Mission Perseverance: the persistent desire to conquer the sky to descend underground

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Mission Perseverance: the persistent desire to conquer the sky to descend underground
Mission Perseverance: the persistent desire to conquer the sky to descend underground
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For the second time in its history, mankind will launch an aircraft under a foreign sky - and for the first time in history it will be heavier than the local "air". In addition, Perseverance will be able to clarify a number of issues that are of noticeable importance for the study and even colonization of Mars. However, one can predict with a high degree of certainty what he will not be able to: decide the question of whether there is life on Mars. But this is no longer his fault, but the general problem of unmanned expeditions to the Red Planet. We understand the details.

Perseverance Mars rover

In July 2020, NASA sent a new rover to Mars, and yesterday, February 18, it finally reached the surface of the Red Planet. The landing point was the Jezero crater - in the past, a rather large lake, next to which you can still see the dried-up delta of the river that once flowed into this lake.

The name of the crater is similar to the Russian word “lake” because it was named in 2007 in honor of the city of Jezero in the Republika Srpska (Bosnia and Herzegovina), and this word means “lake”.

Hopes for the discovery of life: purely theoretical

The landing site was chosen not so much because there was a reservoir there. There are many former lakes, seas and rivers on Mars. And earlier, the same Curiosity has already passed through such places. But Jezero has something that is rare elsewhere - NASA orbital images showed carbonate rocks running along the edge of this crater. On Earth, these rocks are often a trace of past life.

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It is known that, in theory, cyanobacteria can exist in Martian conditions. In the past of the Earth, they often formed cyanobacterial mats - their fossil remains are also called "stromatolites". On our planet, their age reaches 3.7 billion years, and sometimes the wind exposes the sediments above them so that the traces of ancient cyanobacteria are almost on the surface. In theory, a similar event at Jezero could allow Perseverance to explore the remains of ancient Martian life.

Unfortunately, this is a theory, but in practice, exposed "outward" ancient carbonate rocks can be so strongly altered by wind erosion (bombardment with dust and grains of sand), as well as cosmic radiation, that their study will not allow unambiguously interpreting the find of quite real stromatolites.

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Of course, nearby, literally under tens of centimeters of sand, there may be well-preserved traces of ancient life. But there is nothing to “reach” them: the tools available at Perseverance, like those of its twin brother Curiosity, simply do not allow you to go deeper into the ground for more than a few centimeters.

How does it differ from Curiosity?

We mentioned that the new rover has the same surface drilling systems as the old one, still operating on Mars nine years after landing. But the new car also has some interesting differences.

First, it is the heaviest rover ever built by humans. If Curiosity weighed 900 kilograms, then the new device - 1025 kilograms. The main weighting is the result of changing the six wheels of the car. On Curiosity, the aluminum of the rims was not chosen quite correctly: too thin. As a result, the local soil quickly made holes in it. It is still possible to move, but the permeability from this, of course, did not improve, and the energy consumption during movement increased.

The wheels themselves Perseverance - to increase all the same cross-country ability - added in diameter, amounting to 525 millimeters versus 500 millimeters for Curiosity. The wheel spokes were kept titanium, but bent to improve the overall strength of the wheels. All this is not an empty reassurance: the main reason for the death of all rovers is their getting stuck in the ground. Therefore, the best wheel reliability is of great importance.

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Another important difference: the MOXIE spacecraft, which the old rover did not have. MOXIE will conduct an experiment on the decomposition of CO2 - the main gas in the Martian atmosphere - into CO and O2 (carbon monoxide and oxygen). The theoretical benefit of the experiment is obvious: it will show whether it is realistic to obtain oxygen directly from the Martian "air", where there is practically no oxygen of its own. MOXIE should generate up to 22 grams of O2 per hour for 1230 hours - approximately the same amount of oxygen per unit of time is absorbed by a person under regular physical activity. It would seem that this will help future manned expeditions.

Almost everything is not so colorful. It is more energy-intensive to extract oxygen from the extremely rarefied local atmosphere than when water is simply decomposed into oxygen and hydrogen by electrolysis. The 15 kg MOXIE consumes 300 watts at peak load (though not for a long time). Almost all planners of future manned expeditions believe that they should be landed where water ice is close to the surface of Mars. Having decomposed its water, it is much easier to get oxygen.

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But the rover cannot dig. Therefore, as a victim of intoxication with ethyl alcohol from an anecdote, he has to “look for the keys not where he lost, but under a lantern, where it’s brighter” - to set up not the experiment that is most useful for future expeditions, but one that is allowed by the very limited possibilities of earthly rovers.

The third important difference from Curiosity: the Russian DAN water neutron detector developed by the Space Research Institute of the Russian Academy of Sciences was replaced by the RIMFAX radar, directed downward and emitting at a frequency of 150-200 megahertz. He, unlike a neutron detector, poorly sees water bound in minerals. But it must distinguish between water ice and traces of liquid water at a depth of 10 meters. This is an extremely important instrument: DAN saw water no deeper than a couple of meters. And the deeper, the higher the temperature - and the likelihood of the presence of liquid salt water. True, it is much more difficult for him to distinguish minerals saturated with water, in contrast to a neutron detector.

In theory, some of the samples collected by Perseverance in 2026 can be taken by the next NASA rover and then sent to Earth. The point is that the "transport" rover will be lighter than the "universal" one. And the delivery of samples from Mars to our planet will require an expedition with a huge landing mass: in order to take off from the Red Planet, the fuel will have to be brought from Earth.

Finally, there is one difference that you cannot see with your eyes, but it still warms the soul of the American side. Perseverance has substituted an import substitute for an energy source: on board it is not Russian plutonium-238, but an American analogue, the production of which has finally been established in the United States in recent years. The power of the radioisotope generator on this plutonium remained the same: just over 100 watts, roughly like a powerful incandescent light bulb.

Separate mission: a second aircraft under a foreign sky

Perseverance carries the lightweight Ingenuity drone with it. Technically, this is a coaxial helicopter of the Kamovski type. The blade span is 1, 2 meters, weight - only 1, 8 kilograms. The rotation speed of the blades will be up to 40 revolutions per second. Such huge dimensions and rotation speed are needed because the atmosphere of Mars is 100-150 times less dense than Earth's. Experiments in a sealed chamber have shown that with lower parameters, the device simply will not take off there.

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The power of the drone is up to 350 watts, more than that of the rover's power source. Therefore, the mini-helicopter first accumulates a charge in the onboard lithium battery for 0.27 kilograms, and then flies, but no longer than three minutes.

In order not to leave Ingenuity without a charge, it will not be released from the rover more than a hundred meters.However, for future missions, the situation may change somewhat. In the case of exploring descent into Mars' lava tubes, the drone is potentially almost irreplaceable. The fact is that robots move extremely poorly on difficult ground surfaces (which killed many rovers even on the plain). But flying is a relatively homogeneous occupation, where even without human intelligence, the survival of the apparatus is more likely.

Therefore, drones are almost the only real way to explore Martian lava caves. It is believed that there is a lot of water ice there. And further from the entrance it can be much warmer than on the surface. It would be nice to test both of these hypotheses, because heat and water are good predictors of possible life. By the way, a number of scientists are sure that it is in such tubes that one should look for it on Mars.

Of course, Ingenuity is just the first step on this path. For a full-fledged exploration of the caves, much larger devices will be required, but first you need to check whether even a small, "training" drone can cope there.

If Ingenuity takes off successfully, it will be a huge achievement. Until now, the device, designed for a long flight under the sky of an alien planet, flew only in the USSR - and for a very long time, already in 1984 (the missions "Vega-1" and "Vega-2"). More than 36 years have passed - it's time to finally renew that long-standing achievement.

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Let's summarize. Perseverance is not too expensive (about 2.5 billion dollars) automated mission, which, most likely, will be able to work on Mars for many years. Like all moving space automata, it is not universal enough to solve the question of "is there life on Mars." Even having passed literally a meter above a subsoil bacterial colony, Perseverance cannot reach it in any way: there is no normal drill.

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But this is not its peculiarity: modern planetary rovers, in principle, are deprived of such opportunities. Even stationary lander such as NASA's Insight, which do not require mobility, cannot successfully dig more than tens of centimeters in depth.

However, the limited capabilities of missions to Mars are not forever. With a high probability, in the next ten years, a carrier with the capabilities of the Starship, a larger landing platform than ever created by mankind, will go there. If this happens, people will also be on Mars. And they, of course, will be able to get to the bottom of Martian subsurface life - if it is there, of course. Indeed, unlike robots, our limbs are much more versatile, and our minds are much more flexible.

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