Exploring Alpha Centauri with nanosatellites


Interview With Dr. Fritz Merkle

OHB Redaktionsteam
Published on
by OHB Redaktionsteam, OHB SE

Humanity’s age-old dream of visiting the closest solar systems outside our own will soon be in reach. Within just a few decades, nanosatellites will be taking photos of Alpha Centauri. Interview with Fritz Merkle, a member of the Management Board of space and technology group OHB SE.


Dr. Merkle, what precisely is the Breakthrough Starshot project?

Breakthrough Starshot will be launching a large number of mini-satellites in a swarm into space. The aim is for them to fly together quickly enough to reach the Alpha Centauri system within twenty years. Six precursors of these satellites were launched for testing on the OHB-developed satellite Max Valier and the Latvian satellite Venta-1 in 2017.

What is the motivation for the project?

The basic motivation can be found in human nature: We all driven by a strong spirit of discovery. It is believed that modern man emerged and developed in Africa as there was sufficient food and water and the climate was moderate. Yet, that did not stop him from migrating to less hospitable regions such as cold north in Siberia or Alaska. The need to explore is evidently part of our DNA and shapes our behavior. It is precisely this spirit of discovery that is driving us to explore remote regions in space to find out more about them.

Just think of novels such as Jules Vernes’ “From the Earth to the Moon”, which explored such questions long before the first lunar landing. And space was one of the core elements of the Eat-West conflict, driving the Americans to become the first nation to land on the moon.

But the question is why this race to fly to the moon even arose in the first place. After all, the superpowers faced many other challenges which were just as pressing. Yet, it was precisely this dream of discovering new terrain and crossing borders that proved decisive. This pioneering spirit is also spurring scientific missions to other planets.

And now we are to fly to a distant solar system?

Until a few years ago, our solar system marked the boundaries and hardly anyone talked about traveling beyond it. If we do something, we want to be able to experience it ourselves and the next solar system is simply too far away. Subsequently, this “Breakthrough Starshot” idea arose a few years ago. This is a group of people who are sponsoring projects that are challenging the limits of our current knowledge. A further program in the Breakthrough initiative is the search for extraterrestrial intelligence. It is looking at whether we can pick up and understand signals emitted by extraterrestrial life.

How did OHB join Breakthrough Starshot?

The project was launched with funding of USD 100 million contributed by the Russian billionaire Juri Milner, who lives in California. Facebook’s Mark Zuckerberg is also part of the team, while astrophysicist Stephen Hawking, who has since passed away, was on the board as a scientist. OHB came across the initiative by chance: At a conference in Luxembourg, our owner and Chief Executive Officer Marco Fuchs started talking to Pete Worden, whom I already known from earlier days. Worden was director of NASA’s Ames Research Center in California. I had first met him in the mid-1980s at the Airforce Research Lab in Albuquerque, New Mexico, in connection with the Starfire Optical Range. Today, he is in charge of the Breakthrough Starshot project and started talking about it. OHB offered to integrate a number of small chip sats on our Max Valier satellite. Chip sats are a little bit bigger than a stamp but have all the main functions of a satellite including a solar generator and miniature antennae. They are early demonstrators used to develop the mission. These mini-satellites were launched into space in mid-2017.

Why are these satellites flying to Alpha Centauri in particular?

Alpha Centauri is the closest solar system. In addition, the smaller solar system Proxima Centaur is located close by. These two solar systems are around four light years away from us. Scientists suspect that they could also contain earth-like planets with a distance from the central star comparable to that between our earth and the sun. This means that temperatures permitting the existence of water – either as ice or as water vapor – could prevail on such planets.

The aim is to reach a destination at which life familiar to us on the basis of our biology or at least a biology based on carbon and water is theoretically possible. Generally speaking, scientists fundamentally assume that Alpha Centauri could provide such conditions.



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Is it even technically feasible for the satellites to reach Alpha Centauri?

It is obviously a challenge given that Alpha Centauri is around four light years from the earth. This means it will take the satellites four years to reach their destination – provided that they travel at the speed of light. Our rockets currently reach only a small fraction of the speed of light, meaning that they would take thousands of years to get there. One possibility would be to build enormous space ships so that people could get there after eighty generations. However, a space ship cannot survive for thousands of years on the basis of our current technological capabilities. Added to this is the problem of energy: Beyond Pluto there is hardly any sunlight. And obviously, solar cells cannot work without sunlight. For this reason, a new way for a terrestrial object to overcome this distance is being sought.

We assume that an object could survive perhaps 20 years in this environment. Consequently, the microchip would spend 20 years in the dark and freezing cold. When it approaches the other sun, it would start to thaw.

How is it possible for the mini-sats to reach the next solar system so swiftly?

A journey of twenty years means a speed of at least one fifth of the speed of light. We cannot achieve this with rocket engines. However, Peter Worden holds experience in the development of high-performance lasers and is working on transmitting the laser light. The idea is to make the satellites so tiny that they can be accelerated by means of light. Roughly the size of a postage stamp and ultimately weighing perhaps only one or two grams, the satellites will be taken to an altitude of a few hundred kilometers on board a launcher. Then, a folding mechanism will be triggered, releasing a giant sail: a wafer-thin film that is stretched between four very fine wires like a large sail with an area of four by four meters. This works because there is no air in space. The sail is highly reflective.

The satellites must then be aligned to the earth, from which a very strong laser light will be sent up to the tiny satellites. The light is reflected off the mirror, which puts pressure on it, and within a few minutes, the satellites are accelerated to twenty percent of the speed of light. Subsequently, the laser focuses on the next mirror and sends the satellites off one after the other.

Do these lasers already exist?

No. These high-performance lasers do not yet exist and must therefore first be developed. Obviously, you also need suitably dimensioned power stations to generate the electricity for these lasers. Thousands, perhaps even tens or hundreds of thousands of satellites will then be sent out. Very likely, not all of them will survive the journey. In addition, the satellites are to send a signal back to the earth. This cannot be done by a single mini-satellite.

But the satellites are stronger when they work in sync?

Precisely. All the mini-sats will pool their resources: As they approach the other sun, the solar cells will wake up, the computer will go into operation and they will start looking for their neighbors. They will connect to each other via radio and must develop crowd intelligence. Then they will activate their cameras and take pictures. Each mini-sat has a very small laser, with which it reflects signals back. When they all connect and their lasers all send signals synchronously, these signals will reach the earth. The signal will require about four years before we can pick it up. You need a lot of bundled lasers to make sure that something ends up getting back to the earth.

So, the satellites will be taking pictures and sending them to the earth?

Exactly, we want to know what things look like out there. The satellites will take measurements – and, of course, it would be great to get a close-up image. We will also be taking other measurements using everything that we can fit onto these tiny satellites. And, if all goes well, a signal will come back after around 24 years. And because we know roughly when to expect this signal, we will be able to put telescopes into position at the right time to collect the signal. And then we will perhaps know a little more about our universe.

Personal details:

Dr. Fritz Merkle, born in 1950, has been a member of the management board of OHB SE since 2014 and a member of the management board of OHB System AG since 2006. Dr. Merkle holds a doctorate in physics from the University of Heidelberg. From 1993-2000 he was vice-president of Carl Zeiss Oberkochen and Carl Zeiss Jena GmbH. He was also a member of the executive board of the Carl Zeiss Group. Dr. Merkle is a member of the Senate of the German Aerospace Center DLR and board member of the Max Planck and Fraunhofer Institutes.