{"id":16858,"date":"2014-11-07T18:31:03","date_gmt":"2014-11-07T10:31:03","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/comets-brush-with-mars-more-dramatic-than-expected\/"},"modified":"2014-11-07T18:31:03","modified_gmt":"2014-11-07T10:31:03","slug":"comets-brush-with-mars-more-dramatic-than-expected","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/comets-brush-with-mars-more-dramatic-than-expected\/","title":{"rendered":"Comet\u2019s brush with Mars more dramatic than expected"},"content":{"rendered":"

STORY WRITTEN FOR CBS NEWS \u201cSPACE PLACE\u201d & USED WITH PERMISSION<\/p>\n

\"Artist\u2019s
Artist\u2019s concept of Comet Siding Spring approaching Mars, shown with NASA\u2019s orbiters preparing to make science observations of this unique encounter. Credit: NASA\/JPL<\/figcaption><\/figure>\n

Comet Siding Spring\u2019s close flyby of Mars last month dumped several tons of primordial dust into the thin martian atmosphere, likely creating a brief but spectacular meteor shower with thousands of shooting stars had any astronauts been there to see it, scientists said Friday.<\/p>\n

The comet dust also posed a much more serious threat than expected to an international fleet of spacecraft in orbit around the red planet. While engineers did not think the comet posed a major hazard, the orbiters were maneuvered to put them on the far side of Mars during close approach. Just in case.<\/p>\n

As it turned out, that was a smart decision.<\/p>\n

\u201cAfter observing the effects on Mars and how the comet dust slammed into the upper atmosphere, it makes me very happy that we decided to put our spacecraft on the other side of Mars at the peak of the dust tail passage and out of harm\u2019s way,\u201d Jim Green, director of planetary science at NASA headquarters, told reporters during a teleconference. \u201cI really believe that hiding them like that really saved them, and it gave us a fabulous opportunity to make these observations.\u201d<\/p>\n

Siding Spring, more formally known as Comet C\/2013 A1, originated in the Oort Cloud, a vast realm of icy relics left over from the birth of the solar system 4.6 billion years ago that extends from beyond the orbit of Pluto halfway to the nearest star. It was Siding Spring\u2019s first trip into the inner solar system, a journey that began a million or more years ago when the gravity of a passing star, perhaps, nudged it onto a different trajectory.<\/p>\n

On Oct. 19, the comet passed within about 87,000 miles of Mars at a relative velocity of some 35 miles per second, or 126,000 miles per hour. Had the comet flown by Earth at that distance, it would have been just a third of the way to the moon.<\/p>\n

\u201cWe believe this type of event occurs once every eight million years or so,\u201d Green said. \u201cSo it is indeed a rare opportunity for us to observe this.\u201d<\/p>\n

Three NASA orbiters \u2014 the Mars Reconnaissance Orbiter, the Mars Odyssey and the newly arrived MAVEN \u2014 along with the European Space Agency\u2019s Mars Express and India\u2019s Mars Orbiter Mission all trained their cameras and instruments on the comet or the martian atmosphere to study the possible effects of Siding Spring\u2019s passage.<\/p>\n

MAVEN, an acronym for Mars Atmosphere and Volatile Evolution, was built to study the martian atmosphere. Its Imaging Ultraviolet Spectrograph instrument detected major changes as dust from the comet slammed into atoms and molecules in the upper atmosphere, high-energy collisions that caused the thin air to glow. The spacecraft\u2019s Neutral Gas and Ion Mass Spectrometer detected clear signs of eight ionized metals \u2014 sodium, magnesium, potassium, chromium, manganese, iron, nickel and zinc \u2014 that spiked immediately following the comet\u2019s flyby and then faded away.<\/p>\n

The Mars Reconnaissance Orbiter trained its high-resolution camera on Siding Spring and while the instrument was not able to resolve the nucleus, brightness variations indicated the comet was rotating once every eight hours.<\/p>\n

By analyzing photos taken at different distances, and given the comet\u2019s trajectory and sun\u2019s illumination, Siding Spring could be larger than a mile across or just a few hundred yards.<\/p>\n

\u201cSo we have an exciting time ahead to untangle that,\u201d said Alan Delamere, a co-investigator for MRO\u2019s camera.<\/p>\n

Another instrument on the Mars Reconnaissance Orbiter uses a 130-foot-long antenna to probe the subsurface of the planet with radar. The surface appears sharply defined in images taken just before the comet\u2019s passage. But images in the immediate aftermath are slightly blurred, the result of atmospheric ionization caused by comet dust dust that affected the radar beam as it passed through the atmosphere to the ground and bounced back to the orbiter.<\/p>\n

The amount of dust and its effects on the atmosphere were a surprise. Green said initial modeling indicated Mars would just skirt the edge of Siding Spring\u2019s dust tail. More recent photos taken by the Mars Reconnaissance Orbiter, however, showed the comet\u2019s trajectory was slightly different than expected. And the dust tail was larger than initially believed.<\/p>\n

\u201cThe analysis seemed to indicate Mars would miss the dust tail in a significant way,\u201d Green said. \u201cIn other words, as the comet flies by the dust tail is following the trajectory\u2026. it still would not have reached Mars to any significant amount. The surprise was indeed the dust tail seemed to be larger. The other surprise, the comet wasn\u2019t quite in the same position we thought it was.\u201d<\/p>\n

Most of the particles were very small, tiny fractions of an inch across. But given their extreme velocity, they had a noticeable effect.<\/p>\n

\u201cWith the amount of dust that came in, it\u2019s very possible that these are not just micron size, but they can be quite large, perhaps up to a centimeter size,\u201d Green said. \u201cAnd anything that is of any size could easily destroy a spacecraft given it\u2019s high velocity and hitting in the right location. So, we were speculating the spacecraft would survive (in the dust tail\u2019s path), but I think it\u2019s pretty obvious they wouldn\u2019t have based on the tremendous response of Mars\u2019 atmosphere to the comet tail.\u201d<\/p>\n

By measuring the glow of magnesium ions \u2014 material from the comet that had electrons stripped away in high-energy collisions with particles in the atmosphere \u2014 scientists could make a rough estimate of how much dust must have been deposited as the planet encountered Siding Spring\u2019s tail.<\/p>\n

\u201cAnd the answer we\u2019re coming up with is a few tons,\u201d said Nick Schneider, a leader of the Imaging Ultraviolet Spectrograph team at the University of Colorado at Boulder. \u201cBased on this mass, we can make a rough estimate of what the meteor shower would have looked like, and it\u2019s looking like that meteor shower must have had thousands of shooting stars an hour, possibly what\u2019s called a meteor storm, although we\u2019re still working on the numbers.<\/p>\n

\u201cNumbers aside, it must have been a spectacular meteor shower on Mars,\u201d he said.<\/p>\n

Meteor storms with more than 1,000 per shooting stars per hour are rare in Earth\u2019s sky and whether Siding Spring\u2019s display at Mars was a storm or a very intense shower, \u201cI don\u2019t think anybody on the phone has ever seen that,\u201d Schneider said. \u201cIt\u2019s extremely rare in human history.\u201d<\/p>\n

Asked what an astronaut on the surface might have seen, he said \u201cit would have been truly stunning to the human eye.\u201d<\/p>\n

\u201cNow, we\u2019ve got all these high tech robots around, but I have to say it might be the most sensitive science instrument of all having a human lying outside with dark-adapted vision looking up at that sky and to see many shooting stars happening at once,\u201d he said. \u201cI think it would have been really mind blowing.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"

STORY WRITTEN FOR CBS NEWS \u201cSPACE PLACE\u201d & USED WITH PERMISSION Artist\u2019s concept of Comet Siding Spring approaching Mars, shown with NASA\u2019s orbiters preparing to make science observations of this unique encounter. Credit: NASA\/JPL Comet Siding Spring\u2019s close flyby of Mars last month dumped several tons of primordial dust into the thin martian atmosphere, likely creating a […]<\/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":[3097,367,4247],"class_list":["post-16858","post","type-post","status-publish","format-standard","hentry","category-news","tag-comet","tag-mars","tag-siding-spring"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/16858"}],"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=16858"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/16858\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=16858"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=16858"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=16858"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}