{"id":16262,"date":"2015-06-15T20:09:28","date_gmt":"2015-06-15T12:09:28","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/engineers-seek-to-stabilize-radio-link-with-comet-lander\/"},"modified":"2015-06-15T20:09:28","modified_gmt":"2015-06-15T12:09:28","slug":"engineers-seek-to-stabilize-radio-link-with-comet-lander","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/engineers-seek-to-stabilize-radio-link-with-comet-lander\/","title":{"rendered":"Engineers seek to stabilize radio link with comet lander"},"content":{"rendered":"
\"Rosetta's
Rosetta\u2019s navigation camera captured this view of comet 67P\/Churyumov-Gerasimenko awakened by the sun June 5. Credit: ESA\/Rosetta\/NavCam<\/figcaption><\/figure>\n

Emboldened by renewed contact with Europe\u2019s comet lander, engineers are repositioning the mission\u2019s Rosetta mothership this week to establish a reliable a communications link with the dishwasher-sized Philae landing craft, a prerequisite for resuming a science campaign abbreviated by a power shortfall last year.<\/p>\n

The Rosetta spacecraft flying near comet 67P\/Churyumov-Gerasimenko picked up radio signals from Philae twice Saturday and Sunday, officials said Monday.<\/p>\n

Mission managers said both contacts were brief, but telemetry relayed to Earth through Rosetta indicated Philae was in fine shape after 211 days of silence lodged against a cliff somewhere on the comet\u2019s craggy nucleus.<\/p>\n

Temperatures on the lander have risen to minus 5 degrees Celsius (23 degrees Fahrenheit) \u2014 a favorable level \u2014 and the solar-powered probe reaches a peak power level of 24 watts when it receives maximum sunlight, according to the European Space Agency.<\/p>\n

European space officials hailed Philae\u2019s comeback in a press briefing Monday at the Paris Air Show.<\/p>\n

\u201cWe know now that we can get in touch with Philae,\u201d said Jean-Jacques Dordain, ESA\u2019s director general. \u201cIt will be getting warmer and warmer on the surface of the comet because, until the 13th of August, the comet will get closer and closer to the sun, so we should have more and more opportunities to get in touch with Philae.\u201d<\/p>\n

Johann Dietrich-Woerner, chairman of the German space agency DLR, said ground controllers plan to ease into limited science operations with Philae as soon as a reliable link is established with the lander through Rosetta.<\/p>\n

\u201cWe now have (nearly) three hours per day of sunshine on the Philae lander,\u201d said Woerner, who will assume the top post at ESA from Dordain on July 1. \u201cWe will change the orbit of Rosetta in order to get a better connection, and we will start then with all the scientific work with the so-called non-mechanical instruments, meaning not the drilling.\u201d<\/p>\n

\"Artist's
Artist\u2019s concept of the Philae comet lander. Credit: DLR<\/figcaption><\/figure>\n

Philae shut itself down in November about 60 hours after coming to a stop on the comet\u2019s nucleus. A cliff face blocked most sunlight at Philae\u2019s final resting place, and the probe\u2019s body-mounted solar panels received less than 90 minutes of illumination during each 12-hour rotation of the comet.<\/p>\n

Data received from Philae show it now receives approximately 135 minutes each \u201ccomet day,\u201d double the illumination the lander got in November.<\/p>\n

\u201cWe are still examining the housekeeping information at the Lander Control Center in the DLR German Aerospace Center\u2019s establishment in Cologne, but we can already tell that all lander subsystems are working nominally, with no apparent degradation after more than half a year hiding out on the comet\u2019s frozen surface,\u201d said Stephan Ulamec, Philae\u2019s project manager at DLR.<\/p>\n

\u201cWhile the information we have is very preliminary, it appears that the lander is in as good a condition as we could have hoped,\u201d Ulamec said in a statement.<\/p>\n

The first of Philae\u2019s two radio contacts with Rosetta occurred late Saturday, when ground controllers received more than 300 telemetry packets \u2014 about 663 kilobits of data \u2014 that were stored aboard the lander\u2019s computer for up to several weeks.<\/p>\n

Saturday\u2019s 85-second linkup was followed Sunday by a second connection lasting just a few seconds, according to ESA.<\/p>\n

But Sunday\u2019s contact gave engineers a glimpse into Philae\u2019s current status.<\/p>\n

\u201cIt is clear that we have had two contacts, and the last one was actually very short but it was real-time,\u201d said Alvaro Gimenez, ESA\u2019s director of science and robotic exploration. \u201cThe first one was only, so to speak, old data that was stored and transmitted. We see the system is improving. It\u2019s getting the right temperature, and it\u2019s going to work.\u201d<\/p>\n

Next up for Rosetta\u2019s ground team based in Darmstadt, Germany, is a maneuver to alter the mothership\u2019s path around the comet.<\/p>\n

\"The
The Rosetta team celebrates Philae\u2019s landing on Nov. 12, 2014. Credit: ESA\/J. Mai<\/figcaption><\/figure>\n

Rosetta has kept its distance from the nucleus since a close flyby March 28 put the spacecraft into safe mode after a cloud of comet dust confused the orbiter\u2019s pointing system and caused its antenna to temporarily drift out of alignment with Earth.<\/p>\n

Barreling through space 304 million kilometers (188 million miles) from Earth, the comet is zooming toward the sun, and rising temperatures have activated jets of vapor and dust around the nucleus, complicating the task of navigating Rosetta.<\/p>\n

\u201cWe are at a distance because it\u2019s very dangerous to fly nearby,\u201d Gimenez told reporters Monday.<\/p>\n

Rosetta will change course at 2325 GMT (7:25 p.m. EDT) Tuesday to move from a distance of 235 kilometers (146 miles) to a range of 180 kilometers (112 miles), according to ESA.<\/p>\n

\u201cWe had already planned a slight reduction of distance to the nucleus,\u201d Andrea Accomazzo, ESA\u2019s Rosetta flight director, wrote in an email to Spaceflight Now. \u201cThis, of course, plays in favor of contacts with the lander. On top of this, we will now redirect Rosetta to the portion of the sky where it was last Saturday when we had contact with Philae. If we had let Rosetta go on its planned trajectory, we would have several days without contact possibility.\u201d<\/p>\n

The control team planned to upload commands to Rosetta on Monday for Tuesday\u2019s minor rocket burn to nudge the orbiter back toward the comet.<\/p>\n

Rosetta should be in a good position to receive signals from Philae by Friday. Once Rosetta makes reliable contact with the lander, scientists can send commands for Philae to resume science operations, officials said.<\/p>\n

\u201cWe are trying now to start working with the less power-consuming instruments, so we can make science with those instruments that don\u2019t require mechanical power like drills or moving Philae or rotating Philae,\u201d Gimenez said. \u201cWe will do that when we recharge the secondary battery.\u201d<\/p>\n

Science experiments could begin in less than a week, Gimenez said.<\/p>\n

Rosetta continued its exploration of comet 67P after Philae entered hibernation, executing a series of close-up flybys earlier this year. Rosetta is expected to stay near the comet until some time next year, when it will likely be guided on its own descent to the nucleus.<\/p>\n

\"Revised_lander_search_area_node_full_image_2\"
Analyzing radio signals transmitted between Philae and Rosetta during the lander\u2019s operation in November, ground teams say they have narrowed Philae\u2019s location to an ellipse 16 meters (52 feet) wide and 160 meters (525 feet) long. Ellipse: ESA\/Rosetta\/Philae\/CONSERT; Image: ESA\/Rosetta\/MPS for OSIRIS Team MPS\/UPD\/LAM\/IAA\/SSO\/INTA\/UPM\/DASP\/IDA<\/figcaption><\/figure>\n

\u201cMost of the scientific data are coming from Rosetta itself, meaning that on a continuous basis we get scientific data with Rosetta,\u201d Dordain said. \u201cBut it\u2019s very good to have contact with Philae because we should also be able to receive information from the surface of the comet.\u201d<\/p>\n

Echoing earlier comments from Philae\u2019s science team, Gimenez said the lander\u2019s tumultuous touchdown \u2014 in which its anchoring harpoons, braking rocket and ice screws all failed \u2014 allowed the probe to settle in a location with enough shade to stay cool as the comet speeds toward its closest encounter with the sun in August.<\/p>\n

Philae \u2014 the first probe to ever attempt landing on a comet \u2014 aimed for touchdown on a relatively flat sunlit region of comet 67P, a site selected by ESA for safety and to ensure the lander could recharge its batteries.<\/p>\n

But the craft bounced off and ended up on a different part of the comet, and the same sun-blocking cliff that prematurely halted Philae\u2019s mission in November should keep the probe from overheating as it approaches the sun. Scientists are still trying to pinpoint Philae\u2019s exact location with high-resolution images from Rosetta and analysis of radio waves from the lander.<\/p>\n

If Philae\u2019s descent went perfectly, scientists expected the lander to stop working in March due to high temperatures.<\/p>\n

\u201cIt was very fortunate that we landed where we landed and not in the other place because we could hibernate and then not be overheated when we were close to the sun,\u201d Gimenez said. \u201cWe\u2019ll be able to measure, for the first time ever, on a comet close to the sun when we are at perihelion. Otherwise, in the original plan, that would have not been possible.\u201d<\/p>\n

Gimenez chalked up the unexpected landing outcome as \u201cgood luck.\u201d<\/p>\n

Email the author.<\/i><\/b><\/p>\n

Follow Stephen Clark on Twitter: @StephenClark1.<\/strong><\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

Rosetta\u2019s navigation camera captured this view of comet 67P\/Churyumov-Gerasimenko awakened by the sun June 5. Credit: ESA\/Rosetta\/NavCam Emboldened by renewed contact with Europe\u2019s comet lander, engineers are repositioning the mission\u2019s Rosetta mothership this week to establish a reliable a communications link with the dishwasher-sized Philae landing craft, a prerequisite for resuming a science campaign abbreviated […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[3097,3098,3573,831,4022,3609,3373],"class_list":["post-16262","post","type-post","status-publish","format-standard","hentry","category-news","tag-comet","tag-comet-67p-churyumov-gerasimenko","tag-comet-landing","tag-european-space-agency","tag-paris-air-show","tag-philae","tag-rosetta"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/16262"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=16262"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/16262\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=16262"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=16262"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=16262"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}