Its costly, but by exploring the red planet we could solve some of the great mysteries about space and ourselves

When US president Donald Trump called astronauts aboard the International Space Station last week to congratulate Peggy Whitson, who now holds the record for the most time spent in space by a Nasa astronaut, he also asked when he could expect to see humen land on Mars( answer: the 2030 s ). Well, we want to do it in my first word or at the worst in my second word, he joked, so well have to velocity that up a bit.

Nasas not alone in its mission. Space bureaux worldwide “re looking for” Mars, and the coming decades hold numerous plans for manned and unmanned missions. Although other worlds in the solar system hold significant scientific promise( not least Saturns moon Enceladus, which hosts a salty underground ocean and was found to have almost all of the ingredients are necessary to ensure life as we know it about a week ago ), it seems that we just love Mars the most. Too much? I dont think so.

Mars is an especially good mission target due to its proximity to us, and has been easy to see in the sky since the year dot; it is relatively similar to Earth in a number of crucial styles, stimulating it a better bet for manned missions and potential colonisation than any other planet in the solar system. There is still much we do not know about countries around the world and so much science to be done there.

We have loved Mars for centuries. The planet has firmly embedded itself in our culture, so much so that Martian is somewhat synonymous with alien although the foreigners you imagine, from sleek black obelisks to giant Wellsian tin cans or little green humanoids, may vary.

Science-fiction writers Isaac Asimov, Ray Bradbury, Arthur C Clarke, HG Wells, John Wyndham, Robert A Heinlein, Kurt Vonnegut, Philip K Dick have penned thousands of pages about the red planet. Staggeringly influential albums have described otherworldly rock starrings with backing bands of Martian spiders. A story about an cosmonaut( played by Matt Damon) cultivating potatoes on the surface of Mars became a Hollywood blockbuster in 2015, raking in $630 m at box offices around the world. All manner of television programmes have found inspiration in Mars, from Captain Scarlet to Looney Tunes hapless Marvin the Martian.

This cultural interest is mirrored in scientific interest. Our first mission to Mars launched in 1960, and we have attempted more missions to the planet than to anywhere else in the solar system bar the Moon. Given this history, youd be forgiven for thinking that we must know almost all there is to know about Mars by now but thats absolutely no truth to the rumors. For one, were still unsure of how Mars formed. The planet is surprisingly small, and doesnt fit into our models of how the solar system came together. Were not sure how its two small moons formed, either. These lumpy, bumpy rocks have puzzling properties. They may have formed in orbit around Mars, they may be captured asteroids, they may be the result of a giant, shattering impact that knocked material from their mother planet or something else.

We also absence a complete understanding of Marss history. We find signs of past water all over its surface and in its chemistry, and so think it was once much warmer than it currently is in order to support liquid water. However, were not sure how this waterworld changed into the arid hunk we see today. To support widespread water and warmth, Marss atmosphere must have been very thick during the planets youth( likely facilitated by a far stronger magnetic field, which has long since switched off ). Where did it all go?

Then, of course, theres the question of life. Is the planet habitable? Is there, or was there ever, life on Mars ? We dont know enough to be sure either way. Perhaps dormant microbes lie buried deep in the soil, or are happily flourishing in warm underground aquifers away from prying eyes. Perhaps the planet is lifeless and always has been, or life has died out.

ExoMars
An artists impression of the ExoMars Trace Gas Orbiter approaching Mars. Photograph: ESA

Uncertainty aside, there is quite a bit we do know about Mars after all, we have been visiting for more than 50 years. Many of Marss positive attributes are similar to those of our home planet( rockiness, proximity, familiar features ), placing it at the top of the colonisation listing. To learn more, we need more data from both our current missions and those launching in coming years.

Arguably the most famous Mars missions are Nasas rovers: Sojourner( launched 1996 ), Spirit, Opportunity( both 2003 ), and Curiosity( 2011 ). The latter two are still active. There are six other active missions collectively analyse Marss properties and potential habitability, namely Nasas 2001 Mars Odyssey, Maven and Mars Reconnaissance Orbiter, Indias Mars Orbiter Mission( known as MOM or Mangalyaan ), and the European Space Agencys Mars Express and ExoMars 2016 Trace Gas Orbiter.

Mars is set to get pretty crowded in the next decade. Europe and Russia will soon launching ExoMars 2020, a rover-surface platform duo that will seek signs of biological activity. India aims to launch a follow-up to Mangalyaan in 2020, and the same year will see launchings from both China and the United Arab Emirates( their first ever try ). Nasa will launch a lander named InSight, to probe Marss interior, and the Mars 2020 rover, which will not only try to figure out if Mars is( or ever was) habitable, as Curiosity is doing, but will also hunt explicitly for signs of life. The US agency is also planning manned missions and an eventual landing on Mars in the 2030 s.

Despite the uncertainty over scientific fund and supporting in the US, Trump appears to support Nasas focus on Mars. In mid-March, he signed an authorisation bill that procured $19.5 bn in funding for the agency, directing it to focus on deep space and aim for a manned landing. However, PayPal billionaire Elon Musks SpaceX could beat Nasa to it. Musk hopes to use his fortune to build a human colony on Mars in the 2020 s, starting with unmanned render launchings every couple of years from 2018 and a manned launch in 2024( landing in 2025 ). However, Musk is famously ambitious with his timelines; he has altered them multiple times, and admitted that a fair quantity of luck will be needed to achieve them.

There are, understandably, many differing opinions not all of them positive on the idea of focusing so much of our effort on Mars. Travel to the red planet threatens to be incredibly expensive, and publicly funding such programmes may suck money from other areas of scientific research. There are also numerous hurdles to clear( technological, biological, financial, ethical) before we can entertain the idea of feasibly sending humans there, whether it be a one-off fly-by or Musks Earth-Mars shuttle running. Some scientists believe there are more interesting places to explore: Saturns moon Titan; Jupiters moons Europa, Callisto and Ganymede; or Enceladus.

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