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A pioneer in the search for life in space, today’s speaker in the“Science of the Cosmos. Science in the Cosmos” lecture series”

Gerda Horneck: “We are still not sure how to define life”

  • Microbiologist Horneck is a veteran of space science. Her experiments have traveledto the moon on boardthe U.S.’s historic Apollospacecraft, and been run onRussia’s Mir stationand the International Space Station.
  • Her talk will focus on what scientists know today about the origins of life, the possibility that it may have reached Earth from outer space, whether or not is may exist on other planets, and, if so, how we can set out to find it.
  • In view of the success of the series and the keen interest shown, the BBVA Foundation has opened a windowon its website – – where visitors can view the lectures in the first two editions in original version () and subtitled in Spanish (), with the latest talks added as they take place

Madrid,December 16, 2013.-“If you assemble 50 scientists and ask them to define ‘life’, you will receive at least 51 answers,” remarks microbiologist Gerda Horneck, one of the first scientists to examine the question of whether life can exist and thrive beyond Earth in the extreme environmental conditions of space.

At the age of 74, Horneck is a veteran of space science in the fullest sense of the word.For many years, her research advanced in parallel with the space race between the United States and the Soviet Union. Her experiments have been carried on missions ranging from the U.S.’shistoric Apollo moonshots, to theEuropean Columbus laboratory in the International Space Station currently in orbit.

In a talk titled “Astrobiology, the Quest for the Conditions of Life in the Universe”, Horneck will examine the current state of knowledge on some of the big open questions in science: the origins of life, the possibility that it may have reached Earth from outer space, whether it may exist on other planets and, if so, how to find it.

Horneck, a former Deputy Director at the Institute of Aerospace Medicine of the German Aerospace Center (DLR), is participating inthe third edition of the “Science of the Cosmos, Science in the Cosmos” lecture series on cosmology and astrophysics, inaugurated in 2011, which has brought to Madrid some of the world’s leading specialists in these areas of science. Their talks can be viewed on the BBVA Foundation website, in original version () and subtitled ().

The “signature” of life

Defining life, or the properties that separate a living being from inanimate matter, might seem simple enough, but is very far from it: “It is difficult to determinesomething for which our biosphere is the only example we know,” Horneck points out. “For now, we can only say that all known life forms are characterized by identifical self-replication,evolution through mutation and adaptation, and the existence of a metabolism.”

She ventures a definition that illustrates the complexity of the question: “One can consider ‘life’ as an open autocatalytic chemical system able to transfer its molecular information via self-replication and to evolve via mutations.”

Nor can we be sure about the “signature” of life;the evidence that would signal beyond doubt its presence on a given planet: “If we knew it, we would be a substantial step forward,” says Horneck, who took part in the choice of experiments for the ExoMars mission of the European Space Agency (ESA), which in 2018 will send a rover to Mars. In the absence of one irrefutable proof of life, ExoMars will search for various – morphological microscopic and chemical signatures, among others, that will together tell us whether life could once have existed on Mars. For, of course, “a general conclusion can only be drawn if the results are in agreement.”

For Horneck, it is precisely knowing so little about this area that makes astrobiology so “appealing,” as a discipline thatis moving“from well-established paths to new frontiers.” But astrobiology is not only about the quest for extraterrestrial life. Its over-riding goal is “to attain a better understanding of the principles leading to the emergence of life from inanimate matter, its evolution, and its distribution, thereby building the foundations for meaningful axioms to support a theory of life.”

Testing the Panspermia theory on Apollo missions

When Gerda Horneck first delved into astrobiology, the term didn’t even exist. The supervisor of her PhD thesis set her the question: If DNA travelled from Earth to another planet, would that suffice to start life? This was back in the late 1960s when the space race was at its height. In 1967, Horneck joined the Working Group on Space Biophysics at the University of Frankfurt, and from there moved in 1975 to the Institute of Aerospace Medicine of the German Aerospace Center (DLR), which appointed her its Deputy Director in 1997. In all this time, she continued probing for answers to her supervisor’s question.

Her first space mission, in 1972, was withAmerica’s tenth manned moon flight, on Apollo 16, with an experiment studyingthe effects of cosmic radiation on microorganisms. Horneck has also taken part in the historicApollo-Soyuz mission in 1975, marking the first time U.S. and Russian astronauts exchanged handshakes in space – along with hugs, flags and tree seeds,Russia’sgroundbreaking program on the Mirstation,deorbited in 2001 after fifteen years, and all the campaigns of the SpaceLab carried on American space shuttles, which was grounded for the last time in 2011.

RecenlyHorneck has worked with Europe’s Columbus lab on the International Space Station, where biological systems can be tested under outer space conditions.

“Inhabited” meteorites?

It has now been established that microorganisms are killed by direct exposure to radiation, but not when they are protected by a layer of dust. What this means, Horneck explains,is that microorganisms on the inside of a small meteorite could survive in space for a few weeks at least. This line of research ties in with the Panspermia theory, which holds broadly that life came to Earth from outer space.

“With the advent of space technology, the theory of Panspermia, put forward by Nobel laureate Svante Arrhenius, can now be experimentally tested. It has been found that single bacterial spores would be killed within seconds, due to the burning power of solar extraterrestrial UV radiation. However, the detection on Earth of meteorites that came from Mars has opened the scenario for the so-called Lithopanspermia, i.e., transport via rocks. And we know that several rock-inhabiting microbial communities are capable of surviving the different steps of Lithopanspermia.”

The problem, she goes on, is that there is no way to “determine” whether this has really happened. “If we discovered that life on Mars – if it exists – was based on the same principles as life on Earth,that would be an argument in favor of Lithopanspermia, but it wouldn’t prove it.”

Horneck, incidently, is“convinced that the Earth is not the only inhabited planet in the Universe, but it will be difficult to prove this with the technology currently available.”

A dearth of data on humans’ ability to adapt to space

Although Horneck has not been involved in studies of how radiation affects astronauts, her work in the Institute of Aerospace Medicine has kept her in close contact with developments in the area. “If we look back forty years, it is clear that we have obtained a good survey on the effects of spaceflight on astronaut health, with regard to microgravity, cosmic radiation, a confined habitat, and altered circadian rhythms.”

“But the development of appropriate countermeasures is still in its infancy. The reason for this is the lack of opportunities for human research in space before the U.S. space shuttle era. And the fact that on the International Space Station, the initial crews were so involved in maintenance that there was not much time for investigations in human physiology. Indeed most data so far have been obtained form ground-based simulation studies.”

On the question of space tourism, Horneck affirms that “there is no unacceptable risk,” as long as the trips are short and kept at low altitudes – below 100 km, where passengers are still largely protected from radiation by the Earth’s magnetic field, and provided they have successfully come through the corresponding training and medical checks.

Can man travel to Mars?

Traveling to Mars, though, is a different story. “As long as human Mars missions take 500 or even 1000 days, there are risks that are not yet acceptable and need further investigation. Prominent examples are bone demineralisation in microgravity, and unforeseenexposure to solar particle eruptions. More research is required, with regard expecially to artificial gravity, radiation shelters and faster transport means.”

Any astronauts who do reach Mars,Horneck insists, will need a robut-constructed “functioning laboratory and fully independent habitats. And that will take some time.”

For further information, contact the BBVA Foundation Communication Department (+34 91 374 5210/+34 91 537 3769, ) or visit