{"id":4700,"date":"2015-06-16T12:22:11","date_gmt":"2015-06-16T12:22:11","guid":{"rendered":"http:\/\/revoscience.com\/en\/?p=4700"},"modified":"2015-06-16T12:22:11","modified_gmt":"2015-06-16T12:22:11","slug":"philae-wake-up-triggers-intense-planning","status":"publish","type":"post","link":"https:\/\/www.revoscience.com\/en\/philae-wake-up-triggers-intense-planning\/","title":{"rendered":"Philae wake-up triggers intense planning"},"content":{"rendered":"
\n
\"Comet<\/a>
Comet on 13 June 2015 \u2013 NavCam<\/figcaption><\/figure>\n

The receipt of signals from Rosetta\u2019s Philae lander on 13 June after 211 days of hibernation marked the start of intense activity. In coordination with its mission partners, ESA teams are working to juggle Rosetta\u2019s flight plan to help with renewed lander science investigations.<\/p>\n

Philae has woken up after seven months in hibernation on Comet 67P\/Churyumov\u2013Gerasimenko. Hidden by shadows, Philae shut down on 15 November 2014 at 00:36 GMT after completing its main science operations sequence on the comet when the primary battery expired as expected after about 60 hours.<\/p>\n

Since March 2015, when Philae\u2019s environmental conditions started to improve with higher surface temperatures and better illumination, the orbiter\u2019s receiver had been turned on periodically to listen for signals from the lander when the orbital geometry was thought to be optimum.<\/p>\n

On the evening of 13 June, a weak but solid radio link between Rosetta and the lander was finally established for 85 seconds. More than 300 \u2018packets\u2019 \u2013 663 kbits \u2013 of lander housekeeping telemetry were received. This information had been stored on board at an as-yet-to-be determined time in the past, as much as several days to a few weeks, so does not necessarily reflect the lander\u2019s current status.<\/p>\n

Rosetta then relayed the signal to ESA\u2019s European Space Operations Centre, ESOC, in Darmstadt, Germany, at 20:28 GMT.<\/p>\n<\/div>\n

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Lander subsystems working nominally<\/h3>\n
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\u201cWe are still examining the housekeeping information at the Lander Control Centre 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 says DLR’s Stephan Ulamec, Philae Lander Project Manager.<\/div>\n<\/div>\n<\/div>\n

A second, smaller burst of lander data was received on Sunday, 14 June, at about 21:26 GMT, lasting just a few seconds. These data were confirmed to give the current status, showing the lander\u2019s internal temperature had already risen to \u20135\u00baC.<\/p>\n

Philae\u2019s memory has stored over 8000 packets of additional status data, but it is unclear from when in recent days they were recorded.<\/p>\n<\/div>\n

\n

Here comes the Sun<\/h3>\n

Engineers at the Lander Control Centre have determined that Philae is already being exposed to sufficient sunlight to heat it to an acceptable operating temperature and to generate electricity.<\/p>\n

\u201cPower levels increase during the local \u2018comet day\u2019 \u2013 the part of the about-12 hour comet rotation when Philae is in sunlight \u2013 from 13 W at comet sunrise to above 24 W,\u201d notes ESA\u2019s Patrick Martin, Rosetta Mission Manager. \u201cIt needs at least 19 W to switch on the transmitter.\u201d<\/p>\n

The telemetry downloaded covered the lander\u2019s status for a full night\u2013day cycle of the comet, which is helping ground teams to understand how the Sun is shining on the lander. The solar panels appear to be receiving power for over 135 minutes in each illumination period.<\/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 says Dr Ulamec.<\/p>\n<\/div>\n

\u00a0The task at hand<\/strong><\/div>\n
\n
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The main task now for all the mission partners \u2013 ESA for Rosetta operations and DLR and France\u2019s CNES space agency for lander operations and science, respectively \u2013 is to determine how to optimise Rosetta’s orbit so as to facilitate contact and enable new science investigations.<\/p>\n<\/div>\n

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It is believed that there is sufficient power now being generated to allow some science measurements during the time Philae is illuminated, with initial activities focusing on low-power measurements. This first phase would also likely include measurements that did not previously generate science in November.<\/div>\n<\/div>\n

However, the mission teams first must establish a more robust link between Rosetta and Philae before uploading the first batch of science operations commands.<\/p>\n

The quality of the communication link is also possibly related to the trajectory Rosetta is flying and the orientation it adopts.<\/p>\n<\/div>\n

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Optimising an orbit 305 million km away<\/h3>\n

Currently, Rosetta experiences two possible communication slots per 24 hours \u2013 once per 12-hour comet rotation.<\/p>\n<\/div>\n

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Until 23:35 GMT on Tuesday, 16 June, Rosetta will be flying an orbit set by already-uploaded commands on the terminator \u2013 the plane between comet day and night \u2013 moving out from about 200 km to 235 km altitude.<\/div>\n<\/div>\n<\/div>\n

This orbit is not optimised for lander communication, so longer periods of contact may not be possible until the trajectory has been changed.<\/p>\n<\/div>\n

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\u201cWith work done by the flight dynamics and operations team at ESOC and based on intense planning being conducted with the mission partners today, a new orbit will be devised that ensures optimum lander communications beginning with the next command upload later tonight,\u201d says Paolo Ferri, ESA\u2019s Head of Mission Operations.<\/p>\n

This new orbit will include an already-planned reduction of distance from the nucleus, down to 180 km versus 200 km, and \u2018nadir pointing\u2019 \u2013 continuously pointing Rosetta\u2019s communications unit at the comet. In the coming days, the orbiter may also be moved closer to the comet, without compromising the safety of the spacecraft, to help communications.<\/p>\n

The new orbit will be flown by Rosetta starting after 23:25 GMT on 16 June until 19 June, aiming to enable more and longer contacts with Philae, especially towards the end of this period.<\/p>\n<\/div>\n

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Ready to react quickly<\/h3>\n

Establishing a regular and predictable pattern of contacts is a prerequisite for performing a complete assessment of the lander\u2019s status and for planning science operations.<\/p>\n

\u201cIf we manage to achieve and maintain a predictable contact pattern,\u201d continues Paolo Ferri, \u201cthe lander teams can devise a strategy for a new sequence of scientific operations.\u201d<\/p>\n

\u201cRegardless, we will stay very flexible and be ready to react quickly. It\u2019s clear this incredible mission continues to stimulate and challenge us, developing in ways we could never have predicted.\u201d<\/p>\n<\/div>\n

\n

As a bonus, any operation of Philae\u2019s instruments up to or through perihelion on 13 August \u2013 the comet\u2019s closest point to the Sun along its orbit \u2013 will allow in-situ study of a comet during its peak activity.<\/p>\n

Had Philae landed at the planned site, at\u00a0Agilkia<\/a>\u00a0in November 2014, its mission would likely have ended in March because of the higher temperatures of that location as solar illumination increased.<\/p>\n

Philae was contributed by a consortium led by DLR, the Max Planck Institute for Solar System Research (MPS), CNES and Italy\u2019s ASI space agency. It made the first-ever soft landing on a comet on 12 November 2014.<\/p>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

The receipt of signals from Rosetta\u2019s Philae lander on 13 June after 211 days of hibernation marked the start of intense activity. In coordination with its mission partners, ESA teams are working to juggle Rosetta\u2019s flight plan to help with renewed lander science investigations. Philae has woken up after seven months in hibernation on Comet […]<\/p>\n","protected":false},"author":2,"featured_media":4701,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[20],"tags":[],"class_list":["post-4700","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-space-news"],"featured_image_urls":{"full":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/06\/Comet_on_13_June_2015_NavCam_medium.jpg",305,172,false],"thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/06\/Comet_on_13_June_2015_NavCam_medium-150x150.jpg",150,150,true],"medium":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/06\/Comet_on_13_June_2015_NavCam_medium-300x169.jpg",300,169,true],"medium_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/06\/Comet_on_13_June_2015_NavCam_medium.jpg",305,172,false],"large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/06\/Comet_on_13_June_2015_NavCam_medium.jpg",305,172,false],"1536x1536":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/06\/Comet_on_13_June_2015_NavCam_medium.jpg",305,172,false],"2048x2048":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/06\/Comet_on_13_June_2015_NavCam_medium.jpg",305,172,false],"ultp_layout_landscape_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/06\/Comet_on_13_June_2015_NavCam_medium.jpg",305,172,false],"ultp_layout_landscape":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/06\/Comet_on_13_June_2015_NavCam_medium.jpg",305,172,false],"ultp_layout_portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/06\/Comet_on_13_June_2015_NavCam_medium.jpg",305,172,false],"ultp_layout_square":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/06\/Comet_on_13_June_2015_NavCam_medium.jpg",305,172,false],"newspaper-x-single-post":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/06\/Comet_on_13_June_2015_NavCam_medium.jpg",305,172,false],"newspaper-x-recent-post-big":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/06\/Comet_on_13_June_2015_NavCam_medium.jpg",305,172,false],"newspaper-x-recent-post-list-image":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/06\/Comet_on_13_June_2015_NavCam_medium.jpg",95,54,false],"web-stories-poster-portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/06\/Comet_on_13_June_2015_NavCam_medium.jpg",305,172,false],"web-stories-publisher-logo":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/06\/Comet_on_13_June_2015_NavCam_medium.jpg",96,54,false],"web-stories-thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/06\/Comet_on_13_June_2015_NavCam_medium.jpg",150,85,false]},"author_info":{"info":["RevoScience"]},"category_info":"Space\/ AstroPhysics<\/a>","tag_info":"Space\/ AstroPhysics","comment_count":"0","_links":{"self":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/4700","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/comments?post=4700"}],"version-history":[{"count":0,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/4700\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media\/4701"}],"wp:attachment":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media?parent=4700"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/categories?post=4700"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/tags?post=4700"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}