Wednesday, July 20, 2011

Where We Stand Now — Current Rover Status

Right! So! Ok! Time for something to chew on.

Status of Opportunity: Fat and happy. Minus the fat (her diet is mostly carbohydrates and protein). Also minus the happy (she's a robot, she has no emotions but cold-hearted reason.)
The more technical way of saying it: She's GREEN.

Since it's the topic of interest to the audience, I'll mention two important milestones have been achieved just within the last week:

1) Oppy crossed the 20-mile odometer mark. That's 32186.88 meters. The drive that achieved this — sol 2658's drive of 125.2 meters pushed her past this mark, and ended at the 32207.63-meter mark.
2) Oppy is approximately 1 kilometer (0.62 miles) from the official "landfall" at Endeavour Crater.

Number 2 is an item that has been on the team's radar for quite some time. There are several interesting items that we must know about this crucial "status item." First, it's somewhat ambiguous: the crater's edge is not well-defined; and it's dependent on the definition of the so-called "Pink Path." Since the departure from Santa Maria Crater in March, the Pink Path has been a strong focus in long-term planning. As we truck along in tactical operations, the scientists and mission planners constantly refine this Pink Path to define, when we get to some given spot, where we ought to drive. It is focused on avoiding obstacles (think of the "Purgatories" that caused the team to make Oppy drive west — away from Endeavour — a few hundred sols ago) and on science targets (think of the infamous "Approach Crater").

Continuous ouches here and nudges there have caused some headaches — the RPs end up with multiple Pink Path sources from which to plan drives — but these headaches are few. This Pink Path is not a straight line, so calculating the distance to Endeavour is a little more Arduous. The coolest bit, though, is Ohio State's (led by Ron Li) calculation of this distance as well as the "countdown" to landfall. After every drive, they plot the ending position of the rover and the "percent complete" number. This second number is the percentage of the distance (via the Pink Path — not as-the-bird-flies) between Victoria and Endeavour. Really cool to watch that number go down. This number, displayed with the distance left, gives us the infamous "[Larry] Crumpler Countdown." Currently…

Crumpler Countdown (-up) to Endeavour (07/20/11): 1.0km, 95.2%

Yeah, boy! Until landfall — a month or so, depending on whether or not one is Steve Squyres ("pedal to the metal") — I will update the Crumpler Countdown after each and every drive. By the way, in the queue for sol 2662: 55 meters. 

(Feels a little low, right? We've been blowing by with drives of 120+ meters in the last few sols, so what gives? For sol 2662, it was a combination of the science team wanting to stop short for the next crater set [Stu: it's named Mariner 9! They have a name!] and being limited by the data that had been downlinked by the time the drive needed to be planned.)

The only other really important engineering status item — thought I can feel the rest of the engineers itching to say something about their subsystem — is power:

Power is an item that we constantly model and watch. So much so that it is a critical-path tactical operations decision point. (I often wonder how many lingo terms I can put into a single sentence. My current record is 12.) As the Opportunity Updates webpage tells us, on sols 2627 and 2628, Oppy benefitted from a series of dust cleanings. We were able to support overnight (Mars time) relay communications with the Mars Odyssey orbiter, a rare oddity; we always get the relay in the afternoon (Mars time), but the chance to get back roughly twice the data is always great. The problem, though… Tau (atmospheric opacity) is on its way up as is expected for this time of the Martian year. The reduced dust on the arrays roughly cancels the effect of the dusty air, so we're currently only supporting standard, single-relay operations per sol.

There are the usual concerns of data management (how much is onboard? how much has been sent? how much can we delete? how much will we be using? how much will we be downlinking), thermal (more pre-drive heating, less pre-relay activity), and actuator wear-and-tear, but we'll tackle these tactically and as we run into them.

This blog is about to take a head-first dive into the tactical deep: I've actually been on vacation in Colorado since last Thursday, and I've been popping these posts out from a comfortable couch! Next Monday, when I return to JPL for the daily grind, I've got myself 3 tactical shifts next week. 

Boom-boom-boom, 1-2-3, right in a row. 

It'll be a little crazy. I can feel it already. I'll have to brush off my 10-day-worn skills.

Until then, a few more days of vacation and 16 hours of driving through sandy nothingness.


Anonymous said...

Mind if I ask something I've wondered about before? How is the drive distance calculated so precisely? Measurements from MRO or some other satellite? Or actual rover instruments? Thanks...

Matt Lenda said...

In the most general sense, we use recorded data from the rove; essentially, how many times did the wheels rotate? That's easy compute. There are other gotcha's, like if there's slip involved, or if the dirt is rock hard and not sinking due to the weight of the rover, or other stuff... and our software takes into account all of that.

Jaime C. said...

Matt, They also use MRO (HiRISE images)!!!! - Jaime

Jaime C. said...

The team does use the MRO images as well. Tim Parker...

Jaime C. said...

The team does use the MRO images as well. Tim Parker...