In February 2021, three spacecraft sent from Earth by three different countries reached Mars simultaneously. It looks like our relationship with the neighbouring planet is beginning to evolve. As always when it comes to an upcoming relationship, it’s good to put things in perspective and understand what to actually expect. What is on Mars and what is not and cannot be there?
Alexei Vladimirovich Malakhov, PhD in physics and mathematics, senior researcher at the Russian Academy of Sciences Space Research Institute and guest on the ‘Question of Science’ programme, tells us.
Is there a chance to conquer Mars?
Devices that work on Mars allow us to get acquainted with the planet and prepare our understanding of what is worth waiting for. The success of the first humans to set foot on this planet depends in large part on this. I think they will certainly set foot there. Another issue is that it will happen very soon, and of course these steps will be very modest at first – at the level of escape in, escape out.
The first manned flight to Mars is a matter of decades. The main problem is radiation. We don’t yet know what we’re going to do on the way there and back and how we’re going to be able to be there – at least for a week – and fly back alive.
Today we have Curiosity for five or seven years – it’s only a ton. The equipment that humans need on Mars already weighs several tonnes. How much time and money do we need to spend on this? Over the next decade, at least in theory, we need to solve the technical problems that are holding us back – radiation, mass, etc. And once we have solved them in theory, we will be working on them for another decade.
If you look at the picture above, you can see all the missions ever sent by humanity to the red planet. In the past, it was just failure after failure and about a 50% chance that a mission would succeed, but now we know that three missions simultaneously managed to reach Mars in a week. This is obviously a big step forward. We are improving. It’s very rare for Mars missions to go wrong now – it’s a major technical advance.
There are now as many as ten vehicles working on Mars at the same time. These are rovers and landing missions. An InSight landing mission, three rovers and the remaining six satellites in orbit around Mars. One of the satellites, Mars Odyssey, has been in orbit for 20 years. All we know about Mars today are the results of the measurements we have made in orbit and on the surface over 20-30 years. This is a clear indication of how far we have come, how well we have learned to fly into space, at least at the level of automated stations. And ultimately, we can study Mars in detail, draw conclusions, build models of Mars and study its environment, which we will probably one day fly into.
When is the best time to fly to Mars?
You can go to Mars at any time. The only question is how long it will take to fly there. Every two years there is a ‘window’ – the moment when Earth and Mars are as close together as possible.
As you know, the Earth and Mars orbit the Sun. And when the Earth is on one side of the Sun and Mars on the other, it’s pointless to fly there. But when they get closer, it makes sense to launch a spacecraft from Earth and fly to Mars before it gets any further away from Earth.
When we fly to Mars, we have to optimise time. Why spend years in space when there are launch windows where we can reach Mars in six months? After all, in-flight mission management is also a job that we try to optimise in some way.
Every two years there is a solar eclipse, when Mars goes behind the Sun and communication with all vehicles is interrupted for a few weeks. This continues for three to four weeks until Mars comes out from behind the Sun (relative to Earth). And this applies to all vehicles driving there. All Mars missions pause and pause their vehicles, rovers or orbiters, they all go into hibernation or automatic mode.
To overcome Earth’s gravity and reach Mars, an upper stage is needed. This is the second stage of the rocket, which is activated in low Earth orbit and in effect sets the interplanetary trajectory of the flight. The latest rovers to fly there weigh about a tonne. Satellites generally weigh the same. This is a typical weight for a vehicle in orbit or on the surface of Mars. A ton is essentially a vehicle. And we want to send a person there with some kind of food… This is one of the technical problems that needs to be solved and that governments and companies are now trying to solve – including with ideas.
It is possible that the interplanetary vehicle will be assembled, as a kit, in orbit, where it will be refuelled and sent from there to Mars. This would require several launches from Earth. We assemble a kind of Lego constructor in orbit and then send it to Mars. There’s another interesting idea on the subject – using the Moon as a launch pad, because it’s easier to launch from the Moon and it’s much easier with gravity there than on Earth. The fuel problem is also discussed. It can either be produced on the Moon, and to this end the Moon is being explored for fuel production, or it has to be transported there. But taking fuel to the Moon and then using it to accelerate to Mars is probably not very profitable.
What are conditions like on Mars?
It’s really hard to survive there. One of the big problems with Mars is that the atmosphere is blown out into space by the solar wind and depleted in this way, or it flies to the cold poles where it settles and can freeze.
2 million years ago it was much the same as it is now. But 2 billion years ago, according to new research, Mars was a very different planet that may well have supported life or created life itself.
Early Earth and early Mars were not so different. But then something went wrong on Mars that didn’t happen on Earth. Modelling what Mars might have looked like in the distant past is based largely on the topography that we now know, and on estimates of how much water there was in general 2-2.5 billion years ago in the Martian climate system. When scientists took this water and distributed it across the topography of Mars, they came up with a giant ocean, a large number of lakes and rivers.
The biggest flaw with this planet was that it was many times smaller than Earth. That’s really a flaw because our main protection against the same fate as Mars is the magnetic field around the Earth. The magnetic field is created by a core inside our planet that rotates. It is in fact a dynamo that once spun, when the Earth was created, and is still spinning from inertia. And Mars is smaller. It has less inertia, at some point the dynamo stopped. This hypothesis is indirectly confirmed by modern measurements of the magnetic currents that are now in the orbit of Mars.
Let’s imagine an early Mars. It has a fairly thick atmosphere, there are clouds, a greenhouse effect, water, good temperature – in short, all the “soup” in which life might have originated. And maybe it originated there, and maybe it’s still there, we don’t know. We just assume that the conditions on Mars 4-3.5 billion years ago may well have made life possible.
Volcanism also creates greenhouse gases. All this leads us to believe that life may well have originated and evolved under such conditions. But what happens next? First we stop the dynamo, the magnetic field disappears and Mars is exposed to the solar wind. The solar wind consists mainly of charged particles, electrons and protons, which our Sun spits out. It doesn’t harm Earth in any way because Earth has a magnetic field. And when it interacts with Mars, the atmosphere literally blows out into space and gets thinner.
There was once a Noya period on Mars, so called because it was really wet. One or two billion years have passed, and the Postnaya era came: it was already completely dry, water was only left on polar glaciers – this is an analogy to our permafrost in the circumpolar region.
A pathetic remnant of the atmosphere remained. Its composition is “not special” as we understand it. There is not much oxygen, but mostly carbon dioxide – 90%. Since there is no atmosphere, no greenhouse gases, the temperature difference is -200 to +30 degrees Celsius. It’s dry there, because water either evaporates or there’s ice somewhere under the surface from which it can’t evaporate. And consequently it is quite difficult to find any rudimentary signs of life of living organisms, bacteria.
Is there life on Mars?
Today’s explorations of Mars are attempts, hoping to find either remnants of the life that originated there and perhaps somewhere in the depths, or to find nothing at all. If life were suddenly found there, it would be an enormous stroke of luck.
The possibility of life is there. After all, life originated on Earth, and we know how it originated: water mixed the elements with each other, and that gave rise to organic matter, which then evolved… In principle, Mars had the same conditions, and precisely during the Noachian era, when there was plenty of water, all the basic elements for life were present. So why wouldn’t it have arisen there?
Conditions on Mars and on Earth were the same. But on Earth, the galactic bones played out in such a way that these conditions lasted long enough for life to develop, whereas on Mars they did not. And from that point of view, the Mars probability didn’t work.
The life that existed there may have struggled and adapted for a time and then moved deep below the surface, where it may still exist today. Either the climate won after all. The machines that work on Mars literally drill centimetres. Even if we never find life at centimetre depth, their work is already a great success!
There is also life deep underground, even a kilometre deep. For example, bacteria, primitive organisms that live in underground lakes. Recently, a report was published about radar that flew around Mars and found large reservoirs of salt water at a depth of 1.5 kilometres. And this is exactly what we have measured with our instruments on Mars today. It’s hot, liquid and full of chemical elements. This confirms our hypothesis that life exists or has existed on Mars.