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Emily LakdawallaNovember 11, 2014

Report from Darmstadt: Philae status and early Rosetta results from DPS

I arrived in Darmstadt, Germany yesterday and headed straight to the European Space Operations Centre, the base for ESA's spacecraft operations and my workplace for the next week. I'm here, of course, to cover the exciting Philae landing on comet Churyumov-Gerasimenko; the seven-hour descent will take place during the day Wednesday here. There was a press briefing yesterday afternoon, but there is little news to report, which is the way it should be. Both spacecraft are ready. Philae is ready. The team is tired, but ready. Today, the team will begin working on shifts, 24 hours a day, until Philae's first science sequence is complete. There are currently no changes to the Philae timeline I posted last week. I'll do any updates and repost that article this evening, when the first significant event happens: the lander powers on at 18:05 UT. Less than 24 hours after that, if all goes well, Philae will be starting its surface science.

ESA Rosetta and Philae team at European Space Operations Centre, Nov. 10, 2014

Emily Lakdawalla

ESA Rosetta and Philae team at European Space Operations Centre, Nov. 10, 2014
From left to right: Matt Taylor, Rosetta project scientist; Stephan Ulamec, Philae project manager; and Andrea Accomazzo and Sylvain Lodiot, both Rosetta spacecraft operations managers

Mostly my visit to ESOC yesterday allowed me to greet old friends among both ESA staff and international space media. As the day wound down in Europe, the space media here in Darmstadt jealously watched the tweets coming in from a scientific session at the Division for Planetary Sciences meeting in Tucson, where the first results from Rosetta's work at comet Churyumov-Gerasimenko were being presented. We're not there and there is no webcast, so all we can do is be tantalized by the excited tweets coming from scientists at the meeting. I'd like it if there were at least a little bit of coverage of this at ESOC today, but I'm not too hopeful. So a distant second-best thing is to share some of these excited tweets with you, and provide context as needed. Here goes:

The first presentation was by Nicholas Thomas, on albedo and color variations on comet 67P as observed by OSIRIS. I've been dying to see more OSIRIS data -- only a handful of photos have been released, and none of them is in color. It's killing me that I didn't get to see the pictures that had a packed roomful of scientists repeatedly break into spontaneous applause today.

Currently @ESA_Rosetta's shape model of #67P is good to about 5 meters. Still disputing the contact binary hypothesis. #DPS14

— Alex Parker (@Alex_Parker) November 10, 2014

Thomas: 5 main surface morphologies on #67P: dust-covered brittle, exposed, large-scale depressions, smooth areas, consolidated. #DPS14

— Andy Rivkin (@asrivkin) November 10, 2014

Comet is weaksauce. Like, tensile strength of < 20 Pa weaksauce. #DPS14

— Alex Parker (@Alex_Parker) November 10, 2014

Thomas: icy boulders on CG being exposed after a collapse of materials. #DPS46

— Jason Cook (@AstroCook) November 10, 2014

Thomas: fractures 100s of m long in various parts of #67P. Thermal shock/"insulation weathering"? Evidence "chunks" lost-ejected? #DPS14

— Andy Rivkin (@asrivkin) November 10, 2014

Sparkly comet is sparkly. In high-res OSIRIS images, seeing specks of brighter materials (ices?). #DPS14

— Alex Parker (@Alex_Parker) November 10, 2014

Thomas: Ponded materials seen, like on Eros! Circular structures like on Tempel 2. "Mud volcanoes model" relevant? #DPS14

— Andy Rivkin (@asrivkin) November 10, 2014

Thomas: Resolving individual grains leaving the comet. ... Looks like a snow storm. #DPS46

— Jason Cook (@AstroCook) November 10, 2014

Starting #DPS14 on a high - oos and ahs from audience as Rosetta reveals amazing images of a new world. Spontaneous applause!

— Leigh Fletcher (@LeighFletcher) November 10, 2014

Thomas: Can trace dust jets all the way to the surface, see individual grains! In long exposures see grains curve from gas drag! #DPS14

— Andy Rivkin (@asrivkin) November 10, 2014

Room just burst into applause at a new picture of the #67P environs. The picture did not have the comet itself in it. Wow. Just. Wow. #DPS14

— Alex Parker (@Alex_Parker) November 10, 2014

Thomas calls #67P "dunes". Says consistent with saltation but equations used way outside usual bounds. #DPS14

— Andy Rivkin (@asrivkin) November 10, 2014

Nicolas Thomas: @ESA_Rosetta sees no evidence of surface changes yet #DPS14

— Morgan Rehnberg (@MorganRehnberg) November 10, 2014

Dunes made from saltating grains? Mud volcanoes? What is this, Mars?

Anyway. The next talk was by Ceric Leyrat, also representing the OSIRIS team. His work was evidently based upon color maps of the nucleus, which I really, really wish I could have seen. They sound amazing.

Leyrat: color maps made from 11 filters. bright/white near neck. Rust/red and gray over rest. Albedo 5.3+/-0.1% with 30% variation. #DPS46.

— Jason Cook (@AstroCook) November 10, 2014

Leyrat: bright neck is bluer and consistent with H2O ice. Emission near 770 nm near pits. Seeing ice patches on surface. #DPS14

— Jason Cook (@AstroCook) November 10, 2014

Leyrat on spectral slope of 67P/C-G: looks like a D-type asteroid (ed. note: not surprising, that's standard for comet nuclei) #DPS14

— Erin Ryan (@erinleeryan) November 10, 2014

Leyrat: color maps made from 11 filters. bright/white near neck. Rust/red and gray over rest. Albedo 5.3+/-0.1% with 30% variation. #DPS14

— Jason Cook (@AstroCook) November 10, 2014

It's interesting that Rosetta team members are asking the speakers (other Rosetta team members) about the findings they are presenting.

— Alex Parker (@Alex_Parker) November 10, 2014

Cedric Leyrat: @ESA_Rosetta sees very small grains on the surface of 67P #DPS14

— Morgan Rehnberg (@MorganRehnberg) November 10, 2014

RT @OSIRISREx: Out gassing is unlikely to be a force that caused landslides (if they exist) on comet #67p #DPS14

— Emily Lakdawalla (@elakdawalla) November 10, 2014

Next up were a couple of presentations from the MIRO instrument, including ones by Mark Hofstadter and by Seungwon Lee, which focused on the comet's outgassing activity:

Hofstadter: avg water production rate 1e25 in June to 6e25 in October. Avg gas expansion velocity increased from 400 to 700m/s #DPS14 #67P

— Andrew Steffl (@plasma_torus) November 10, 2014

.@ESA_Rosetta sees strong diurnal variation in vapor production. Probably from first 2 cm of surface #DPS14

— Morgan Rehnberg (@MorganRehnberg) November 10, 2014

Hofstadter MIRO sees "porous, dusty surface that is incredibly insulating"You only need to go down a mm or 2 to go down 50K in temp #DPS2014

— Andrew Steffl (@plasma_torus) November 10, 2014

Need only .1-1% of surface sublimation to produce observed results from @ESA_Rosetta #DPS14

— Morgan Rehnberg (@MorganRehnberg) November 10, 2014

Water production rate jumped x6 as #67P moved from 3.9 to 2.8AU, dayside bright neck is the most active region for dust/gas jets #DPS14

— Leigh Fletcher (@LeighFletcher) November 10, 2014

S. Lee: @ESA_Rosetta finds outgassing peaks around late afternoon on 67P #DPS14

— Morgan Rehnberg (@MorganRehnberg) November 10, 2014

S. Lee: @ESA_Rosetta finds outgassing rate varies by up to a factor of 20 #DPS14

— Morgan Rehnberg (@MorganRehnberg) November 10, 2014

At some point someone asked the question that's been burning in all our minds:

Best #DPS14 question: given the sublimation rate of 67P/C-G has anyone calculated the point at which the rubber ducky's head snaps off?

— Erin Ryan (@erinleeryan) November 10, 2014

No matter how things with Philae pan out, we can already call #67P a "joy of joys". Unclear if squeezing it will make noise, though. #DPS14

— Andy Rivkin (@asrivkin) November 10, 2014

In a more serious mode:

One of the big questions of #67P is whether the neck was created by a contact binary or increased local activity created the neck #DPS2014

— Andrew Steffl (@plasma_torus) November 10, 2014

Next up came several presentations by Alan Stern, Lori Feaga, and Paul Feldman on surface and coma results from Rosetta's ultraviolet imager, ALICE -- which has a sister instrument on New Horizons, by the way.

Stern: FUV reflectance is only 1% at 1800Å, but increases to 2% below 1200Å. #DPS2014

— Andrew Steffl (@plasma_torus) November 10, 2014

Stern: It's hard to imagine stuff this dark, in fact, we pay extra for coatings like that. #DPS2014

— Andrew Steffl (@plasma_torus) November 10, 2014

.@AlanStern: surface of 67P likely fluffy. Damps out much of the incoming light: only 1% reflective in UV #DPS14

— Morgan Rehnberg (@MorganRehnberg) November 10, 2014

Stern: at 2000 angstroms/ UV, albedo of 67P/G-G is 1 to 2% (blacker than the blackest black) but has a blue slope, no H2O match #dps14

— Erin Ryan (@erinleeryan) November 10, 2014

Stern: We don't see any sign of H20 ice on the surface. Formal fit is one part in 10^-4. Do get a pretty good fit w/ tholens. #DPS2014

— Andrew Steffl (@plasma_torus) November 10, 2014

Stern: UV spectra suggests 75% tholins, 25% carbon, << 1% H2O ice, blue color maybe due to UV solid state band? #dps14

— Erin Ryan (@erinleeryan) November 10, 2014

Feaga: spatially resolved FUV spectra of CG. Head more reflective over body. Neck is bluer. -60%/1000 A slope. #DPS14

— Jason Cook (@AstroCook) November 10, 2014

Feaga: The neck region of #67P has a larger FUV blue slope than other regions, but still no sign of exposed water ice on surface #DPS2014

— Andrew Steffl (@plasma_torus) November 10, 2014

Lori Feaga: geometry may play a role in brighter head of 67P in the UV #DPS14

— Morgan Rehnberg (@MorganRehnberg) November 10, 2014

Feldman: H and O coma emissions seen at #67P caused by electron impact. Electrons come from photoionization of H2O. Surprising! #DPS2014

— Andrew Steffl (@plasma_torus) November 10, 2014

Feldman: Atomic O, C, H, and CO #DPS14

— Jason Cook (@AstroCook) November 10, 2014

Finally, two talks from the VIRTIS team about the nucleus of the comet in infrared wavelenghts, given by Fabrizio Capaccioni and Pierre Drossart:

Fabrizio Capaccioni: @ESA_Rosetta observes an IR reflectance of ~6% on 67P #DPS14

— Morgan Rehnberg (@MorganRehnberg) November 10, 2014

Fabrizio Capaccioni: @ESA_Rosetta observes an IR reflectance of ~6% on 67P #DPS14

— Morgan Rehnberg (@MorganRehnberg) November 10, 2014

Fabrizio Capaccioni: @ESA_Rosetta finds maximum temperatures in 67P of ~220 K #DPS14

— Morgan Rehnberg (@MorganRehnberg) November 10, 2014

thing that is getting stressed over and over again in Rosetta talks at #dps14 : the neck of 67P/C-G is bluer than the head or body.

— Erin Ryan (@erinleeryan) November 10, 2014

Capaccioni on Rosetta VIRTIS results at #dps14: there’s broad 3ish um band, but it’s maybe not consistent w/ H2O (me note: umm, mixtures?)

— Erin Ryan (@erinleeryan) November 10, 2014

All in all, it sounds like an amazing data set, and I'm looking forward to writing up the science when I get a chance to hear and see it first-hand. In the meantime, though, I've got a comet landing to watch. Stay tuned -- I'll have more to report later today!

Read more: Rosetta and Philae, comets, mission status, comet Churyumov-Gerasimenko, explaining science

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Emily Lakdawalla

Senior Editor and Planetary Evangelist for The Planetary Society
Read more articles by Emily Lakdawalla

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