Will humans ever really visit Mars?

Space travel : "By 2100 we will find extraterrestrial life"

Professor Spohn, billionaire Elon Musk wants to send people to the moon. What do you make of it?

It will come that way. Science will not necessarily advance that, but there is a desire to push human boundaries. Whoever has the money will do it too.

Which planet would be the next candidate for human spaceflight?

The Mars. The biggest problem is not a technical one, but a medical one: How do I manage to get people back and forth safely? The time windows for space travel, in which the radiation exposure is reasonably tolerable, are relatively small. We now know that if some missions to the moon had taken place a little earlier or later, the crews would not have survived. Today we know the solar activity and thus the radiation exposure much better. Therefore one is more careful when planning manned space travel.

On the other hand, there will be numerous unmanned projects in the coming years: "Insight "is to explore the interior of Mars, the new space telescopes Cheops and Plato are looking for life outside the solar system and the Esa probe" BepiColombo "will start for Mercury in October. Is planetary research in top form?

Yes, but there is also a bit of coincidence. We have been waiting a long time for some of these missions. "Insight" is two years late and "BepiColombo" has even been postponed a decade. I have accompanied the mission throughout my career, in various capacities. I even had a password for my computer based on a start date of 2009. Bepi was a nightmare at times.

Why did it take so long?

One reason was the technology. Mercury is the closest planet to the Sun. During the day it is up to 430 degrees Celsius, at night minus 170 degrees. The technology has to withstand these conditions. One problem for a long time was that the solar cells did not work properly at the temperatures and the high radiation exposure. In total, we will bring two orbiters close to Mercury. But none of them will land. To land safely, you would need so much technology that there would be no more space for measuring instruments.

What knowledge do you hope to gain?

We are particularly interested in Mercury as a planet of extremes: the temperatures, the radiation ... It also has a strange chemistry and contains much more iron than the other planets. There are various hypotheses of how Mercury came to be, and all of them have to do with processes in the early stages of the solar system. If we could find out more about Mercury, we could better understand how our solar system was formed.

As a scientist, you were responsible for one of the instruments that will be used at "BepiColombo". Why did you quit this post last year?

Bepi flies for seven years, I didn't know if I would still want to do it in my mid-70s. That wasn't exactly a reason to be happy, but in this business you think long-term, across generations. Often you cannot finish what you start yourself. In this respect, planetary research is a bit like building Cologne Cathedral.

To do this, you are still involved in NASA's "Insight" mission. The "Mars Mole" that you developed in Berlin-Adlershof is supposed to land in November. What is his job?

We want to find out how much heat is still coming from the interior of Mars, so what energy it still has available. For this we are building a geophysical observatory. It consists of a seismometer, a magnetic field measuring device and a heat flow device. We drill up to five meters below the surface and measure the temperature increase and thermal conductivity there. We must not go any deeper in the event that microbes slumber at this depth. We don't want to bring them into contact with terrestrial bacteria.

Why is it believed that there are microbes in the Martian soil?

In the early phase of Mars, conditions prevailed that would have allowed life to arise. We know that water flowed over its surface, which was then lost. The question is, is life extinct or just sinking into the ground? That should clarify the "ExoMars mission" of the Esa from 2020 on.

Does that mean the chances of finding life outside of Earth are greatest on Mars?

Mars is most similar to Earth in terms of climate. Venus is of comparable size and mass, but the climate on Mars roughly corresponds to the dry, cold deserts of the earth, for example the Atacama. This question of extraterrestrial life has come to the fore in recent years. Mars has great potential for this. Three years ago I would have said the greatest.

Not any longer longer?

Some now think that Europe and Enceladus, moons of Jupiter and Saturn, offer greater chances of life. But when it comes to the question of which planet we humans could one day colonize, research tends to focus on Mars.

Do you think there is life outside of our solar system?

Hard to say. In the meantime, more and more planetary systems are being discovered. I expect that there will be planets with at least primitive life among them. But I am not sure whether there is another planet with intelligent life within a discoverable distance. In addition, the development phase must also fit: What is the chance that we will discover one of them as long as humanity exists on earth? In addition, the residents would have to have about the same level of technological development in order to be able to communicate with us.

How can one even discover such exoplanets?

With large telescopes. We know the mass of some planets and the radius of others. We would like both to be able to determine the density. This is what Plato is supposed to do, a new type of telescope from Esa, which should go into operation in 2026. From the density we can deduce chemical characteristics and whether it is a planet on which there can be water that theoretically makes life possible. The final proof of life will always be difficult with exoplanets: You can't just go there.

What will planetary research have achieved by 2100?

We will have found life outside of Earth by then, probably more in our solar system than in any other. Most likely on Enceladus. We will have brought samples from Mars and other planets to Earth. And maybe humans will have landed on Mars by 2100.

From September 17th to 21st the EPSC, Europe's largest conference of planetary researchers, will take place at the TU Berlin. More than a thousand scientists from all over the world are discussing the next big goals in space travel.

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