Why do we continue to return to Mars?

Humanity has been contemplating Mars for centuries, dreaming of what might be on its orange dust surface. As our telescopes improved, our image of the red planet also improved, although the interpretation of this growing detail by scientists is not always accurate (see: Mars Canals) . The first closely watched Mars mission, Mariner 4, sent home a handful of blurry views of the craters, but the missions that followed – those that succeeded; the overall failure rate is 50% higher for Mars-related spacecraft – it gives a clearer picture of the dust and boulders on the planet.

More recently, scientists have discovered evidence of a warmer and wetter older past for the planet, which could have harbored a life similar to that of the Earth. The search for life therefore continues, even if it now extends to the past. And the planet is less scrambled than Earth with materials from the tectonic movement, so its composition can inform scientists of the formation of the solar system.

NASA's InSight Mars mission, due to end on Monday, November 26, will aim to better understand the planet before any mission and to discover its interior. InSight is a smaller mission than most of the rovers and orbits that precede it, but it's the latest in a long line of robotic emissaries to explore our planetary neighbor. [Missions to Mars: A Robot Red Planet Invasion History (Infographic)]

"Mars is an amazing natural laboratory located right next to Earth," said Lori Glaze, acting director of NASA's Planetary Science Division, at a press briefing for InSight on Nov. 21. "We really want to understand how we conceived of this The diversity of rocky planets in our solar system – they are all very different, each of them is unique in its own way, and trying to understand how they ended up so different is a question very important. "

In addition, despite the failure rate, the planet is relatively easy to land and is less likely to melt our equipment than Venus or Mercury.

The geology of Mars presents plenty of evidence of the water of the past, Glaze added, "so it could have been a place where life could have formed very early in the history of Mars." And of course, trying to understand how his life is or has been spread over our solar planet.System is one of the main issues we have. "

Time capsule of the first planets …

The Earth, Mars and the other rocky planets of our solar system assembled from a dusty disc surrounding the young sun, getting hotter as matter was added and melting into bodies with coats and distinct nuclei. Yet we do not know much about this early history of planets.

"On Mars, this structure has been preserved over the past 4.5 billion years, while on Earth, where we can study it quite easily, this structure has been broken by both plate tectonics, by the convection of the mantle and by the oldest processes have been erased on Earth, "said Bruce Banerdt, lead investigator of the InSight mission and a researcher at NASA's Jet Propulsion Laboratory in California, at the meeting.

So, just like the study of comets – the remnants of this training process – tells researchers the early days of the solar system, interrogating the structure of Mars by measuring the temperature of the planet and marsquakes can tell scientists the next stage of planetary evolution.

And knowing more about the current conditions of Mars can also help researchers understand what it might have been in the past. [Why We’re Obsessed with Mars]

… and the early Earth

"Mars is a very unique place in our solar system because it's one of the few other planets that we think has really been really similar to Earth," said Briony Horgan, science scientist. Planetary University of Purdue, which focuses on the geological history of the moon. and Mars, told Space.com. "Today, it's a cold, inhospitable place, with a very thin atmosphere, low pressure, all the radiations that bathe the surface. But when we look at the geological record of Mars, we see huge amounts of things, like drained river canals. deltas and lake sediments dried up, we see everywhere on the planet minerals that can only be formed in the presence of water. " [Water on Mars: Curiosity Rover Uncovers a Flood of Evidence]

3 or 4 billion years ago, Mars may have looked a lot like the beginning of Earth, Horgan said. While on our planet, plate tectonics and other processes have swept away rocks dating back to that time, Mars offers another chance to see them.

"The geology of Mars has just been so much less active at the Earth 's scale, namely that the rocks of 4 billion years ago are just on the surface", said Horgan. "They have not been subducted, buried, or eroded, they are just sitting there and waiting for us to watch them and try to understand what these 4 billion are-old environments might have looked like, and have- they supported life. "

Horgan is a scientist on NASA 's Mars 2020 rover mission, whose landing site was announced by the agency on November 19. The March 2020 rover follows in the footsteps of two 1976 Viking landers, who landed on the Red Planet in search of life according to scientists. "Better understanding of the conditions of the planet and the Curiosity rover, which landed in 2012 to investigate the past habitability of Mars.

As our vision of the planet evolves, our life search tools have also evolved, said Horgan – after the Spirit and Opportunity rovers have presented evidence of the water of the past, Curiosity has brought a wide range of scientific instruments to try to find organic products or other evidence of habitability. near these old water beds. March 2020 will build on Curiosity's ongoing work by providing even finer analysis tools, such as organic images in rocks, looking for microfossils or textures that suggest ancient biology. Scientists still do not know if there is often water flowing to the surface or if it would have been mostly frozen and melted on occasion because of volcanic activity.

"Some of the 2020 instruments will really focus on the finer details of the rocks, the kind of things we can not see with the instruments we currently have, and cache samples that end up with the Earth could we provide fundamental long-term information, "said John Grant, a geologist at the Smithsonian Institution and a member of the scientific teams of the rover teams Spirit and Opportunity, Curiosity and Mars Reconnaissance Orbiter. He also co-led the Mars 2020 landing site selection process.

"InSight is a very important part of that because none of the [NASA’s previous missions] really – pun intended – scrape under the surface in terms of the evolution of the planet and understand how the planet has evolved over time, "added Grant.

"If we know something about its internal structure and its evolution, we can say how long it has been active, whether it is active or not, and all that has implications for changing conditions. .. in relation to things like livability and where there was a past life, "he told Space.com. Thus, although InSight does not deal directly with life on Mars, "everything is intimately linked," he added.

A neighbour

And, of course, with NASA's evolving plans to send humans to Mars, everything we learn will help us prepare for this moment.

"Yes, we are returning to the moon, but we are also on the way to Mars and science [helps] Make sure we understand the resources and understand the conditions of life and understand what needs to be looked for here, "said Thomas Zurbuchen, Associate Administrator of NASA's Science Mission Directorate, during the meeting. Announcement of the landing site of March 2020.

"This is, I would say, one more argument for why Mars is so exciting for us," he added. "We will not be going elsewhere in the near future of our terrestrial planets, despite all the evidence.March is really the obvious place after the moon to go back and expand our presence in an ever deeper space. . "

So, why do we continue to go on Mars? Learn more about our solar system, learn more about the early Earth, search for life and simply learn more about our neighbor before our visit.

"Science drives our understanding and allows us to bring humans to a place like Mars," Glaze said at the briefing. "The more we explore, the better we understand this environment, the better we will be ready to send humans to Mars in the future."

Email Sarah Lewin at [email protected] or follow her. @SarahExplains. Follow us on twitter @Spacedotcom and on Facebook. Original article on Space.com.