{"id":16910,"date":"2014-10-20T19:15:02","date_gmt":"2014-10-20T11:15:02","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/mars-spacecraft-safe-after-fortuitous-comet-encounter\/"},"modified":"2014-10-20T19:15:02","modified_gmt":"2014-10-20T11:15:02","slug":"mars-spacecraft-safe-after-fortuitous-comet-encounter","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/mars-spacecraft-safe-after-fortuitous-comet-encounter\/","title":{"rendered":"Mars spacecraft safe after fortuitous comet encounter"},"content":{"rendered":"
\"The
The HiRISE camera on NASA\u2019s Mars Reconnaissance Orbiter took these images of comet Siding Spring, the first resolved images of a long-period comet\u2019s nucleus. HiRISE took the pictures nine minutes apart at a range of 138,000 kilometers (86,000 miles) from the comet, yielding a scale of about 138 meters (150 yards) per pixel. Credit: NASA\/JPL-Caltech\/University of Arizona<\/figcaption><\/figure>\n

A fleet of robotic spacecraft orbiting Mars got a front row seat to space history Sunday and lived to tell about it, giving scientists their first close-up look at a comet fresh from a cloud of primordial mini-worlds at the outer reaches of the solar system.<\/p>\n

All five orbiters operating at Mars radioed Earth after Sunday\u2019s flyby of comet C\/2013 A1 \u2014 also known as Siding Spring \u2014 within 87,000 miles of the red planet, a near-miss in cosmic terms.<\/p>\n

NASA\u2019s Odyssey spacecraft, Mars Reconnaissance Orbiter, and the newly-arrived MAVEN probe designed to study the Martian atmosphere used the opportunity to take images and gather data on the comet and its effects on the red planet.<\/p>\n

Carrying a telescopic high-resolution camera, MRO got the best view of Siding Spring, capturing the first resolved images of a long-period comet plunging into the inner solar system.<\/p>\n

MRO\u2019s HiRISE camera, managed by scientists at the University of Arizona, took a picture of Siding Spring from a distance of 138,000 kilometers, or about 86,000 miles.<\/p>\n

It turns out the comet\u2019s nucleus, or rocky-ice core, may be smaller than predicted.<\/p>\n

Telescopic observers had estimated the comet\u2019s nucleus to be about a kilometer, or 3,300 feet, in diameter. HiRISE\u2019s imagery shows the nucleus is less than half that size.<\/p>\n

The camera\u2019s narrow field-of-view, designed to look down at Martian terrain, had to be perfectly aimed at the comet, requiring precise pointing of the spacecraft by engineers at MRO\u2019s control center at Lockheed Martin in Denver.<\/p>\n

Kelly Fast, a program scientist in NASA\u2019s planetary science division, said MRO was equipped to look at the comet\u2019s shape, rotation, brightness, and the composition of its coma, a fuzzy ball of dust and gas released from the nucleus by the warming rays of the sun.<\/p>\n

Scientists say Siding Spring is making its first pass close to the sun after spending billions of years locked in the frozen frontier of the solar system \u2014 a region known as the Oort Cloud at the farthest reaches of the sun\u2019s gravitational influence a light-year away.<\/p>\n

\u201cThe comet was placed there after it formed, we think, in the first million or few million years of the beginnings of our solar system, so it\u2019s a body that\u2019s older than the Earth,\u201d said Carey Lisse, a senior astrophysicist at the Johns Hopkins University Applied Physics Laboratory. \u201cImagine a body that\u2019s about the size of a small Appalachian mountain or Downtown D.C. It\u2019s made roughly half of rocky dust and half of volatile ices like water, carbon dioxide and carbon monoxide.\u201d<\/p>\n

Comet Siding Spring was a remnant left over from the early solar system, where dust and rock accreted to form the planets. Like other objects in the Oort Cloud encircling the sun, Siding Spring was ejected from the inner solar system by the slingshot-like effect of gravity when it came close to one of the budding planets.<\/p>\n

\"Researchers
Researchers used the Pancam on NASA\u2019s Mars Exploration Rover Opportunity to capture this view of comet C\/2013 A1 Siding Spring as it flew near Mars on Oct. 19, 2014. Credit: NASA\/JPL-Caltech\/Cornell Univ.\/ASU\/TAMU<\/figcaption><\/figure>\n

\u201cThe comet comes back every few million years and has never ever been closer to the sun than, we think, maybe Jupiter, Saturn, Uranus or Neptune\u2019s distance,\u201d Lisse said. \u201cThis is its first passage into what we call the water-ice line, where it really starts to boil its water off, so it\u2019s acting very different. It\u2019s also its first passage ever by Mars.\u201d<\/p>\n

Gravity from a passing star likely nudged the comet on a course closer to the sun, beginning a descent toward the planets that could have taken more than a million years.<\/p>\n

Robotic missions have targeted comets before, but the probes have only visited objects that frequently pass near the planets and regularly approach the sun, wearing off the primitive features still possessed by Siding Spring.<\/p>\n

The European Space Agency\u2019s Giotto probe flew by Halley\u2019s comet in 1986 and captured the first image of a comet\u2019s nucleus, and NASA\u2019s Stardust mission collected particles from the coma of comet Wild 2 and returned them to Earth in 2006.<\/p>\n

ESA\u2019s Rosetta spacecraft is currently orbiting comet 67P\/Churyumov-Gerasimenko for a comprehensive survey lasting more than a year. Next month, Rosetta will drop a small daughter probe to attempt the first-ever landing on a comet\u2019s nucleus.<\/p>\n

While such missions got a better look at comets than the repurposed Mars orbiters, comet Siding Spring\u2019s brush by the red planet offered the best chance yet to study a long-period comet making its first sojourn toward the sun.<\/p>\n

\u201cIf we study the comet \u2014 its composition and structure \u2014 it will tell us a lot about how we think the planets were formed,\u201d Lisse said before Sunday\u2019s encounter.<\/p>\n

\u201cWe can\u2019t get to an Oort Cloud comet with our current rockets,\u201d Lisse said. \u201cThese orbits are very long and extended at very great velocities, so this comet is coming to us. It\u2019s a free flyby if you will, and it\u2019s a very fantastic event for us to study.\u201d<\/p>\n

Siding Spring\u2019s encounter with Mars was closer than any known comet flyby of Earth.<\/p>\n

\u201cThink about a comet that started its travel probably at the dawn of man and is just coming in close now, and the reason we can actually observe it is because we have built satellites and rovers, and we\u2019ve now got outposts at Mars,\u201d Lisse said.<\/p>\n

Although the comet was thousands of miles away, officials worried that particles from Siding Spring\u2019s nebulous 300,000-mile-long tail could damage or destroy the orbiters as the comet whizzed past at a relative velocity of 126,000 mph, even though engineers deemed the risk low.<\/p>\n

Ground controllers commanded the spacecraft to change their orbits to duck behind Mars at the time of greatest risk from ice and dust in the comet\u2019s coma.<\/p>\n

NASA said Odyssey, MRO and MAVEN were healthy after Sunday\u2019s flyby.<\/p>\n

Odyssey\u2019s instruments were expected to study the comet\u2019s coma and tail and take imagery in visible and infrared wavelengths, according to Fast.<\/p>\n

MAVEN\u2019s suite of particle detectors and atmospheric sensors were supposed to look for signs of heating or expansion of the Martian upper atmosphere caused by the comet. The orbiter\u2019s ultraviolet imaging spectrometer was also expected to take images of Siding Spring and map its composition.<\/p>\n

The European Space Agency\u2019s Mars Express spacecraft, which has circled Mars since 2003, also survived the comet encounter, and India\u2019s Mars Orbiter Mission was reported in good shape Monday, officials said.<\/p>\n

According to an ESA blog on the Mars Express mission, the craft will downlink data from the comet flyby this week, including observations of the Martian atmosphere, ionosphere and images of Siding Spring itself.<\/p>\n

NASA\u2019s Curiosity and Opportunity rovers on the Martian surface were not in peril, but the robots were programmed to try to take pictures of Siding Spring.<\/p>\n

NASA released an image from Opportunity\u2019s panoramic camera Monday showing Siding Spring hanging in the Martian sky.<\/p>\n

\u201cIt\u2019s excitingly fortunate that this comet came so close to Mars to give us a chance to study it with the instruments we\u2019re using to study Mars,\u201d said Mark Lemmon, an Opportunity science team member Mark Lemmon from Texas A&M University, who coordinated the camera pointing. \u201cThe views from Mars rovers, in particular, give us a human perspective, because they are about as sensitive to light as our eyes would be.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"

The HiRISE camera on NASA\u2019s Mars Reconnaissance Orbiter took these images of comet Siding Spring, the first resolved images of a long-period comet\u2019s nucleus. HiRISE took the pictures nine minutes apart at a range of 138,000 kilometers (86,000 miles) from the comet, yielding a scale of about 138 meters (150 yards) per pixel. Credit: NASA\/JPL-Caltech\/University […]<\/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":[3097,4257,367],"class_list":["post-16910","post","type-post","status-publish","format-standard","hentry","category-news","tag-comet","tag-comet-siding-spring","tag-mars"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/16910"}],"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=16910"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/16910\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=16910"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=16910"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=16910"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}