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Lander touches down on comet

Nov. 12, 2014
Courtesy of ESA
and World Science staff

The Eu­ro­pe­an Space Agen­cy’s Ro­set­ta mis­sion has softly land­ed a probe up­on a com­et, the first time in his­to­ry such a feat has been achieved, proj­ect sci­en­tists said Wednes­day.

Af­ter a tense wait amid a seven-hour drop, a sig­nal con­firm­ing the touch­down on Com­et 67P/Chur­yu­mov-Ge­ra­si­men­ko hit Earth at 5:03 p.m. Cen­tral Eu­ro­pe­an time.

comet 67P/CG imaged by the Philae lander during descent from of about  3 km (2 miles) from the surface. The landing site is imaged with a resolution of about 3 meters (yards) per pixel. (© ESA/Rosetta/Philae/ROLIS/DLR)


The mis­sion was “the first to ren­dez­vous with and or­bit a com­et,” and is now al­so “the first to de­liv­er a lan­der to a com­et’s sur­face,” said agen­cy Di­rec­tor Gen­er­al Jean-Jacques Dor­dain. 

“We are open­ing a door to the or­i­gin of plan­et Earth and fos­ter­ing a bet­ter un­der­stand­ing of our fu­ture.”

“Af­ter more than 10 years trav­el­ing through space, we’re now mak­ing the best ev­er sci­en­tif­ic anal­y­sis of one of the old­est rem­nants of our So­lar Sys­tem,” added Al­va­ro Giménez, ESA’s Di­rec­tor of Sci­ence and Robotic Ex­plora­t­ion.

The land­ing oc­curred de­spite a prob­lem that was de­tected with one of the thrust­ers dur­ing a fi­nal “health check” of the lan­der, of­fi­cials said. It re­mained un­clear wheth­er the thrust­er ac­tu­ally pe­r­formed, and re­search­ers said they’re in­ves­ti­gat­ing this.

“We are ex­tremely re­lieved to be safely on the sur­face,” said Stephan Ulamec, Phi­lae Lan­der Man­ag­er at DLR, Ger­many’s na­t­ional aer­o­naut­ics and space re­search cen­ter. “In the next hours we’ll learn ex­actly where and how we’ve land­ed, and we’ll start get­ting as much sci­ence as we can.” 

Ro­set­ta trav­eled 6.4 bil­lion kilo­me­ters (4 bil­lion miles) through the So­lar Sys­tem be­fore ar­riv­ing in the com­et’s vicin­ity on Aug. 6. The land­ing site, named Ag­ilkia and lo­cat­ed on the head of the bi­zarre dumbbell-shaped ob­ject, was pick­ed six weeks lat­er based on close-up im­ages and da­ta. These re­vealed the com­et as a world lit­tered with boul­ders, tow­er­ing cliffs and daunt­ing precipices and pits, with jets of gas and dust stream­ing out.

Fol­low­ing a pe­ri­od spent at 10 km (6 miles) for fur­ther close-up study of the land­ing site, Ro­set­ta moved on­to a more dis­tant tra­jec­to­ry to pre­pare for de­ploy­ment. Five crit­i­cal go/no-go de­ci­sions were made last night and early this morn­ing, sci­en­tists said, con­firm­ing dif­fer­ent stages of read­i­ness ahead of separa­t­ion, along with a fi­nal pre-separa­t­ion ma­neu­ver by the or­biter.

Dur­ing the seven-hour de­scent, made with­out pro­pul­sion or guid­ance, Phi­lae took im­ages and recorded in­forma­t­ion. 

“One of the great­est un­cer­tain­ties… was the po­si­tion of Ro­set­ta at the time of de­ploy­ment, which was in­flu­enced by the ac­ti­vity of the com­et at that spe­cif­ic mo­ment, and which in turn could al­so have af­fect­ed the lan­der’s de­scent tra­jec­to­ry,” said Syl­vain Lo­diot, ESA Ro­set­ta Space­craft Ope­ra­t­ions Man­ag­er. “Fur­ther­more, we’re pe­r­form­ing these ope­ra­t­ions in an en­vi­ron­ment that we’ve only just started learn­ing about, 510 mil­lion km (320 mil­lion miles) from Earth.”

Touch­down was planned to take place at around 1 me­ter (yard) per sec­ond, with the three-legged land­ing gear ab­sorb­ing the im­pact to pre­vent re­bound, and an ice screw in each foot driv­ing in­to the sur­face.

Over the next 2½ days, the lan­der is to con­duct its main sci­ence mis­sion, as­sum­ing its main bat­tery re­mains healthy. An ex­tend­ed sci­ence phase us­ing the re­charge­a­ble sec­ondary bat­tery may be pos­si­ble through about March, sci­en­tists said, bar­ring prob­lems with light­ing and dust.

High­lights from the pri­ma­ry phase are to in­clude a full pan­o­ram­ic view of the land­ing site, in­clud­ing a sec­tion in 3D, high-resolution im­ages of the sur­face right un­derneath the lan­der, on-the-spot anal­y­sis of the make­up of com­et sur­face ma­te­ri­als, and a drill that will take sam­ples for anal­y­sis by an on­board lab­o­r­a­to­ry.

“Ro­set­ta is try­ing to an­swer the very big ques­tions about the his­to­ry of our So­lar Sys­tem. What were the con­di­tions like at its in­fan­cy and how did it evolve? What role did com­ets play in this ev­o­lu­tion? How do com­ets work?” said Matt Tay­lor, ESA Ro­set­ta proj­ect sci­ent­ist.


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The European Space Agency’s Rosetta mission has softly landed a probe upon a comet, the first time in history such a feat has been achieved, project scientists said Wednesday. After a tense wait amid a seven-hour descent, a signal confirming the touchdown on Comet 67P/Churyumov-Gerasimenko reached Earth at 5:03 p.m. Central European time. The mission was “the first to rendezvous with and orbit a comet,” and is now also “the first to deliver a lander to a comet’s surface,” said agency Director General Jean-Jacques Dordain. “With Rosetta we are opening a door to the origin of planet Earth and fostering a better understanding of our future.” “After more than 10 years traveling through space, we’re now making the best ever scientific analysis of one of the oldest remnants of our Solar System,” added Alvaro Giménez, ESA’s Director of Science and Robotic Exploration. The landing occurred despite a problem that was detected with one of the thrusters during a final “health check” of the lander, officials said. It remained unclear whether the thruster actually performed, and researchers said they’re investigating this. “We are extremely relieved to be safely on the surface,” said Stephan Ulamec, Philae Lander Manager at DLR, Germany’s national aeronautics and space research center. “In the next hours we’ll learn exactly where and how we’ve landed, and we’ll start getting as much science as we can.” Rosetta traveled 6.4 billion kilometers (4 billion miles) through the Solar System before arriving in the comet’s vicinity on Aug. 6. The landing site, named Agilkia and located on the head of the bizarre dumbbell-shaped object, was picked six weeks later based on close-up images and data. These revealed the comet as a world littered with boulders, towering cliffs and daunting precipices and pits, with jets of gas and dust streaming out. Following a period spent at 10 km (6 miles) for further close-up study of the landing site, Rosetta moved onto a more distant trajectory to prepare for deployment. Five critical go/no-go decisions were made last night and early this morning, scientists said, confirming different stages of readiness ahead of separation, along with a final pre-separation maneuver by the orbiter. During the seven-hour descent, made without propulsion or guidance, Philae took images and recorded information. “One of the greatest uncertainties… was the position of Rosetta at the time of deployment, which was influenced by the activity of the comet at that specific moment, and which in turn could also have affected the lander’s descent trajectory,” said Sylvain Lodiot, ESA Rosetta Spacecraft Operations Manager. “Furthermore, we’re performing these operations in an environment that we’ve only just started learning about, 510 million km (320 million miles) from Earth.” Touchdown was planned to take place at around 1 meter (yard) per second, with the three-legged landing gear absorbing the impact to prevent rebound, and an ice screw in each foot driving into the surface. Over the next 2½ days, the lander is to conduct its main science mission, assuming its main battery remains healthy. An extended science phase using the rechargeable secondary battery may be possible through about March, scientists said, barring problems with illumination and dust. Highlights from the primary phase are to include a full panoramic view of the landing site, including a section in 3D, high-resolution images of the surface right underneath the lander, on-the-spot analysis of the makeup of comet surface materials, and a drill that will take samples for analysis by an onboard laboratory. “Rosetta is trying to answer the very big questions about the history of our Solar System. What were the conditions like at its infancy and how did it evolve? What role did comets play in this evolution? How do comets work?” said Matt Taylor, ESA Rosetta project scientist.