{"id":187365,"date":"2025-10-09T06:02:18","date_gmt":"2025-10-09T06:02:18","guid":{"rendered":"https:\/\/www.newsbeep.com\/uk\/187365\/"},"modified":"2025-10-09T06:02:18","modified_gmt":"2025-10-09T06:02:18","slug":"robots-on-mars-have-just-seen-the-strange-deep-space-comet-tracing-across-the-martian-sky","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/uk\/187365\/","title":{"rendered":"Robots on Mars have just seen the strange deep-space comet tracing across the Martian sky"},"content":{"rendered":"

What do you do when you want to observe something that’s on the other side of the Sun?<\/p>\n

That’s the problem astronomers faced as October 2025 rolled around and comet 3I\/ATLAS<\/a>, the mysterious interstellar visitor, became lost in solar glare, as seen from Earth.<\/p>\n

\"ImageCredit: NASA, ESA, D. Jewitt (UCLA); Image Processing: J. DePasquale (STScI)<\/p>\n

They knew the deep-space interloper would be lost from our view just as it was making its closest approach to Mars.<\/p>\n

The solution? Get some of the many rovers and spacecraft we have on Mars to try and take a look at it.<\/p>\n

And that’s exactly what’s just happened.<\/p>\n

\"ImageImage of comet 3I\/ATLAS in the Martian sky, as seen by ESA’s ExoMars Trace Gas Orbiter, 3 October 2025. The spacecraft’s camera was trained on the fast-moving comet, which is why background stars appear as streaks. Credit: ESA\/TGO\/CaSSIS<\/p>\n

Between 1 and 7 October, the European Space Agency’s ExoMars Trace Gas Orbiter and Mars Express spacecraft turned their cameras towards comet 3I\/ATLAS as it passed close to Mars.<\/p>\n

These two spacecraft, which are orbiting the Red Planet, had the closest view of the comet of all the space agency’s Martian fleet.<\/p>\n

On 3 October, 3I\/ATLAS passed just 30 million km from them.<\/p>\n

\"AA single frame showing the location of comet 3I\/ATLAS when it was discovered on 1 July 2025. Credit: ATLAS\/University of Hawaii\/NASA
\nA visitor from another star<\/p>\n

The vast, vast majority of comets that we see in the night sky originate from an icy ring of rocks and space debris on the edge of our Solar System.<\/p>\n

But not 3I\/ATLAS. It’s one of only three interstellar comets ever discovered in our Solar System.<\/p>\n

That means it originated from a different star system in our Galaxy.<\/p>\n

And it’s not orbiting the Sun, it’s passing by the Sun, meaning its presence in our cosmic neighbourhood is only fleeting, and will soon be lost from view forever.<\/p>\n

\"DiagramDiagram showing the orbit of comet 3I\/ATLAS. Credit: NASA\/JPL-Caltech<\/p>\n

Since it was discovered in July 2025, astronomers have been pointing our most powerful telescopes at the comet, leading to some amazing images of 3I\/ATLAS<\/a> that show exactly what a deep-space visitor looks like.<\/p>\n

They’ve been able to learn about its composition, including that it contains\u00a0carbon dioxide, water ice, water vapour and carbon monoxide.<\/p>\n

One study even concluded that comet 3I\/ATLAS is likely the oldest comet we’ve ever seen<\/a>. It could be at least 7 billion years old, making it almost twice as old as our Sun.<\/p>\n

\"CometComet 3I\/ATLAS captured by the Gemini Multi-Object Spectrograph (GMOS) on Gemini South at Cerro Pach\u00f3n in Chile, 27 August 2025. Image composed of exposures taken through red, green, blue and ultraviolet filters. Credit: International Gemini Observatory\/NOIRLab\/NSF\/AURA\/Shadow the Scientist. Image Processing: J. Miller & M. Rodriguez (International Gemini Observatory\/NSF NOIRLab), T.A. Rector (University of Alaska Anchorage\/NSF NOIRLab), M. Zamani (NSF NOIRLab)
\nWhat ESA’s Mars missions saw<\/p>\n

The European Space Agency’s ExoMars Trace Gas Orbiter and Mars Express spacecraft used their cameras to observe 3I\/ATLAS in the Martian sky.<\/p>\n

However, these cameras were designed to photograph the surface of Mars just a few thousand km below them, not to observe dim, distant comets in the sky.<\/p>\n

Hence, scientists weren’t sure exactly what they’d see.<\/p>\n

ExoMars TGO used its Colour and Stereo Surface Imaging System (CaSSIS) to capture 3I\/ATLAS, which appears as a white dot, tracing across Mars’s sky in an animation produced by stitching together individual frames.<\/p>\n

\"AnimationAnimation showing comet 3I\/ATLAS in the Martian sky, as seen by ESA’s ExoMars Trace Gas Orbiter, 3 October 2025. Credit: ESA\/TGO\/CaSSIS<\/p>\n

The dot is the centre of the comet: its icy-rocky nucleus and its surrounding coma.<\/p>\n

The nucleus and coma are indistinguishable in the TGO images.<\/p>\n

ESA scientists say capturing a distinctive image of the nucleus would have been like trying to see mobile phone on the Moon from Earth.<\/p>\n

The comet’s coma stretches a few thousand km across, and is generated as frozen ice and gas defrost, due to 3I\/ATLAS getting closer to the Sun.<\/p>\n

That’s why these images, as low-res as they may appear, are so important.<\/p>\n

3I\/ATLAS is getting more active as it approaches the Sun, so every piece of data, every observation, is vital.<\/p>\n

\"BrightBright and dark streaks on Martian volcano Olympus Mons, as seen by the ExoMars trace Gas Orbiter. TGO is designed for observing Mars’s bright surface close-up, not dim comets in space. Credit: ESA<\/p>\n

As it continues to get closer to the Sun, this defrosting material is swept behind the comet in a huge tail.<\/p>\n

The tail is too dim to be seen here, but ESA says it may be visible in future images as it continues to grow.<\/p>\n

“This was a very challenging observation for the instrument.,” says Nick Thomas, Principal Investigator of CaSSIS.<\/p>\n

“The comet is around 10,000 to 100,000 times fainter than our usual target.”<\/p>\n

Mars Express images do not yet show 3I\/ATLAS, ESA says, because its camera’s exposure time \u2013 its light-gathering limit \u2013 is too short at just 0.5 seconds, compared to TGO’s 5 seconds.<\/p>\n

But further analysis and image processing techniques may yet bring 3I\/ATLAS to light in Mars Express images.<\/p>\n

\"AA full colour image of Mars taken by ESA’s Mar Express orbiter.
\nSeeing the light<\/p>\n

Scientists were able to use Mars Express\u2019s OMEGA and SPICAM spectrometers, along with ExoMars TGO\u2019s NOMAD spectrometer, to measure and study the light coming from 3I\/ATLAS.<\/p>\n

This technique, where astronomers analyse an object’s spectrum, can tell them a lot about what the object is made of.<\/p>\n

“At this point, it is uncertain whether the coma and tail were bright enough for a spectral characterisation,” ESA says.<\/p>\n

“Scientists will keep analysing the data over the next weeks and months to try to figure out more about what 3I\/ATLAS is made of and how it is behaving as it approaches the Sun.”<\/p>\n

“Though our Mars orbiters continue to make impressive contributions to Mars science, it\u2019s always extra exciting to see them responding to unexpected situations like this one,” says Colin Wilson, Mars Express and ExoMars project scientist at ESA.<\/p>\n

“I look forward to seeing what the data reveals following further analysis.”<\/p>\n

\"EuropeanEuropean Space Agency infographic showing how some of its spacecraft at Mars and Jupiter may be able to see comet 3I\/ATLAS. Credit: ESA\/ATG Europe
\nOnwards to Jupiter<\/p>\n

ESA isn’t finished with 3I\/ATLAS yet.<\/p>\n

In November 2025, the space agency plans to use the Jupiter Icy Moons Explorer (Juice) mission<\/a> to study it, as it passes close by the spacecraft.<\/p>\n

Juice is on its way to Jupiter, where it will study the planet’s icy moons to search for signs of life.<\/p>\n

Though Juice will be further from 3I\/ATLAS than the Mars orbiters were, it will have the advantage of seeing the comet at its most active, just after its close approach to the Sun.<\/p>\n

However, ESA won’t get data from Juice’s observations until February 2026.<\/p>\n","protected":false},"excerpt":{"rendered":"What do you do when you want to observe something that’s on the other side of the Sun?…\n","protected":false},"author":2,"featured_media":187366,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[90,416,56,54,55],"class_list":{"0":"post-187365","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-space","8":"tag-science","9":"tag-space","10":"tag-uk","11":"tag-united-kingdom","12":"tag-unitedkingdom"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/187365","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/comments?post=187365"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/187365\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media\/187366"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media?parent=187365"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/categories?post=187365"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/tags?post=187365"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}