How We Decided

togglesbloggle:

The day after tomorrow- that is, February 18, 2021- the Perseverance rover will attempt to land on the surface of Mars.  It will enter the planetary atmosphere at an acute angle, giving it as much time as possible to experience drag and slow down from orbital velocities.  Because Mars’ air is so thin, and the rover is so heavy, this will fail- in the best case, Perseverance would still be going almost a thousand miles an hour when it impacts the surface.  To help save itself, the craft will deploy a parachute of advanced design, seventy feet across and able to withstand supersonic velocities.  This, too, will fail.  Even with a parachute, there is simply not enough air between Perseverance and the Martian surface to slow it down all the way.  So this is where the rockets kick in.  Once air resistance slows the rover to a bit less than two hundred miles per hour, the heavy heat shield will be jettisoned, and a system of secondary rockets will fire against the direction of motion until it slows to near-hovering.  In a final flourish, the rover will descend from the rocket-boosted frame on coiled springs, until it touches down in the western part of Jezero crater in the northern hemisphere of Mars.

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As it happens, Perseverance’s destination was one of the very last things we decided about it- not until the craft itself was fairly thoroughly engineered and designed.  Formally, the decision was made by the mission directorate.  In practice, they follow the consensus of the scientific community, which in turn hashes things out at a series of open-invitation workshops.  Things began with a call for white papers- an open suggestion box, basically.  In 2015, the first workshop narrowed things down from thirty serious proposals to eight candidates.  In 2017, the second workshop further winnowed the list down to three.  And in October of 2018, after three days of presentation, debate, and discussion, the final workshop selected Jezero Crater from these final three candidates using a simple vote of all attendees, and passed on the recommendation to the mission leads.

I haven’t been in the business for very long, so the final workshop was the only one of these where I actually participated.  It wasn’t a close vote as such, and I didn’t break any ties, and technically we were just making a strongly worded suggestion.  Nonetheless, my vote is one of the reasons why the Rover will be going to Jezero Crater instead of Syrtis Major or Gusev, and I think I’m entitled to feel ownership of this mission choice, just a little bit.

(This is, of course, terrifying.)

Having gone through the experience, there were a few surprises worth noting.  The first was how small some of the numbers are here.  The conference was not very large: only thirty proposals, debated by just a few hundred attendees.  I’ve seen book review contests with more entries, and that are read by a wider audience.  Which is to say, this is a situation that was, and is, extremely responsive to individual effort.  In that small a room, populated by people that are philosophically committed to changing their minds when they see good evidence or a good argument, one person can stand up and change the future in a very real way.

The second surprise was the attendance requirements.  Or rather, the lack thereof.  The project is public, paid for by American taxpayers, to whom I am profoundly grateful.  And one way the process reflected that public-spiritedness is that this is not a walled garden.  A small attendance fee (iirc, $40?), and you’re in.  You get a vote, if you want to use it.  A few non-scientists even took us up on this; there’s one retiree (a former schoolteacher, I think) that’s attended every major conference I’ve been to in the last few years, and sets up a small table in the back with his home mineral collection just for fun.  In practice this open-door policy is limited by the obscurity of the event itself; if you don’t move in research circles, you have to be something of a space exploration superfan to hear about it.  Still, as symbols go, you could do worse.

And now that we’re coming up on the day itself, the same kind of public-facing mindset is making me think about why I was persuaded to vote for Jezero Crater, what it means to explore there, and how I’d justify that choice to those of you that made the ongoing discovery of Mars possible in the first place.

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Tags:

#space #Mars #Perseverance #the power of science #the more you know #apocalypse cw

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