Are we on the verge of discovering extraterrestrial life? Harvard astronomer Prof. Dimitar Sasselov visited Leibniz IPHT in Jena and discussed how new technologies are bringing us closer to answering this question. He was invited by Dr. Corinna Kufner, who is launching her new junior research group at Leibniz IPHT to study the photochemistry of the origin of life. Sasselov explained how the light from distant stars could provide clues to the existence of life—and why Jena is well-positioned for scientific breakthroughs.

 

How are new astronomical discoveries bringing us closer to solving the mystery of the origin of life?

Astronomy involves observing stars and the universe on a massive scale. When we think about life, we have only one example—life on Earth. However, we now know that there are planets like ours orbiting other stars. In our galaxy alone, there are likely billions of stars and even more planets. By studying these newly discovered exoplanets, astronomers can search for signs of life, assuming life is widespread across the galaxy.

How does light from distant stars and planets help us understand the conditions that might have led to the origin of life?

When we observe light from distant stars and the planets orbiting them using our most powerful telescopes, we analyze what we call the spectrum—the distribution of different wavelengths of light coming from those planets’ atmospheres. If these planets are similar to Earth, they might show molecular signatures, or “fingerprints,” in that light. We are looking for specific molecules associated with the existence of a biosphere, such as oxygen or methane, which could indicate the presence of life.

How exactly do scientists use light to detect possible signs of life on distant planets?

Using our telescopes, we look for molecular signatures in the light spectrum of exoplanet atmospheres. For example, oxygen is a key indicator of biological activity. We know that a strong oxygen line appears at a specific red wavelength. We design our spectrographs and telescopes to detect these kinds of signatures on distant exoplanets. If we find them, it could suggest the presence of life.

How close are we today to truly discovering extraterrestrial life?

I believe we are very close. For the first time in the history of astronomy and science, we are building advanced telescopes and spectrographs specifically designed to discover signs of life beyond our solar system. I think we could see significant results within the next 10 to 20 years. We are also working hard to find signs of life within our own solar system, and breakthroughs could happen within the same time frame. These are truly exciting times.

What kind of life do you think we might discover?

When astronomers examine the atmospheric signatures of distant planets, the most likely form of life we will detect is microbial biospheres—microbes, and perhaps even plants, but primarily microbes. There are two main reasons for this: First, even today on Earth, microbes are the dominant source of the gases we can detect. Second, for most of Earth’s 4-billion-year history, life was dominated by microbes, not animals or plants. So, microbial life is the most probable and easiest to detect.

What is your impression of Jena as a hub for optics and photonics?

I’ve had a very positive first impression of Jena and the scientific work being done here. Jena may be small on a global scale, but almost half of the major buildings here are dedicated to science, and many more are under construction. To me, that indicates a great deal of momentum and a promising future for new discoveries. I’m very impressed.