What I Learned Today

I recently joined the Mars Exploration Rover team as a TAP/SIE (Tactical Activity Planner / Sequence Integration Engineer) for the Opportunity rover. That means it’s my job to sit in on the morning SOWG (Science Operations Working Group) meeting, in which the rover’s scientific goals for the day are set, and then work with payload, thermal, downlink, mobility, and other experts to come up with a plan to achieve those goals. What pictures will we take? When? Where will we drive? Is there enough power?

Reading the training documents only gets you so far. I’ve just begun “shadowing” the current TAP/SIEs so that I can learn on the job, watching over their shoulders through a day of planning. My first shift was on Wednesday, and it was supposed to be an “easy” day: pick one of two rock targets, drive towards it, and take some pictures looking backward at yesterday’s tracks.

Scientists dialed in from all over the country for the SOWG meeting. After some debate and consultation with the Rover Planners, they settled on the rock that had the easiest approach. The scientists signed off and we went to work building the plan.

The TAP/SIE’s job is facilitated by a bewildering array of scripts and tools. These allow for the setup, development, refinement, and checking of the plan. Are power or thermal constraints violated? Do we have enough onboard storage space for the new images to be collected and enough downlink allocation to get them back to Earth?

While the RPs (Rover Planners) settled in to their job of constructing the drive sequence, we worked on the full sol’s plan (a day on Mars, which is 24 hours and 40 minutes in Earth time, is called a sol). Very quickly we realized that the planned drive, despite covering only a couple of meters, would drain the rover’s battery dangerously low. Opportunity was starting the sol at only 80% charge because of two long instrument observations the previous sol.

We modified the plan to give the rover a morning “nap” in which it could sun itself and collect power, like a desert lizard. That helped the power situation, but not enough. Several iterations later, we finally squeaked by at 0.1 Amp-hour above the required threshold.

Meanwhile, the RPs were growing concerned about a different problem. To reach its goal, Opportunity would have to straddle a rock that, while small by human standards, could pose a risk to the rover’s instrument arm, which dangles slightly down when stowed for driving. The RPs put their 3D simulation of the rover and the terrain up for all to see, and we stared at the screen while they spun the rover and tried to examine the rock from all angles.

“Can we raise the arm while it drives over the rock?” I whispered to the TAP/SIE I was shadowing. “It’s risky to do that,” she whispered back. “The arm bobs around, especially going over a big rock.”

A few minutes later, a scientist on the telecon asked, “Can’t we just put the arm up?” but was quickly shot down by the TUL (Tactical Uplink Lead, head planner): “Too risky.” The TAP/SIE and I grinned at each other.

Ultimately, it was deemed too dangeous to drive over the rock with our current data (images the rover had taken the sol before), and they decided to drive up to that rock and stop. Post-drive imaging would illuminate the obstacle in more detail.

At the end of our shift, which apparently was two hours later than usual, we had a plan. We ran it through multiple checks and re-checks and manually confirmed all of the sequences. The final walk-through was punctuated with “check!” coming from different areas of the room as each person confirmed that their part was correctly represented. The plan was finalized and transmitted to the rover using the Deep Space Network later that night.

There’s nothing like seeing a job in action. I learned a lot about the steps involved in planning and (unexpectedly) a lot of re-planning. For the rover, today is “tosol” and yesterday is “yestersol.” I got to practice the phonetic alphabet, which is used to communicate letters (in rover sequence ids) with a minimal chance that they will be misheard. I even got to help out a bit as a second pair of eyes to catch typos, spot constraint violations, and suggest alternative solutions. And I’ll be back on shift next Monday!

Opportunity is near Endeavor Crater, working its way along a ridge that is at the perfect tilt to keep its solar arrays pointed toward the sun. This is important because Winter Is Coming, even on Mars, and we want to keep it sufficiently powered to make it through to spring — its fifth spring on Mars. (Opportunity landed 9.5 Earth years ago!)

I slid into the driver’s seat of the Tesla Model S with eager anticipation. Would it live up to all the hype?

Yes.

This is a car the way cars should be. The fact that it’s also an electric car catapults it into the realm of Sublimely Awesome, but even without that it would be a thing of beauty and utility. Everything in it works. The touch screen is responsive. The user interface is simple, clean, and beautiful. The sun roof is generous, the passenger space expansive, the cargo space eyebrow-raising. The seats are comfortable, the ride is smooth. The backup camera view is cinematic. Really, there is nothing NOT to like about this car. It’s practically the Platonic ideal of a car.

Here’s the dashboard, which consists of a simple customizable display in front of the wheel and a simply IMMENSE touch screen in the center console:

You can’t imagine how huge this thing is until you sit down next to it. It’s the size of a legal pad. However, it is often used in split-screen mode (as shown here) to give you, effectively, two displays. Its response is never jumpy, just smooth. It has magical powers, like a touch slider that opens the sun roof to the percent specified and other touch buttons that let you change the suspension of the car, while driving.

Oh, speaking of driving: this car moves. At the free way on-ramp, I was warned to put both hands on the wheel, “because it takes people by surprise.” Boy, did it! You press on the accelerator and it leaves your stomach behind. I didn’t even get to floor it because we were already at the top of the ramp going 60 (zero to 60 in 4.2 seconds!) and I didn’t want to ram the cars ahead of me. I got onto the freeway and tested the acceleration from a starting point of 70 mph. Zoom! It *still* took off with the same unnaturally intense pickup (unnatural today because we don’t expect that from a car. BUT WE WILL.).

The Tesla battery design is a leap ahead of the other electric vehicles on the market. It is composed of 8000 individual lithium-ion batteries, each about the size of a AA battery. Loss of individual batteries doesn’t affect the overall performance, and Tesla (the company) constantly monitors your battery status and contacts you to bring the car in if there are failures. The batteries are liquid-cooled and therefore perform much better, especially on hot days, than other electric vehicles that use air-cooled batteries. The Model S also has a range of more than 250 miles, handily addressing range anxiety.

I still can’t bring myself to spend $62,000 (after rebates) on a car. But I’m almost persuaded that this car is actually worth it.

Yesterday I took my first acroyoga class, which was held at the Laughing Frog Yoga studio.

We started with headstands, which I’ve been learning to do with the assistance of a wall. This time we did it without a wall but with a partner to spot. We were instructed to start in crow pose (picture from the web, not of me):

Next, you place your head to the mat and rotate your hips up to go into a headstand.

This is hard.

It was the first time I’d done crow pose, which is a nontrivial exercise in balance. Then I got my head down to the mat, but I couldn’t rotate my hips all the way up. So I started over and did it the way I’ve been practicing: bend at the waist, put your head on the ground, and rotate your legs up from that point. This is much easier, mainly because your waist starts higher.

In the handstand, we adopted a straddle pike position, which means legs apart in a V and hips bent so your legs are in front of you (not straight overhead). We then practiced flexing the sacrum to learn how to rotate the legs forward and back without tipping your weight forward and back. Why? Because “once you’re doing this on top of someone’s feet, you don’t want to tip off onto the floor.”

Of course.

Next we did a “back flying” sequence, which means the flyer (person on top) is on their back above the base (person on bottom). In theory this is scarier, since as the flyer you can’t see the floor. In practice, to me it feels the same as any other pose where you’re dangling in the air on top of someone else’s feet. Here is an example somewhat like what we did:

Then we did a “chi machine” in which the base supports the flyer’s shoulders with his/her hands and shifts his/her feet to inside of the flyer’s knees; the flyer then folds at the waist into a very relaxed pose. Surprisingly comfortable.

Then the flyer rotated slowly into a “straddle bat” position as the base worked his/her feet around the flyer’s hips. It looks like this:

We then practiced going back and forth between back flying (base’s feet under flyer’s sacrum) and straddle bat (base’s feet at flyer’s hip fold).

Next we went higher, into star position:

As the flyer, you get here by grasping the base’s hands, ducking your head down to place your shoulders on the base’s feet, and leaping up into a shoulder stand. The base brings his/her feet together behind your head, and you press your head back into his/her shins to lock yourself into place. You also still have the hands to help balancing. :)

I got to serve as the base and flyer for all of the moves! Being the base is harder for me, because I get scared that I will drop/hurt the flyer due to my beginner status. My side-to-side control is weak. But when it works, it feels awesome :)