{"id":14779,"date":"2017-03-20T20:33:21","date_gmt":"2017-03-20T12:33:21","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/europes-exomars-spacecraft-begins-lowering-its-orbit\/"},"modified":"2017-03-20T20:33:21","modified_gmt":"2017-03-20T12:33:21","slug":"europes-exomars-spacecraft-begins-lowering-its-orbit","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/europes-exomars-spacecraft-begins-lowering-its-orbit\/","title":{"rendered":"Europe\u2019s ExoMars spacecraft begins lowering its orbit"},"content":{"rendered":"
\"\"
Artist\u2019s concept of the ExoMars Trace Gas Orbiter. Credit: ESA\/ATG medialab<\/figcaption><\/figure>\n

The ExoMars Trace Gas Orbiter, a Russian-launched, European-built spacecraft that arrived at Mars in October, is starting to dip into the upper reaches of the red planet\u2019s atmosphere in a year-long \u201caerobraking\u201d campaign place the observatory in the right position to hunt for methane, an indicator of potential biological activity.<\/p>\n

The effort to reshape the craft\u2019s course around Mars uses aerodynamic drag from repeated dips into the upper atmosphere to gradually drag down the high point of the probe\u2019s orbit from its current altitude of 20,500 miles (33,000 kilometers) to a planned perch 250 miles (400 kilometers) above the Martian surface.<\/p>\n

Ground controllers at the European Space Operations Center in Darmstadt, Germany, are overseeing a series of seven thruster burns to nudge the low point of the spacecraft\u2019s orbit from an altitude of 120 miles (200 kilometers) down to 70 miles (113 kilometers).<\/p>\n

The Trace Gas Orbiter completed the first two burns Wednesday and Saturday, according to H\u00e5kan Svedhem, TGO\u2019s project scientist at the European Space Agency. He said the orbit\u2019s low point was at an altitude of 87 miles (140 kilometers), as of Monday.<\/p>\n

The next orbit-lowering maneuver is scheduled for Tuesday, followed by more burns March 24, March 27, April 1 and April 6.<\/p>\n

\u201cIt\u2019s not ESA\u2019s first experience with aerobraking, but it is the first time we\u2019ve used this technique to achieve a planned science orbit, repeating it for such a long duration,\u201d said Michel Denis, ESA\u2019s ExoMars flight director. \u201cThe mission controllers have worked intensively with our flight dynamics experts to prepare for this challenging phase \u2013 we\u2019re go for aerobraking.\u201d<\/p>\n

The gradual step-down into TGO\u2019s aerobraking orbit allows ground controllers to monitor pressures and temperatures on the spacecraft.<\/p>\n

\u201cThe atmospheric models aren\u2019t perfect, so we have to \u2018feel\u2019 our way down to the start of aerobraking proper,\u201d said Chris White, an ExoMars spacecraft operations engineer, in an ESA blog post describing the aerobraking procedures.<\/p>\n

\"\"
This illustration shows TGO\u2019s current orbit. The aerobraking campaign will tighten the orbit to a circular perch just 250 miles (400 kilometers) from Mars. Credit: ESA<\/figcaption><\/figure>\n

The orbiter will fly in a special orientation as it slices through the rarefied upper layers of the atmosphere, preventing direct communications with Earth at the most critical point of each orbit. As the spacecraft encounters air particles, friction will cause temperatures to rise outside the probe. Models predict the temperatures should be around 158 degrees Fahrenheit (70 degrees Celsius) on the craft\u2019s two power-generating solar arrays during each passage.<\/p>\n

If the temperatures reach 293 degrees Fahrenheit (145 degrees Celsius), or if other temperature and pressure redlines are exceeded, the spacecraft will automatically fire its thrusters to raise its orbit in a \u201cpop-up\u201d maneuver to avoid such extreme conditions on the next orbit, according to ESA.<\/p>\n

\u201cWe\u2019ll closely monitor the solar array temperature and the acceleration of the spacecraft, not only during the first few passages through the atmosphere but throughout the rest of 2017, and adjust the trajectory as needed,\u201d Denis said in an ESA statement.<\/p>\n

Changes in the density of the upper atmosphere caused by dust storms and solar activity make each TGO close approach unpredictable.<\/p>\n

ESA\u2019s Venus Express spacecraft flew deeper into the atmosphere of Venus during its final year of operations in 2014, gathering data about the planet\u2019s thick, toxic atmosphere and giving European engineers experience with aerobraking techniques needed on future missions, starting with TGO.<\/p>\n

NASA has conducted aerobraking maneuvers the red planet with the Mars Global Surveyor, Mars Odyssey and Mars Reconnaissance Orbiter missions.<\/p>\n

The technique saves fuel, reducing the mass of a spacecraft at launch. In TGO\u2019s case, the tradeoff saved around 1,300 pounds (600 kilograms) of fuel, according to ESA.<\/p>\n

The aerobraking campaign will take a two-month hiatus in July and August, when Mars is behind the sun as seen from Earth. The conjunction disrupts normal communications with spacecraft at the red planet, so managers want to temporarily raise TGO\u2019s orbit to a safer altitude before resuming aerobraking at the end of August.<\/p>\n

By early 2018, the repeated passes through the Martian atmosphere should pull TGO\u2019s peak altitude to around 250 miles. Another rocket burn will raise the low point of the orbit to the same altitude, placing the spacecraft in a circular perch to begin regular scientific observations.<\/p>\n

The circular orbit also allows TGO to act as a data relay satellite between Earth and landers and rovers on the Martian surface. ESA and Roscosmos, the Russian space agency, plan to send a stationary landing platform and rover to the red planet in 2020, and TGO will be critical to enable communications for the mission.<\/p>\n

\"\"
Close-up of the rim of a large unnamed crater north of a crater named Da Vinci, situated near the Mars equator, as viewed by the CaSSIS camera aboard the ExoMars Trace Gas Orbiter on Nov. 22, 2016. Credit: ESA\/Roscosmos\/ExoMars\/CaSSIS\/UniBE<\/figcaption><\/figure>\n

The aerobraking maneuvers come after thruster burns in January and February and tilted the angle of TGO\u2019s orbit from a path hugging the Martian equator to one circling at an angle of 74 degrees, permitting greater coverage of the planet.<\/p>\n

TGO\u2019s four science instruments have collected initial data since the spacecraft arrived at Mars on Oct. 19, but the meat of the mission will wait for 2018.<\/p>\n

\u201cThese dress rehearsals enable our science teams to fine-tune their data acquisition techniques including pointing commands, iron out any software bugs, and get used to working with the data, well in advance of the start of the main mission starting next year,\u201d Svedhem said in a press release. \u201cWhat we\u2019re seeing so far is really promising for our science goals.\u201d<\/p>\n

TGO\u2019s camera has taken several test images of Mars, and the orbiter\u2019s two atmospheric measurement suites also completed successful demos. The Russian-made FREND neutron detector, designed to look for signs of water just below the top layer of Martian soil, is also working as expected.<\/p>\n

Svedhem said the science team has no observations planned during the year-long aerobraking campaign, but there may be opportunities to turn on the science payload to test new instrument modes.<\/p>\n

TGO flew to Mars with the Schiaparelli lander, a demonstrator designed to test European entry, descent and landing technologies for the 2020 rover. The lander crashed after prematurely releasing its parachute and turning off its braking rockets due to incorrect altitude data fed to the craft\u2019s computer.<\/p>\n

The orbiter\u2019s chief objective is to tease out the trace constituents of the Martian atmosphere, particularly methane, a gas detected intermittently over the last decade that scientists think could be produced by microbes or undiscovered ongoing geological activity.<\/p>\n

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

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

Artist\u2019s concept of the ExoMars Trace Gas Orbiter. Credit: ESA\/ATG medialab The ExoMars Trace Gas Orbiter, a Russian-launched, European-built spacecraft that arrived at Mars in October, is starting to dip into the upper reaches of the red planet\u2019s atmosphere in a year-long \u201caerobraking\u201d campaign place the observatory in the right position to hunt for methane, […]<\/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":[831,2297,3022,2271,367,1561],"class_list":["post-14779","post","type-post","status-publish","format-standard","hentry","category-news","tag-european-space-agency","tag-exomars","tag-exomars-2016","tag-exomars-trace-gas-orbiter","tag-mars","tag-planetary-science"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/14779"}],"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=14779"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/14779\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=14779"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=14779"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=14779"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}