NASA EDGE: Mars Yard
NASA MSL Team Members
- Paollo Bellutta
- Martin Greco
- Jaime Catchen
BLAIR: Okay, if the rover operates autonomously…
PAOLO: Yes. Why do I get paid?[Laughing]
BLAIR: Well, do you just come in every day and just say, yeah, it drove.
PAOLO: Actually, preparing the commands for the vehicle is pretty easy. The difficult part is being a pessimist, It is imagining all the possible wrong things that can go amiss and prevent the vehicle from getting into those situations. The first thing we want to do is to make sure the vehicle doesn’t get into trouble. Make sure the vehicle is capable of detecting unsafe situations. The second best thing that we can do is autonomously have the vehicle determining potentially unsafe situations and avoid them, so you can continue driving. But if the fist law of robotics is to fail, in this case, that is if it cannot find autonomously a safe path to go, it will simply stop and ask us for help.
BLAIR: I thought the first law of robotics was don’t attack humans.
PAOLO: Um, at the moment we don’t have any humans on Mars.
BLAIR: Oh, good point.
CHRIS: So Martin, you’re the Lead Flight Systems Engineer for MSL.
MARTIN: That’s correct.
CHRIS: You’ve got a pretty important job.
MARTIN: It is pretty fun.
CHRIS: What’s that all about?
MARTIN: It’s making sure the avionics and the flight software play together. And we also have to command the vehicle, and make sure the whole ground system can communicate to avionics and the flight software to ensure we can get EDL done correctly.
CHRIS: As a flight systems engineer, take us through that process of what you are you trying to look for in the data as it enters the Martian atmosphere?
MARTIN: Before we get into the seven minutes of terror, about forty minutes, we start prepping the vehicle for EDL. At that point we have lots of telemetry telling us how it’s doing. We give our last pole. We’re good to go. We’ll put it on its way. Let’s stop commanding it. About 10 minutes from entry, we do our cruise stage separation. We get rid of the cruise stage that got us there. Get our thermal batteries ready; make sure that the vehicle in its encapsulated form will get us down.
MARTIN: But at that point there’s a flight software called the EDL timeline that works in concert with the guidance and control to make sure those last minutes are very scheduled, basically all the way down.
CHRIS: At what point is it fair to say you’re pretty confident that MSL has landed safely and that it’s ready to go.
MARTIN: It takes about 20 seconds for the descent stage to fly away. The descent stage will bring us down to touchdown. It will internally go into it’s own control mode and fly away about 500 meters. That takes about 20 seconds, so we’ll basically be waiting a little bit after touchdown to make sure everything is happy and healthy.
CHRIS: Do you have any interoffice pools to determine where that descent stage lands on the surface?
MARTIN: I think we’re going to end up having something like that.
JAIME: I’ve been helping the EDL team in the past four or five months doing stress and robustness testing. We actually throw a ton of anomalies into this test we do, testing the sequence of events that occur for EDL approach and EDL. We’ve thrown some crazy anomalies at this thing and it’s been able to land.
CHRIS: What are some of examples of those anomalies that you’ve thrown at MSL?
JAIME: In the tests we’ve been doing during the EDL approach phase, some examples will trip different fault responses. Either temperatures are too hot or too cold somewhere and the flight software has to respond to those things. We’ll even inject having a computer reset and make sure the system can recover itself and still land safely.
CHRIS: Has the rover done a pretty good job so far?
JAIME: Yeah, it’s amazing some of the things we can throw at the system and it’s still able to land.
BLAIR: You’ve obviously been out here in the Mars’ Yard practicing but right now Curiosity is in route.
BLAIR: Are you guys going to go into hibernation days before the landing so you can be up for all the intense activity once you land successfully and begin operation?
PAOLO: I don’t know if I am going to be able to sleep.[Laughing]
BLAIR: You’ll be where when Curiosity finishes those seven minutes of terror and it starts operation, where are you going to be?
PAOLO: Um, I get to be part of the team that’s going to localize the rover. That is try to find where on Mars the vehicle has landed exactly.
BLAIR: Like Google Maps when you hit the little button and it locates you.
PAOLO: Yes, the fact is we don’t have streets. We don’t have street names on Mars.
BLAIR: Roads, where are you going? You don’t need roads.
PAOLO: We don’t have a GPS there, so the vehicle is not going to tell us immediately where it has landed. It is going to give us some idea. It is going to give us some clues. There is going to be some telemetry, some images. Potentially, it’s like trying to find a needle in a haystack.
CHRIS: Wasn’t it true that the Spirit and Opportunity that the air bag system was actually at its limit in terms of mass?
MARTIN: Yeah, pretty much. There was lots of testing. The testing that was done showed that. The mechanical guys went through an ice tray and showed there is no way we can do this. The forces are just too strong. The airbags will get torn to shreds. In sky crane we traded mechanical complexity of MER for the guidance control complexity with the sky crane system, which is a huge mass saver. Now we can land something as large as MSL rover. On MSL, making sure this thing works required a lot more people. The team has ballooned. You’d imagine with a larger team you would have full coverage but given the complexity of the system, we’re still trying to make sure things are all pieced together, make sure all the check boxes are checked, and everything is ready to go.
CHRIS: It makes your job even harder because with a vehicle this size, this is just a scarecrow.
CHRIS: This is not the total vehicle. But imagine a rover this side has never even attempted to land on the planetary surface before. It’s going to be the first time. This is going to be a record.
MARTIN: It will be, 900 Kg.
CHRIS: Absolutely. Probably even the Guinness Book of World Records. You need to call them up. From your perspective, your job, now, just magnifies as the Flight Systems Engineer on MSL compared to MERS.
MARTIN: Right. This just becomes a lot more… what’s the word? Scary.
CHRIS: You had mentioned the spacecraft is constantly awake since it left the air surface and heading to Mars. Is it on medication this whole time to stay awake? How is it able to stay awake 24-7?
JAIME: It has solar rays, so that helps some.
CHRIS: Do you have engineers staying up 24-7 to make sure it’s responding to the spacecraft?
JAIME: In a few days after launch, we did have 24-hour operations going making sure our new baby spacecraft has people watching it. The last probably 9 days prior to EDL, we are going to have people watching it more closely, 24-7 but for the most part we watch it once per day. We’ve got coverage with our antennas here on Earth to get telemetry from it for a chunk of the day, usually every workday; engineers that look at the health and status to make sure it is okay at that point in time. Then we’ll say, see you tomorrow.
CHRIS: We’re watching you live right now on our NASA EDGE webcast. If you’re not here, you’ll be in the control room, right?
MARTIN: We’ll be in the control room around now.
CHRIS: What are you feeling right now?
MARTIN: I’ll be scared, a little nervous but knowing we’ve done everything we can to make sure this thing is ready to go. Having that peace of mind, hopefully, it’ll be down in a couple of minutes and happy.
CHRIS: You’re working on such a complex piece of machinery. If something does go wrong, what can you tell these up and coming engineers what to expect when you’re working on projects as complex as this?
MARTIN: There’s always something to learn even if it goes right or wrong. So, you’re going to learn something. What you learn if something goes wrong is how to do it right the next time. We’ll have opportunities in the future to do this again. And if we do fail, we will go to Mars again. Hopefully, in the event something goes wrong, we will do it better the next time.
PAOLO: There is something the Hum-V cannot do.
BLAIR: All right.
PAOLO: Which is to turn in place…
BLAIR: Oh yeah! Nice! All right, that brings up another question. How long before this technology can be implemented in my Honda Accord? I hope sooner rather than later because I’d just like to relax and drink coffee while I’m driving. It’s obviously safer if it’s autonomous.