"Long before it's in the papers"
January 27, 2015


Comet lander loses power but completes “primary” job

Nov. 15, 2014
Courtesy of ESA
and World Science staff

A probe sent to land on a com­et for the first time has lost pow­er but man­aged to com­plete its “pri­mary sci­ence mis­sion,” mis­sion sci­en­tists re­ported Sat­ur­day.

They added that the lan­der might re­a­wak­en when there is more light for its so­lar pan­els, pos­sibly around when the com­et ap­proaches the Sun. The clos­est ap­proach is next Au­gust. 

A view from the Philae lander, one of whose feet is visible as the white ob­ject at at low­er left. The im­age is a mo­saic of two ori­ginal im­ages. (© ESA/Ro­set­ta/Phi­lae/CI­VA)

As the sci­en­tists with the Eu­ro­pe­an Space Agen­cy mission tell it, the Phi­lae lan­der was on the com­et for 57 hours be­fore los­ing pow­er as a re­sult of its so­lar pan­els not get­ting enough light.

In­deed, sci­en­tists had nev­er con­sid­ered it a sure thing to beg­in with that such light would be avail­a­ble.

Ac­cord­ing­ly, only a pos­sible “ex­tended sci­ence mis­sion,” not the “pri­mary” mis­sion, was made con­tin­gent on that light and its re­sulting pow­er. The “pri­mary” mis­sion de­pended on a sep­a­rate bat­tery.

As it turned out, mis­sion sci­en­tists said, the lack of light seems to be a re­sult of the lan­der’s un­ex­pectedly bounc­ing twice off Com­et 67P/Churyu­mov-Ger­asi­men­ko af­ter an in­i­tial touch­down. The bounces left the probe in an un­in­tend­ed spot, in the shad­ow of a cliff, and are be­lieved to be the re­sult of one or two mal­func­tions, in­clud­ing the fail­ure of har­poons meant to tie the lan­der down to its tar­geted land­ing site.

Phi­lae re­mained in con­tact and able to de­liv­er da­ta and pic­tures un­til 1:36 a.m. Cen­tral Eu­ro­pe­an Time Sat­ur­day, mis­sion sci­en­tists said. A small ad­just­ment in its po­si­tion failed to pre­vent the sub­se­quent pow­er loss, but sci­en­tists be­lieve the ad­just­ment may boost the chances of a lat­er re­a­wak­ening.

The agen­cy had sent a space­craft called Ro­set­ta to or­bit the com­et. Ro­set­ta in turn de­liv­ered Phi­lae there. Ro­set­ta it­self con­tin­ues to study the com­et, mis­sion sci­en­tists said.

Agen­cy of­fi­cials and sci­en­tists put a pos­i­tive face on the over­all situa­t­ion. Fred Jan­sen, ESA’s Ro­set­ta mis­sion man­ag­er, pre­dicted “many more months of ex­cit­ing Ro­set­ta sci­ence and pos­sibly a re­turn of Phi­lae from hi­berna­t­ion at some point,” not­ing that it has been a “roller­coaster week.”

“It has been a huge suc­cess, the whole team is de­light­ed,” added Stephan Ulamec, lan­der man­ag­er at the DLR Ger­man Aer­o­space Agen­cy, who mon­i­tored Phi­lae’s prog­ress from ESA’s Space Opera­t­ions Cen­tre in Darm­stadt, Ger­many, this week.

De­spite sna­fus, all the sci­en­tif­ic in­stru­ments worked “and now it’s time to see what we’ve got” from the da­ta re­turned so far, he added.

The lan­der’s ex­act loca­t­ion on the com­et re­mains only roughly known. The search for that con­tin­ues, with high-resolution im­ages from Ro­set­ta space­craft, which is or­biting the com­et, un­der close scru­ti­ny. Mean­while, the lan­der has re­turned un­prec­e­dent­ed im­ages of its sur­round­ings.

While de­scent im­ages show that the sur­face of the com­et is cov­ered by dust and de­bris rang­ing up to a me­ter (yard) in size, pan­o­ram­ic im­ages showed lay­ered walls of harder-looking ma­te­ri­al. The sci­ence teams are now stu­dying their da­ta to see if they have sam­pled any of this ma­te­ri­al with Phi­lae’s drill.

Da­ta col­lect­ed by the or­biter is in­tend­ed to al­low sci­en­tists to watch the short- and long-term changes that take place on the com­et, help­ing to an­swer some of the big­gest and most im­por­tant ques­tions re­gard­ing the his­to­ry of our So­lar Sys­tem. How did it form and evolve? How do com­ets work? What role did com­ets play in the ev­o­lu­tion of the plan­ets, of wa­ter on the Earth, and per­haps even of life on our home world?

“The da­ta col­lect­ed by Phi­lae and Ro­set­ta is set to make this mis­sion a game-changer in com­etary sci­ence,” said Matt Tay­lor, ESA’s Ro­set­ta proj­ect sci­ent­ist.

* * *

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A European Space Agency probe sent to land on a comet for the first time has lost power but managed to complete its “primary science mission,” mission scientists reported Saturday. They added that the lander might reawaken when there is more light for its solar panels, possibly around when the comet approaches the Sun. The closest approach is next August. As mission scientists tell it, the Philae lander was on the comet for 57 hours before losing power as a result of its solar panels not getting enough light. Indeed, scientists had never considered it a sure thing to begin with that such light would be available. Accordingly, only a possible “extended science mission,” not the “primary” mission, was made contingent on that light and its resulting power. The “primary” mission depended on a separate battery. As it turned out, mission scientists said, the lack of light seems to be a result of the lander’s unexpectedly bouncing twice off Comet 67P/Churyumov-Gerasimenko after an initial touchdown. The bounces left the probe in an unintended spot, in the shadow of a cliff, and are believed to be the result of one or two malfunctions, including the failure of harpoons meant to tie the lander down to its targeted landing site. Philae remained in contact and able to deliver data and pictures until 1:36 a.m. Central European Time Saturday, mission scientists said. A small adjustment in its position failed to prevent the subsequent power loss, but scientists believe the adjustment may boost the chances of a later reawakening. The agency had sent a spacecraft called Rosetta to orbit the comet. Rosetta in turn delivered Philae to the comet. Rosetta itself continues to study the comet, mission scientists said. Agency officials and scientists put a positive face on the overall situation. Fred Jansen, ESA’s Rosetta mission manager, predicted “many more months of exciting Rosetta science and possibly a return of Philae from hibernation at some point,” noting that it has been a “rollercoaster week.” “It has been a huge success, the whole team is delighted,” added Stephan Ulamec, lander manager at the DLR German Aerospace Agency, who monitored Philae’s progress from ESA’s Space Operations Centre in Darmstadt, Germany, this week. Despite snafus, all the scientific instruments worked “and now it’s time to see what we’ve got” from the data returned so far, he added. The lander’s exact location on the comet remains only roughly known. The search for that continues, with high-resolution images from Rosetta spacecraft, which is orbiting the comet, under close scrutiny. Meanwhile, the lander has returned unprecedented images of its surroundings. While descent images show that the surface of the comet is covered by dust and debris ranging up to a meter (yard) in size, panoramic images showed layered walls of harder-looking material. The science teams are now studying their data to see if they have sampled any of this material with Philae’s drill. Data collected by the orbiter is intended to allow scientists to watch the short- and long-term changes that take place on the comet, helping to answer some of the biggest and most important questions regarding the history of our Solar System. How did it form and evolve? How do comets work? What role did comets play in the evolution of the planets, of water on the Earth, and perhaps even of life on our home world? “The data collected by Philae and Rosetta is set to make this mission a game-changer in cometary science,” said Matt Taylor, ESA’s Rosetta project scientist.