it be different now.

Pete: We were going to stand down on spirit for 3 days. There would be key meeters of the team moving to Opportunity. We have EDL running on Opportunity. No CM 5, expect no TCM6. We have the next real heavy activity will occur on Friday night about 22 hours, battery de-passivation sequence and we'll get into EDL approach events on Saturday. Heavily scripted. Not a lot of interaction with the ground, requires some selection, decisions. Personnel in common working this problem currently and will have to begin to turn to the Opportunity EDL. If we get into impact to egress there may be other conflicts as well. We don't really have a strong plan yet because we'd like to know more about the range of Spirit possibilities is. We are taking a couple of more beeping opportunities today. We've not confronted those yet because we want to give another day of thinking.

Q. How much of an urgency is there on Spirit?

Pete: If this problem is a software or memory corruption issue and it's not a serious power fault then Spirit can go for a very long time and we can pick up the pieces. If there is a serious power fault, it has life-limiting characteristics and that might be more difficult to recover from. The MGS pass last night is perplexing from all the angles. A lot's got to work so that it works but clearly not enough worked. We would like to have more data from the vehicle, even if it wasn't necessarily good data..

Q. How many working scenarios are there.

Pete: all the different fault scenarios, temp, low-power, software processor recent, interaction with comm. window manager, once you get into software could have a bug or corruption issue and a lot of scenarios.

Q. Are there other external event scenarios, like weather, dust devils, lightning.

Pete: We can't conceive of a local environmental problem that would cause this. We designed for a very extreme environment. The only thing that comes close to that would be some kind of SEU cosmic ray latch-up in the memory somehow.

Q. What had to be working to get the MGS signal. The directional HGA?

Pete: the UHF antenna only, that little pencil shaped antenna, not directional or steerable in that sense.

*Schedule for tomorrow: 9 am scheduled Opportunity landing science brief. 10 am briefing will be update on Spirit Rover.

Pete: Don't take this farther than it deserves go to. If it thinks it's in a fault mode, it's command rate should be 7.8 bits per second. We sent a beep this morning about the time we came in to talk to you. We sent a command that says, "if you get this, send us a beep". I'm told that Jennifer came down here to say we think we got it so that would tell us that the Rover thinks it's in the fault side of the tree. Positive power, some elements of the software are working, x-band is working, sspa, all that stuff is working. That's more information, good news. Need to confirm that. Data from DSN sometimes needs double checking.

Q. When you last heard from spirit. I'm confused about time differences.

Pete: at 7:24 this morning it was 13:31 on Mars, 6 hours 10 minutes ahead. We last heard beep yesterday at about 13:30 Mars time, around 6:30 yesterday morning.
Richard: That was last direct. Then we heard then there was the MGS relay at about 8:30 PM PST about 02:30 am.
Pete: That's separate from this recent unconfirmed report.

*End of briefing*

Posted by asa at January 22, 2004 08:44 AM