How To Find Life On Mars

2021-02-18   |   by CusiGO

The next very difficult goal of Mars exploration is to find native life. Or at least his remains. NASA’s willpower spacecraft is about to arrive at its destination: it is scheduled to land at 22:00 today (Peninsular time).

The first serious attempt to do so dates back to 1976, when two Viking series spacecraft landed there. Everyone has a small biological laboratory. In particular, it can perform three types of tests to detect certain characteristics of any organism: metabolism, respiration and growth.

The idea is to take small samples from the soil and provide them with nutrients that any terrestrial organism can find. It can be amino acid soup or a mixture of radiolabeled gases. Any Martian organism – if it exists – should absorb and release metabolites that will be analyzed by other instruments on board.

Paradoxically, in order to discover life, it has to be destroyed. The Vikings carried a pyrolyzer, where they burned samples to analyze the combustion products. The first contact between humans and Martians would lead to extinction. Even mild microbes.

The Vikings’ results are ambiguous. One of the test results was positive, and the sun was too weak. The other two, negative. Many scientists – Joan prays among them – point out that this may be due to chemical reactions between soil and nutrients, rather than metabolic processes. Martian soils are reactive, masking the results and making the presence of microbes even less likely. Looking for life on Mars is a much more complex task.

Since then, NASA has adopted a more systematic search program. First, describe the Martian environment to determine whether it was good for life in the past. In particular, thoroughly remove the surface for liquid water. Aerial photos show clear signs: the river is now dry, signs of massive erosion… But it needs to be confirmed on site.

The evidence accumulated step by step. First, thanks to two twins of spirit and opportunity; then, a probe was sent to the polar region. Finally, due to the curiosity of robots, data transmission is still active. It has been exploring the interior of the gale crater for more than two years. The gale crater is an ancient lake that preserves deposits that need water. Long ago, perhaps 3.5 billion years ago, Mars had a milder climate, a denser atmosphere, and lush rivers, lakes, and even shallow waters.

The new robot explorer, willpower, is looking for more direct evidence. It will land on a dry delta of an ancient river that flows into a lake formed inside the jezro crater. There are some signs that too much water is spilling over the edge of the crater.

It can be assumed that in the course of the river, it carries minerals and – perhaps – organic remains, if any. Thousands of years on, they should focus on the alluvial fan, which is where NASA robots are going to move.

Persistence has an articulated arm with an analytical instrument at the end. They are two, designed to detect traces of primitive biological activity. It’s not a matter of looking for living microbes, at least their residues.

One of the two instruments is X-ray spectrometer. Its working principle is to bombard rock samples with radiation beam to produce certain luminescence. The color of this light (technically, its spectrum) depends on its chemical composition. It can identify almost 30 trace elements (calcium, sodium, phosphorus…) and other more exotic elements, such as rubidium, strontium or zirconium.

The other is based on a similar concept, except that it uses ultraviolet light to irradiate the sample, causing the reaction of its molecules. In this case, willpower carries two Raman spectrometers. One is the robot arm, which can approach rocks a few millimeters away. It is particularly sensitive to the existence of carbon chains and rings, and their origin may be biological. Another method works further: it uses a laser to vaporize a small amount of rock remotely and analyze the released gas cloud.

The persevering man carries a chassis, a small drill and a robot manipulator. When any particularly promising terrain is found, it will be sampled and stored in one of the 40 sealed tubes. Some will remain on the ground in place; others will be stored on board.

In both cases, the goal is the same: in the future (maybe six to seven years), another robot will pick them up and bring them back to earth. Its design has little overview, but it will be a collaboration between NASA and ESA. NASA will be equipped with a lander, and ESA will be equipped with an automatic baby carriage to track the traces of bread crumbs like a Martian thumb and collect sample capsules scattered on the ground.

Once they are collected, it will put them in a capsule at the end of a small rocket, which will put them into orbit. There, another probe will collect the cargo and bring it back to earth. With the permission of the Chinese, this will be the first time that scientists have access to raw materials collected directly from the red planet.

Why resort to such a complicated plan? It’s a matter of specialization. Perseverance, which weighs about a ton, is to study the area where samples are collected, but not to bring samples. A returning rocket – apart from the added complexity – would be too heavy. Future collection vehicles will not carry analytical equipment, but only the necessary mechanism to collect capsules and transport them to the ground.

Let’s hope that this project will not be delayed. The device will be powered by solar cells. Perfect for working on Mars with calm weather. But it is estimated that by 2028, the storm season may begin. This will not be the first time that dust clouds have covered the earth as they did in 1971 and 2001. This reduces the available lighting, which will greatly affect future robots. His trip may have to be postponed until the middle of the next decade. Or redesign it to replace solar cells with a nuclear generator immune to dust, which is neither easy nor cheap.

Rafael Clemente is an industrial engineer and the founder and first curator of the Museu de la CI รจ ncia de Barcelona. He is the author of a small step of man.

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