{"id":15709,"date":"2016-02-23T20:22:08","date_gmt":"2016-02-23T12:22:08","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/dizzying-final-few-months-planned-for-rosetta-comet-probe\/"},"modified":"2016-02-23T20:22:08","modified_gmt":"2016-02-23T12:22:08","slug":"dizzying-final-few-months-planned-for-rosetta-comet-probe","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/dizzying-final-few-months-planned-for-rosetta-comet-probe\/","title":{"rendered":"Dizzying final few months planned for Rosetta comet probe"},"content":{"rendered":"
\"Rosetta's
Rosetta\u2019s OSIRIS camera took this image of comet 67P on Jan. 23 at a distance of 75 kilometers (46 miles). Credit: ESA\/Rosetta\/MPS for OSIRIS Team MPS\/UPD\/LAM\/IAA\/SSO\/INTA\/UPM\/DASP\/IDA<\/figcaption><\/figure>\n

Entering the final months of a 12-year mission, Europe\u2019s Rosetta spacecraft is again moving closer to the oddball comet that has engaged scientists since it arrived in 2014, heading for a controlled \u201csmash\u201d landing on the comet\u2019s rugged charcoal-colored surface at the end of September.<\/p>\n

Between now and then, scientists plan to steer Rosetta on trajectories as close as as a few kilometers from comet 67P\/Churyumov-Gerasimenko, guide the probe on an excursion into the comet\u2019s tail, and the complete the mission\u2019s most detailed maps of the tiny tortured world.<\/p>\n

The mission is tentatively scheduled to end the last week of September \u2014 there is some leeway to go a few weeks later \u2014 with a landing on the comet, where Rosetta will join its companion Philae on the surface.<\/p>\n

\u201cThe next few months are probably the most intense the mission has ever seen,\u201d said Matt Taylor, Rosetta\u2019s project scientist at the European Space Agency, in an interview with Spaceflight Now.<\/p>\n

Navigating a spacecraft near such an unconventional space object has not been easy. Navigators must take into account the comet\u2019s chaotic shape and 12.4-hour rotation, and ground controllers threw out the playbook last year as jets of dust and vapor shot out of the nucleus, putting Rosetta in danger.<\/p>\n

Rosetta backed away from comet 67P as it closed in on perihelion, the closest point of the comet\u2019s orbit to the sun, and solar heating activated small eruptions of gas and dust particles into a cloud surrounding the comet\u2019s nucleus.<\/p>\n

The craft\u2019s star trackers, which use stellar positions to compute the probe\u2019s orientation, confused the tiny particles for stars, causing Rosetta to lose its antenna pointing lock on Earth during a close approach to the comet in March 2015.<\/p>\n

The star tracker cameras functioned properly, ESA officials said, but the cloudy haze surrounding comet 67P proved more disruptive than predicted.<\/p>\n

Ground controllers responded by keeping Rosetta\u2019s distance from the comet, guiding the probe clear of the hazardous dust and gas populating the region closest to its core, or nucleus.<\/p>\n

Comet 67P reached perihelion in August, and the comet\u2019s activity is dissipating as it heads for the coldest segment of its six-and-a-half year circuit around the sun.<\/p>\n

The waning warmth as Rosetta and the comet speed farther from the sun allows the spacecraft to move closer to the nucleus than it has since early 2015.<\/p>\n

\"Comet_on_11_September_2015_NavCam_node_full_image_2\"
Rosetta\u2019s navigation camera captured this view of comet 67P on Sept. 11, 2015, from a distance of 319 kilometers (198 miles) as the comet reached peak activity. Credit: ESA\/Rosetta\/NavCam<\/figcaption><\/figure>\n

\u201cWe go as close as we can until the star trackers start to say we can\u2019t track as well,\u201d Taylor said. \u201cWe\u2019re on the edge of the capability of the spacecraft. We can\u2019t say where we\u2019ll be. We\u2019re just going as close as possible.\u201d<\/p>\n

Rosetta has moved as close as 32 kilometers (20 miles) in recent weeks, and the spacecraft will soon venture even closer.<\/p>\n

In April, ground controllers will command Rosetta to veer away from the comet and head for its tail.<\/p>\n

Rosetta will travel up to 1,000 kilometers (620 miles) from comet 67P some time in April, Taylor said, to examine how the solar wind \u2014 a stream of radiation emitted from the sun at more than 400 kilometers per second, or a million mph \u2014 interacts with the comet in space.<\/p>\n

The spacecraft traveled about 1,500 kilometers (930 miles) from the comet in the direction of the sun last year to investigate the solar wind plasma conditions on the day side of the nucleus.<\/p>\n

\u201cIt\u2019s a different environment on the back side of the comet,\u201d Taylor said. \u201cWe\u2019ll be in the tail for about a week.\u201d<\/p>\n

Rosetta has been traveling around the comet in \u201cpyramid-shaped\u201d trajectories around the comet, but the craft will again move into \u201cbound\u201d orbits around the nucleus later this year.<\/p>\n

Taylor said the comet is calming down as expected after perihelion, with current activity about equal to what Rosetta saw in March 2015, when it ran into navigation difficulties close to the nucleus.<\/p>\n

Another priority for Rosetta\u2019s science team is the collection of data for comparative studies to see how the comet\u2019s landscape, composition and other characteristics may differ before and after the brush close to the sun.<\/p>\n

\u201cDoing the before and after look at the comet is one of the most important things,\u201d Taylor said. \u201cWe\u2019re trying to see some stuff we didn\u2019t see (before perihelion) due to the star tracker issues.\u201d<\/p>\n

\"The
The orbit of comet 67P takes it around the sun every 6.5 years, flying beyond Jupiter\u2019s orbit at its farthest point and between the orbits of Earth and Mars at perihelion. Credit: ESA<\/figcaption><\/figure>\n

Rosetta and comet 67P are currently 362 million kilometers (225 million miles) from the sun, nearly twice the distance at perihelion six months ago.<\/p>\n

\u201cWhat\u2019s changed? What\u2019s different? The science we get after (perihelion) is going to be phenomenal,\u201d Taylor said.<\/p>\n

Scientists want to know where comet 67P originated, and the answer could shed light on the violent dynamics of the early solar system, when clumps of rock and ice regularly crashed into each other to construct the planets.<\/p>\n

Comets and asteroids are the leftover building blocks of the solar system, and researchers believe studying such objects could help untangle how water, and potentially the organic constituents of life, spread to the planets.<\/p>\n

Taylor said Rosetta continues to look for the signature of complex amino acids, which merge to form proteins.<\/p>\n

Recent results from Rosetta include confirmation that comet 67P\u2019s interior is fairly uniform and free of large internal caverns, leading scientists to conclude the ultra-low density of the nucleus must be due to the properties of the fine dust and ice that make up the comet.<\/p>\n

Comet 67P formed from the soft collision of two smaller bodies, giving the nucleus its distinctive \u201crubber duck\u201d shape.<\/p>\n

Scientists said an infrared instrument aboard Rosetta also detected outcrops of water ice on comet 67P\u2019s surface, which is mostly blanketed with a dark, gray coating of organic-rich material. Plumes of water vapor erupting from the comet originate underground, where researchers believe much more ice is present.<\/p>\n

Rosetta\u2019s pioneering mission, which began with its launch in March 2004, is nearing an end as the probe and comet head into the outer solar system, where they will eventually pass beyond the orbit of Jupiter. The faint sunlight at such distances is not sufficient to keep the spacecraft\u2019s batteries charged.<\/p>\n

Ground controllers will also be unable to communicate with Rosetta in October as it passes through the same part of the sky as the sun, and the spacecraft\u2019s fuel tanks are running low.<\/p>\n

The end game for Rosetta is to guide the probe to a relatively soft touchdown on comet 67P.<\/p>\n

\"This
This illustration shows comet 67P\u2019s relative size compared to London. Credit: ESA<\/figcaption><\/figure>\n

\u201cThe science team wants to put it near Philae,\u201d Taylor said. \u201cWe don\u2019t know if that fits with the end of mission scenario.\u201d<\/p>\n

Ferried to comet 67P by Rosetta, the Philae lander ended up lodged against a cliff on the small lobe of the comet after bouncing across the nucleus during its descent on Nov. 12, 2014. Starved of sunlight, Philae went into hibernation about two-and-a-half days later.<\/p>\n

Engineers hoped to operate Philae for weeks, and the lander aimed for a relatively flat region in full sunlight. But failures of a thruster, anchoring harpoons and ice screws caused the dishwasher-sized to bounce off the comet despite an on-target descent.<\/p>\n

The tiny world\u2019s tenuous gravitational pull barely kept Philae from flying back into space, and the landing probe tumbled across the comet, striking its surface four times before settling in its final resting place more than a kilometer (3,300 feet) away from its original aim point two hours later.<\/p>\n

But in an astonishingly dramatic twist, Philae survived the rough ride and radioed ground controllers the first-ever measurements from a comet\u2019s surface, including a panoramic photo.<\/p>\n

ESA officials said Philae, a mission led by Germany with significant contributions from France and other European research institutions, completed 80 percent of its planned science observations in the 64 hours it functioned from separation from Rosetta until the probe went to sleep.<\/p>\n

Philae emerged from a half-year snooze as comet 67P moved into warmer conditions last year, and engineers received signals from the lander again on June 13. The probe radioed contacted Earth through a communications relay on the Rosetta mothership seven more times through July 9.<\/p>\n

Then Philae fell silent again, and ground controllers have not heard from the spacecraft in more than seven months.<\/p>\n

With temperatures on the comet falling again, the chances of another contact with Philae are extremely remote, officials said.<\/p>\n

\"Artist's
Artist\u2019s concept of the Rosetta spacecraft deploying the Philae lander before its Nov. 12, 2014, descent to the comet. Credit: ESA\/ATG medialab; Comet image: ESA\/Rosetta\/NavCam<\/figcaption><\/figure>\n

\u201cThe chances for Philae to contact our team at our lander control center are unfortunately getting close to zero,\u201d said Stephan Ulamec, Philae project manager at the German Aerospace Center, DLR. \u201cWe are not sending commands any more and it would be very surprising if we were to receive a signal again.\u201d<\/p>\n

Efforts to establish a stable link with Philae last year were complicated by Rosetta\u2019s distance from the comet, necessitated by the treacherous conditions close to the nucleus.<\/p>\n

Rosetta is now flying back toward the comet, but engineers say temperatures inside Philae\u2019s sensitive electronics are plummeting.<\/p>\n

\u201cWe would be very surprised to hear from Philae again after so long, but we will keep Rosetta\u2019s listening channel on until it is no longer possible due to power constraints as we move ever further from the sun towards the end of the mission,\u201d said Patrick Martin, ESA\u2019s Rosetta mission manager.<\/p>\n

Engineers blame failures in the lander\u2019s radio transmitters and receivers for the intermittent contacts in mid-2015.<\/p>\n

\u201cPhilae has been a tremendous challenge and for the lander teams to have achieved the science results that they have in the unexpected and difficult circumstances is something we can all be proud of,\u201d Martin said. \u201cThe combined achievements of Rosetta and Philae, rendezvousing with and landing on a comet, are historic high points in space exploration.\u201d<\/p>\n

In addition to the high-priority science observations over Rosetta\u2019s final months, the orbiter will try to pinpoint Philae\u2019s location with high-resolution imagery as engineers lower its altitude.<\/p>\n

Analysts narrowed Philae\u2019s location to an ellipse nearly twice as long as a football field, but its exact position is still unconfirmed.<\/p>\n

An image of Philae\u2019s position could help navigators steer Rosetta to a touchdown nearby, and add context to the lander\u2019s observations from 2014.<\/p>\n

\u201cDetermining Philae\u2019s location would also allow us to better understand the context of the incredible in situ measurements already collected, enabling us to extract even more valuable science from the data,\u201d Taylor said. \u201cPhilae is the cherry on the cake of the Rosetta mission, and we are eager to see just where the cherry really is!\u201d<\/p>\n

Detailed planning for Rosetta\u2019s ending should be complete by June. Only then will managers officially decide on the specific timeframe and location for the landing, Taylor said.<\/p>\n

Mission managers say Rosetta will be lucky to survive its crash landing on the comet.<\/p>\n

The spacecraft\u2019s solar panels, which span 32 meters (105 feet) tip to tip, could be damaged or broken at impact, and engineers worry the touchdown could crush antennas, scientific sensors and other equipment mounted on Rosetta\u2019s exterior.<\/p>\n

But scientists hope for centimeter-scale resolution from Rosetta\u2019s camera on final approach, sharp enough to identify small rocks and map the texture of the comet\u2019s dusty landscape.<\/p>\n

\u201cThe main thing is to get as close to the surface as possible,\u201d Taylor said. \u201cBut it\u2019s designed to fly in space, not roll around in the dust. The spacecraft will try to acquire signal once it loses it, and attempt to maneuver. It\u2019s not likely to survive.\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 OSIRIS camera took this image of comet 67P on Jan. 23 at a distance of 75 kilometers (46 miles). Credit: ESA\/Rosetta\/MPS for OSIRIS Team MPS\/UPD\/LAM\/IAA\/SSO\/INTA\/UPM\/DASP\/IDA Entering the final months of a 12-year mission, Europe\u2019s Rosetta spacecraft is again moving closer to the oddball comet that has engaged scientists since it arrived in 2014, heading […]<\/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":[3098,2423,831,3609,3373],"class_list":["post-15709","post","type-post","status-publish","format-standard","hentry","category-news","tag-comet-67p-churyumov-gerasimenko","tag-comets","tag-european-space-agency","tag-philae","tag-rosetta"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/15709"}],"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=15709"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/15709\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=15709"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=15709"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=15709"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}