But I don't mind that part of it, and neither, it seems, do the attendees. I love Open House, and I really wish I could have volunteered this year -- but I gotta work. Still, I come in early enough to spend a couple of hours walking around and looking at the people. I tend to worry that the space program is supported mainly by older people, with interest fading out among the youth, but I can't see any sign of that by looking at the people around me. Go to Disneyland, come here, it's the same mix; everyone from toddlers to retirees loves the space program. As usual, it's a huge event, with tens of thousands of people coming in -- on everything from motorcycles to tour buses.
Mars in general, and the rovers in particular, are especially popular. JPL filled the 303 cafeteria with Mars stuff, including the ever-popular exhibit where a bunch of kids lie prone on a mat and a volunteer drives a small rover over them. The kids love this. Love it. LOVE it. I'd like to try it myself. I think when you come out the other end of the line, you can go into the ISIL and see the sandbox (our testbed), but I'm not sure.
The line into 303 is huge, and it snakes past a bunch of posters documenting the history of Spirit and Opportunity. One of these posters shows our RATting at Mazatzal. This is my favorite, because it helps me put things in perspective. At the time, I felt so awful about my bad performance at Mazatzal, and in the end it doesn't matter: we got the scientists the data they wanted, and they're even bragging about it to tens of thousands of people today. So things you feel lousy about can work out fine.
As the line progresses, it also winds past an open area where they've put several rover models on display. And they're driving one of the testbed rovers around in it, so that people can see for themselves how the rovers move. Mark Maimone is standing there with a microphone, capably answering questions from the audience. As he finishes answering one question, I go up to him and ask another: "Who are those handsome guys who drive the rovers?" Mark laughs and introduces me to the crowd. I spend a few minutes chatting with a visibly impressed family, and then fade back and let Mark have the show. (Nagin tells me she stepped into that area to answer a couple of questions and didn't get out again until four hours later.)
On second thought, maybe it's just as well I didn't volunteer for Open House this year. I think my ego would explode.
I run into Bob Deen, who has a story of his own about International Legal Affairs (the dorks who spoiled my Canada trip). A little while back, he wanted to release for public use some software he'd developed at JPL. The software got to ILA -- and sat there. And sat there. And sat there. At long last, a specific customer for the software started asking for it, and Bob had to get his section manager involved to get ILA to rubber-stamp the damn software release already.
The whole process took over six months.
Today's downlink is delayed again, just like yesterday. So Art decides we're not even going to try to IDD. "It's a touch-and-go sol without the touch," he says. So it's an "and-go" sol, I guess. I left Open House in plenty of time, but I've got another 30-45 minutes to twiddle my thumbs before the delayed data actually gets here.
During the lull, Larry Soderblom plays an audio clip of John's call-in on the NPR show "Car Talk." I'd been offered this interview, as it happens, and turned it down because it was scheduled for a time when I'd be working. So they offered it to John -- and then rescheduled it, so I could have done it after all. Oh, well. John does better with it than I would have, anyway.[1] The idea was to call in as if we needed some car advice, and slowly reveal that we were talking about a Mars rover. I had come up with an idea that they didn't use. ("How old is your vehicle?" "Less than a year." "And how many miles on it?" "About three hundred million ....")
Anyway, John soon reveals that he's talking about the Mars rover, and they pretend to be surprised, and then they talk about the rover a little bit. One of the hosts asks John, "Why not drive this thing every day like tomorrow something catastrophic could happen?" Mark Adler, listening to the recording, responds immediately: "Mission Manager thinking!"
We might drive backward thisol. Joe Melko raises an old argument, that if the rover's going to collide with something, it's better for the rear of the rover to make contact than the front. This is because the rover has enough strength to push hard enough on the (front-mounted) IDD to fatally damage it. But the body of the rover, which would make contact in a backward-driving collision, might be strong enough to survive.
On the other hand, if we're wrong about that and the body of the rover were pierced, the rover would soon freeze to death. Better to lose the IDD than the whole vehicle. But as an experiment, we decide to drive backward thisol anyway.[2]
At long last, we start to get data. Six whole minutes' worth. Scott Doudrick tells us that's all we're getting for a while: next, there's a priority table change that interrupts the stream for 35 minutes. After which we get 30 minutes' worth of additional data before another 15-minute gap induced by a Deep Space Network station handover. We've really got to start getting our data into the queue ahead of Opportunity.
So, so far we have only the HAZCAM images. John and I are content to wait for the downlink, but Larry Soderblom's getting antsy and prods us to do something. So we make a basic plan: we'll drive blind a few meters, up to the limit of the HAZCAM data, and then autonav after that. We choose a couple of autonav waypoints so that we can turn one of them into a blind waypoint later, if we get the NAVCAM data soon enough.
We also back up again today at the start of the drive, like yesterday. Today it's for a different reason. There's no hazard in front of us, but autonav left a 15cm rock right next to the left front wheel, under the rover's body. This is likely safe, but we don't like it: there's a wheel strut just next to the rock, which could theoretically cause a problem, and it's possible for a rock to damage cabling under there. We can avoid all of this by just backing up and driving around the rock -- and what the heck, we have plenty of time. So we do that.
One thing that's good about this rock: it means we didn't give up anything when we decided to drop the "touch" part of thisol's "touch-and-go" plans. We dropped it for time reasons: because we wouldn't have time to plan the IDD work in addition to the drive. But with that rock in the way, we wouldn't have been able to safely deploy the IDD anyhow.
At long last, we get more data. Yestersol's drive was a decent 53m (40 blind, 13 autonav) -- not great by our current standards, but I remind myself again that we would have killed for a drive like this not so long ago. John has to leave so he can get ready for his early-morning flight to Montreal, so the rest of the sequencing is up to me. I don't mind that at all, of course -- it's almost like being an RP-1 again.
We have NAVCAMs, so I'm able to push the blind drive out about 30m farther. This takes us over a gap in the mesh, but I check out the terrain in the raw images, and it looks perfectly safe. Art asks me to cut the drive short before the gap anyway, though -- he wants to play it extra-safe since we only have one RP available. I know the traverse is fine, but I don't want Art to have to lie awake worrying about it, so I cut it short. A few minutes after that, we get the PANCAM mesh, and the PANCAMs fill in the gap -- so Art drops his objection, and the blind drive is extended once more.
Mark Maimone explains Mars rovers to admiring visitors.
The endless line snakes around the Mars exhibit.
The first thing that made me feel any better about Mazatzal.
Giggling kids get run over by a prototype Mars rover.
Footnotes:
[1] Just as a measure of how well John did, I still occasionally run into people who remember that interview.
[2] The rovers were originally designed to drive about equally well backward as forward -- in some ways, they drive a little better backward. It's amazing how long it took us to get comfortable with the idea of driving backward, though. From my current perspective, I see that we took some time to really learn to think like the rovers.
Posts
1 comment:
I always suspected that driving over children was educational.
Post a Comment