Wednesday, May 15, 2013

Alas, Kepler

The sad news broke this afternoon. By now it's been around the world a few times. The Kepler spacecraft has suffered serious equipment failure, over and above the problems it had last year. For now, and potentially forever, Kepler has lost its ability to point its telescopic apparatus with the precision required to track transiting planets.

“I wouldn’t call Kepler down and out yet,” said John Grunsfeld, a NASA official, but the planet-hunting community has registered extreme dejection anyhow. Geoff Marcy, the godfather of exoplanetary science, was inspired to circulate this variation on a lament by W.H. Auden (as reported in the LA Times):

Stop all the clocks, cut off the internet,
Prevent the dog from barking with a juicy bone,
Silence the pianos and with muffled drum
Bring out the coffin, let the mourners come.

Let jet airplanes circle at night overhead
Sky-writing over Cygnus: Kepler is dead.
Put crepe bows round the white necks of doves,
Let the traffic officers wear black cotton gloves.

Kepler was my North, my South, my East and West,
My working week, no weekend rest,
My noon, my midnight, my talks, my song;
I thought Kepler would last forever: I was wrong.

The stars are still wanted now; let's honor every one,
Pack up the moon and dismantle the sun,
Pour away the ocean and sweep up the woods;
For nothing will ever be this good.

Ah, but we still have so many blessings to count. Look at that poster at the top of this post -- look at all those candidate terrestrial planets! We had nothing like those data just four years ago. Or go to the Kepler Mission page and peruse the confirmed discoveries -- 132 planets and counting. If that isn't amazing, astounding, thrilling, weird, and wondrous, I'd like to know what is!

Kepler survived for the entire lifetime of its original mission, and it has already returned so much data that we can expect scores, if not hundreds, of new planets to emerge from the pipeline over the next few years. Many of them are bound to be cool-ish and Earth-ish, given four years of accumulated coverage. So I'm sad, I'm regretful, but I'm not really desolate.

After all, the Transiting Exoplanet Survey Satellite (TESS) is scheduled to launch in ONLY four years (or so) . . . and that new Star Trek movie is opening tonight . . . .

Postscript on May 27, 2013: On Thursday, May 16 (the day after I uploaded the preceding post), I went to the local university for a presentation by Jon Jenkins, a scientist and engineer who has been part of the Kepler Mission since before it was called Kepler. Jenkins gave an overview of the development of the telescopic apparatus, summarized mission highlights, and answered questions about Kepler’s future. Uppermost in the minds of just about everybody in the audience was whether the problem with the reaction wheel was fixable, and whether the flow of amazing new exoplanet data would continue as it has in the recent past.

Jenkins made it pretty clear that Kepler’s transit mission is finished. There seemed no hope that the spacecraft’s pointing ability could be restored, and nothing I’ve read in the days since then suggests otherwise. Nevertheless, Jenkins stressed that by any measure, Kepler has already proved to be a huge success, and its original mission has been completed more or less as planned. It’s only the extended mission – approved just last year – that had to be scuttled.

He also emphasized that large quantities of data already collected still await analysis. So in terms of new discoveries hitting the press, the next 10 or 12 months will probably be similar to the past 10 or 12. If I had to guess, I’d say we’ll be seeing more interesting new multiplanet systems, more subterrestrials, and more Earth-size planets in or near their systems’ habitable zones. Such planets are likely to orbit stars cooler than our Sun, since habitable planets of M, K, and even late G stars have periods shorter than 365 days, and thus are more easily detectable in the available Kepler datasets. 

Jenkins held out hope that the Kepler apparatus could be repurposed somehow to conduct observations that don’t require precise pointing, but I didn’t get a clear idea of what that alternative would look like.

Evidently we have a long wait until the next major onslaught of unprecedented marvels. CHEOPS, the CHaracterising ExOPlanets Satellite, won’t be launching until 2017. It involves a telescope in Earth orbit optimized to detect transiting planets of 6 Earth radii or less (i.e., telluric and gas dwarf planets) around nearby stars already known to host planets.

TESS, the Transiting Exoplanet Survey Satellite, is also scheduled for launch in 2017 – or maybe 2018, according to an online article I just saw. (As we know, launch dates have an unfortunate tendency to slip.) Unlike Kepler, which studied a limited region of space, TESS will conduct an all-sky survey focusing on planets in the Sun’s back yard, which I think is peachy. I only wish it would launch sooner.

WFIRST-2.4, another upcoming NASA mission, will use one of the two spare Hubble-quality telescopes that the U.S. Department of Defense recently decided it didn’t need. It’s slated to conduct three different programs relevant to exoplanetary science. According to a brand-new report by Spergel and colleagues, the first program is a microlensing survey of unparalleled scope and precision that will characterize “the demographics of exoplanets.” Another program will directly image planets around nearby stars. A third will image nearby debris disks at high resolution. All that sounds great, but there’s a catch – WFIRST-2.4 doesn’t have a launch date yet. Spergel and colleagues speak vaguely of work that will begin “early in the next decade.”

Meanwhile, I recommend Star Trek Into Darkness. It’s one of the better films in that franchise, and you’re hearing this from a non-Trekkie. (I myself belong to the fast-dwindling species of Barsoomiasts, who remain chained to the allegedly outmoded technology known as books.)

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