Monday, December 12, 2011

100 Sols on Cape York — An Absurdly Brief (Read: Long) Summary (Part 1/8)

Just as you might expect for a young-gun Generation-Y'er, I'm wired. I use my iCal, Mail, and everything else in my Macbook to manage my world. ("Manage the crazy. Bring out the talent.") I need things to be organized, so rightly placed and micromanaged that it would make a normal person wonder how (or why) I'm not on Ritalin. However, I have one holdover from the olden days. That holdover?

The notebook.*

Don't get me wrong: I am a fan of TextEdit and other flat-text, note-writing programs. Who needs all that markup, right? But there are so many places to put files that you forget not only what you named the file, but what's in it. With a notebook, it's all right there, ready for consumption, with perhaps a little page flipping.

I have several notebooks for work. First, one for all my multi-mission work — you know, the Juno's and MRO's of my world. It's got scribbles and notes and it's a total brain scatter. I love it. Organized, but not. Second, one for logging my days. Like a work journal, but abbreviated and totally half-hearted. I tend only to log the more important days, because those days are usually filled with actual work and I have less to write ("7am: MER shift. 7pm: Sequence model development for MSL.") Third, one exclusively for MER. I never kept a MER notebook until I felt it was important enough. That time, that crossing the threshold of "important enough," was when we hit Endeavour Crater. Rightly so, the notebook is named "The Endeavour Campaign." 

This notebook serves the purpose of reminding me of what I did on each of my shifts — new tricks, bug fixes, engineering tidbits, that sort of thing. I never thought it would turn into the monster that it did. A few weeks ago, someone asked me a question to which I had the answer in my notebook; I couldn't remember where it was, so I started flipping the pages. "Geez, it's right here, gimme a sec… Hang on, I know I'm close… Man, I've written a lot…" 

As it turns out, "a lot" is about 100 pages in 100 sols.

Holy crap, we've been here 100 sols!

To drive it home further, a former-colleague-and-classmate-now-new-colleague-and-MER-TDL-in-training-and-drummer-in-my-Sunday-jam-sessions friend asked me today, "So I've seen all the news stories about the Gypsum find, but nothing yet from your blog. What gives?"

Well, trees give. They give very easily, in fact. He understands my pain, though: we both experienced 50 hours without power at our respective houses. Even so, this blog has been empty for most of December. What else has been going on? 

This post, is what!

I've been prepping this post for a few weeks. I have this uncanny ability to steal pictures from the various Cape York UMSF threads and Stu's blog. By steal, I do mean borrow with credit (Stu said I could! I swear!). I also have this uncanny ability to be incredibly wordy. So, onward!

(Courtesy Dr. Awesome XVII)

My intent is, as always, to provide context and insight into what happened these last three months. You can expect a little chaos here: 8 parts, each with the intent of informing people who aren't so in the loop as some of us are. The purpose is to be a summary, so if you know what happened, don't spoil it you crazy goons.

(Remember: For full-size images, click them!)


Part 1: The Approach to Endeavour Crater

[forever ago] to ~2680
"tl;dr" Description
We drove for, like, ever.
Highlights from Matt's Notebook
[No notebook! Boooo!]

Details ("the deets")
About 1000 sols ago, the Opportunity rover was commanded to drive away from the Victoria Crater. Having expired her manufacturer's warranty nearly 20 times over already, the team said, "There's this large-ish hole in the ground, way over there, so let's go. Who knows?" 

When describing this new mission for Opportunity, Project Manager John Callas could make no promises for when we'd arrive at Endeavour. It was 19 kilometers away (not quite as the bird flies) — more than Opportunity had already driven in its 1700 sols on Mars. And there was all this stuff in the way, like the Purgatory dune field and small craters and rocks everywhere. His — the team's — best guess was, "When MSL lands in 2012. Maybe." Our target was this little guy on the west side of Endeavour, named Cape York:

(Ignore the red circle on the second image.)

For an idea of the size of Cape York, check out Stu's post. That third image is a perspective view looking roughly north, giving you an idea of how it bends in towards the center of Endeavour. Spirit Point was the destination, the small Odyssey crater being a nice landmark for us to shoot at.

Somewhere in that journey, near sol 2310, I joined the MER team fresh out of school in Colorado. From the start, I noticed this curious little countdown meter in the LTP (Long Term Planner — someone who represents the SOWG) reports when the most recent traverse was shown in aerial imagery from the MRO spacecraft. This countdown meter counted down the distance from Victoria Crater to Endeavour Crater. The number was in the mid-40%'s when I joined, and that last 55% was a seemingly insurmountable task. We chipped away, little by little, and suddenly that number was 80%… 85%… 90%… All we would see in the LTP reports were images like this:

Very tantalizing. "What's it really going to be like when we get there?" we found ourselves asking.
Then we did this whole thing: 

And we did it a year ahead of schedule. Neat.

To capture the journey, I spent a few hours going back through every LTP report since sol 2310 and picked out a traverse roughly every 10 sols to build a "distance traveled" plot. (The maps posted at the MER website don't have the detailed Ohio State maps with the countdown meter as often as I need them. The information could also be found in the Google Mars maps that Stu and company make, arriving at the same answer.) This plot? Oh yeah, it's right here!

Several things here: 
> I layered in text annotations of targets and key events to give us some context.
> The left-hand side (blue line) is the percentage from Victoria to Endeavour ("V2E") according to the Ohio State traverse maps. 
> The right-hand side (green line) is the distanced remaining, derived from the V2E line.
> Not all meters are created equal. More on this in a minute!

Cool, right? ("Right!") 

The obvious trend in here is rough, linear progress. The other obvious trend is the long stop at Santa Maria for an extended science campaign and Solar Conjunction, or when the Sun gets directly between the Earth and Mars, from December 2010 through February 2011. Also, note the other key events. My favorite is what I'm calling the "Squyres Week," when Steve Squyres came in on a Monday and said, "I'm SOWG Chair all week and I want half a kilometer by the end of the week." Sure enough, that week's Mission Manager report proudly toted nearly 600 meters of drive distance in 5 planning days. 

Now, some explaining is in order. The distances reported in the were based on the so-called "Pink Path," which changed as we approached Endeavour. Therefore, I say the phrase "not all meters are created equal." Meaning, a given meter of progress towards Endeavour is not the same as another meter of progress at some other point in the journey if the Pink Path changed. Which it did — a lot! The arrival point was always Cape York but the twists and turns between Victoria and Cape York changed quite a bit.

We get a notion of "speed" (literal meters per sol) of the rover by looking at the slope of the "percentage progress" line (or the negative of the slope of the "kilometers left" line). We see that before and after the long hiatus at Santa Maria the slopes of the line is generally linear and about equal. We were just a little bit more of the "PEDAL TO THE METAL, BABY!" persuasion after Santa Maria, so why does it seem we did the same meters per sol as before Santa Maria? Because the Pink Path got longer! A given meter of progress after Santa Maria was not the same as before Santa Maria, because the SOWG got together and picked all sorts of cool little targets along the way.

(A way around all of this is to use actual drive telemetry — actual distance traveled every sol — to get a better notion of speed. But that's proprietary and painful. No thanks! Plus, the "V2E" count up is a little more fun to look at.)

Right. So. Speed. (I almost typed "velocity", but, you know… it's not that.) Why don't we just take a look at that directly? Ok!

Indeed! The speed shows up a little more obviously larger in this figure. There are two trends: first, an increase in speed — an increase in us wanting to get to Endeavour; and a cyclical "up down" pattern along this linear increase in Endeavour-wanting. That increase in speed was enough to overcome the effect of the Pink Path increasing in length! That's fast.

But, why is there a second trend? Why does it wobble? Shouldn't it be prettier?

No! Of course not! That pattern is, nearly precisely, the cycle between Nominal and Restricted planning! Remember: in Nominal, we can plan a drive every sol because the timing of uplink and downlink sets us up to know what happened before planning tomorrow; in Restricted, we can't plan a drive every sol — more like every other or every third sol — because we don't have "ground in the loop". I found this fascinating, if not completely ultra cool.

(Also, ignore that noisy large bit at the end. That's an effect of the Pink Path changing more wildly and our indicator of "progress" breaks down. The rest of the values before that noisy bit square nicely with approximations reported daily at our tactical meetings -- "assuming 65 meters per sol" was a common phrase towards the end!)

Along the same vein of "progress" indicators, here's a series of four high-resolution Pancam images of Endeavour from sols 2410 to 2681 (skewed towards the end of the timeframe because I'm lazy):

Then we have the famous Navcam Movie, another indicator of progress for the entire journey. And, as noted in the progress plot above, there was the appearance in the LTP reports of the vertically-exaggerated "Endeavour 'Fall Away'" GIF that I found on UMSF:

Hey, you know, that picture was an event in itself to me because suddenly Endeavour had opened up, like HEY EVERYBODY, EVERYBODY HEY. Simply stunning.

So what, right? We went a long way and we have all these great things telling us about the journey. Then? Then what, Matt? Is there something to the end of this story?

How about this: You all quiet down and stay tuned for…

Part 2: Landfall at Endeavour Crater: Cape York and Odyssey

(Tomorrow, maybe!)


*Not the movie. Oh god, please not the movie. Anything but the movie. I kept this phrasing because it feels so, I don't know, poignant. Or something.


Buck said...

This is made of awesome!

JoeRanch said...

Really like that Fallaway view!!

Stu said...

VERY cool, looking forward to reading the rest! :-)