{"id":16410,"date":"2015-04-12T23:54:54","date_gmt":"2015-04-12T15:54:54","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/rosetta-keeps-its-distance-from-awakening-comet\/"},"modified":"2015-04-12T23:54:54","modified_gmt":"2015-04-12T15:54:54","slug":"rosetta-keeps-its-distance-from-awakening-comet","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/rosetta-keeps-its-distance-from-awakening-comet\/","title":{"rendered":"Rosetta keeps its distance from awakening comet"},"content":{"rendered":"
\"Rosetta's
Rosetta\u2019s navigation camera took images for this mosaic of comet 67P\/Churyumov-Gerasimenko on April 8. Credit: ESA\/Rosetta\/NAVCAM<\/figcaption><\/figure>\n

Mission controllers are rethinking a series of close-up comet flybys planned for Europe\u2019s Rosetta spacecraft after a haze of dust around the comet\u2019s central nucleus led to navigation errors during a close encounter in late March.<\/p>\n

Rosetta\u2019s computer put the spacecraft into safe mode in the aftermath of a March 28 flyby of comet 67P\/Churyumov-Gerasimenko. Star trackers aboard the solar-powered probe were unable to lock on to guide stars, confusing the craft\u2019s navigation system and causing Rosetta\u2019s communications antenna to drift off alignment with Earth.<\/p>\n

Ground teams blamed the glitch on dust particles around the comet\u2019s nucleus. The guidance system confused the flecks of dust for stars, rendering the star trackers unable to set a navigation fix.<\/p>\n

Rosetta is supposed to track the locations of bright stars to determine which way it is pointing in space.<\/p>\n

The spacecraft defaulted into safe mode, a standby configuration where Rosetta switches off its science instruments and halts non-essential functions to ensure the probe\u2019s survival.<\/p>\n

Rosetta\u2019s maneuvering capabilities were curtailed when the spacecraft was in safe mode, causing the orbiter to fly away from the comet on an escape trajectory, reaching a distance of about 400 kilometers (248 miles). A pair of thruster burns put Rosetta back on a course closer to the comet, and it arrived at a point 140 kilometers (87 miles) by April 8.<\/p>\n

But plans for further close-up encounters with the comet\u2019s irregular-shaped nucleus have been postponed for now.<\/p>\n

\u201cThis has ultimately meant a complete replanning of the upcoming flyby trajectories,\u201d said Sylvain Lodiot, Rosetta spacecraft operations manager, in a post on a European Space Agency website. \u201cWe\u2019re first moving to a terminator orbit at a distance of 140 kilometers and then we\u2019re targeting 100 kilometers (62 miles). Then we will adopt a similar strategy to when we first approached the comet in August last year. That is, we will fly \u2018pyramid\u2019 trajectories, starting at about 100 kilometers on April 11, and we\u2019ll monitor how the spacecraft reacts before moving closer.\u201d<\/p>\n

\"Artist's
Artist\u2019s concept of Rosetta\u2019s pyramid-shaped trajectory around the comet. Credit: ESA<\/figcaption><\/figure>\n

Rosetta will complete three pyramid-shaped laps around comet 67P\u2019s rocky core through the end of April, but officials are wary of sending the spacecraft closer to the comet. Ground teams want to monitor the growing cloud of dust and vapor around the comet before deciding the mission\u2019s long-term trajectory.<\/p>\n

The March 28 encounter took Rosetta about 14 kilometers (8.7 miles) from the comet\u2019s surface, following up on a 6-kilometer (3.7-mile) flyby in February.<\/p>\n

Before Rosetta ran into problems March 28, the mission plan called for the craft to conduct similar close approaches to the comet over the coming months, including a targeted flyby through one of the comet\u2019s jets launching water vapor and other materials into space.<\/p>\n

Scientists expect the comet to spit off more material as its orbit swings closer to the sun. Heat from the sun is making the hibernating comet come alive, triggering plumes and expanding the tiny world\u2019s coma, the fuzzy cloud often seen in telescopic views of comets.<\/p>\n

Comet 67P will be nearest to the sun Aug. 13, and experts predict the comet to reach maximum activity in September.<\/p>\n

\u201cWe\u2019re now assessing the impact of the new trajectory scheme on the planned science observations for the months ahead, including those which anticipated close flybys,\u201d said Matt Taylor, Rosetta\u2019s project scientist, in a statement on ESA\u2019s website. \u201cOur science operations team at ESAC is extremely busy working with the instrument teams to optimize science observations and associated spacecraft pointing for this new scheme. As we move forward, we will analyze what can be modified and improved in order to maximize science return within the capabilities of the spacecraft. We will be looking at examining all options to mitigate the issues we had and recover some of the science goals.\u201d<\/p>\n

Ground controllers expected they may have to adjust Rosetta\u2019s flight plan due to growing activity at the comet. Another concern with Rosetta\u2019s close flybys involves drag and impacts on the spacecraft\u2019s wide-spanning solar panels, but those issues have \u2014 so far \u2014 proven less serious than the star tracker miscue.<\/p>\n

Meanwhile, Rosetta was scheduled to begin another listening campaign Sunday to monitor for radio signals from the Philae lander dropped to the comet\u2019s nucleus in November. Scientists last heard from the landing craft two days after it touched down in November, but they hope Philae will recharge its batteries in the coming months as the probe receives more sunlight.<\/p>\n

\u201cThe communication unit on the orbiter will be turned on around the clock,\u201d said Stephan Ulamec, manager of the Philae lander team at DLR, the German space agency.<\/p>\n

\u201cMost likely, Philae will wake up in May or June, but we don\u2019t want to miss the moment if it should have enough energy and a sufficiently high operating temperature to wake up earlier,\u201d Ulamec said in a blog post on ESA\u2019s website.<\/p>\n

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

Rosetta\u2019s navigation camera took images for this mosaic of comet 67P\/Churyumov-Gerasimenko on April 8. Credit: ESA\/Rosetta\/NAVCAM Mission controllers are rethinking a series of close-up comet flybys planned for Europe\u2019s Rosetta spacecraft after a haze of dust around the comet\u2019s central nucleus led to navigation errors during a close encounter in late March. Rosetta\u2019s computer put […]<\/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":[3097,3098,3609,3373],"class_list":["post-16410","post","type-post","status-publish","format-standard","hentry","category-news","tag-comet","tag-comet-67p-churyumov-gerasimenko","tag-philae","tag-rosetta"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/16410"}],"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=16410"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/16410\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=16410"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=16410"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=16410"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}