Professors Heinz-Wilhelm Hübers and Herbert Jahn are two of the scientists who have shaped, and continue to shape, the German Aerospace Center (DLR) to this day. The following is based on a discussion that took place in Berlin about taking measurements and photographs in outer space, as well as a passion for development and the significance of the first Moon landing on 20 July 1969.
ZEISS Stories: Where did you watch the first Moon landing?
Professor Heinz-Wilhelm Hübers: I didn’t watch the Space Race between the US and USSR, I was just a boy at the time. But when the next Moon landings were broadcast on TV in the early and mid-1970s, my parents made sure I watched them. I wasn’t too impressed – the image quality was poor and it was very noisy. However, soon after that I discovered my passion for space travel – I’d been given books on the subject and devoured anything and everything related to aerospace.
Professor Herbert Jahn: I was busy with my dissertation at the time. I watched the first Moon landing on TV early in the morning. As a teenager, I read a popular scientific book from the former East Germany, where I lived with my parents. It was called “Traveling to Distant Worlds” (“Auf dem Weg zu fernen Welten”). It really opened up my world – outer space has fascinated me ever since.
Professor Heinz-Wilhelm Hübers, Director of the Institute for Optical Sensor Systems at the DLR in Berlin. © Marcel Schwickerath
Professor Herbert Jahn helped develop the milestones for aerospace technology. Despite retiring in 2008, he still works on a number of projects today. © Marcel Schwickerath
ZEISS Stories: How important was the first man on the Moon for the subsequent development of space travel?
Jahn: It was groundbreaking in terms of rocket research. In my line of work, I focused on something else, and that was on developing measuring and camera technology. At the Berlin site of the German Aerospace Center, we also analyzed Moon rock that was collected by Russian space probes and brought back to Earth. After German reunification, at the restructured DLR site in the former East Berlin where I worked, we also had access to Moon rock collected during the Apollo missions.
Hübers: This moon rock analysis was very important for the space agency. Planetary material analysis actually involves much more. Besides meteorites, Moon rock and cosmic dust, we don’t yet have a lot of other material of this kind. Here at the Institute, we’re currently working on a project that involves flying to the Mars moon Phobos with our Japanese and French colleagues in order to station a rover equipped with a spectrometer and examine the mineralogy of the surface. One particular challenge is that there is almost no gravity at all on Phobos and due to the distance, the rover and the spectrometer must work largely independently.
Jahn: The Russians were actually much more willing to share their Moon rock than the Americans. We pretty much asked and we got it.
ZEISS Stories: What should one remember when taking photographs in space?
Jahn: That depends on the project. It’s important that the cameras work in space, i.e. in a vacuum. And don’t forget – they first have to survive the rocket launch to even get there at all. What we need is technology that’s built to withstand exposure to strong sunlight and cosmic radiation. The camera lens must always be covered when the camera is not in use. There should be protective layers and a protective tube in front of the lens. The temperature also differs greatly depending on whether you’re taking photos on the sunny side at over 50°C or on the shady side at negative 50. Thermal stresses can lead to deformation. Cosmic particles can destroy the chip in the camera. You can’t just use any old optic.
Hübers: It’s important that the lenses are impermeable to the sun’s rays. This is something we’re also noticing with our Phobos mission. The cameras have to be able to focus with microscope precision. Everything has to be extremely precise. For example, the DLR developed a special autofocus mechanism for the Phobos spectrometer that can independently focus on the object being examined. This demands a great deal of the technology.
ZEISS Stories: What should one bear in mind when performing measurements in space?
Hübers: In space, we fly at satellite speeds of 28,000 kilometers per hour. Everything zips past you – much faster than it does on a high-speed train. And you still need to be able to take clear photos. How can you do this? With extremely short exposure times. And you have to generate data rates in the gigabyte range – that’s per second! Another goal is to recognize structures on Earth that are smaller than one square meter. Nothing should shake or vibrate. This applies to black-and-white and to color photos. This is even trickier when it comes to color photos with several color channels. One of our spectrometers, which was deployed on the ISS at the end of last year to observe the Earth, measures shots with 235 color channels in the visible and near infrared ranges. This means you have even less light per color channel. That’s why the ground resolution is also lower.
Jahn: The problem is that there is little light. If you’d like to observe exoplanets in the depths of outer space, i.e. celestial bodies outside the sun’s gravitational field but below the gravitational field of another star, you must precisely calibrate the camera. This is even more complicated than observing the Earth from space.
ZEISS Stories: How have your working conditions been helping you get developments off the ground?
Jahn: When Germany was divided, we were initially able to support ourselves financially. The USSR and the other communist states worked hand in hand to ensure this. What we lacked was state-of-the-art technology from the West. We were always having to improvise. Once, in the mid-1980s, we were flying back from Moscow. I was sitting beside ZEISS Professor Karlheinz Müller from Jena, who had helped develop a multispectral camera for use in outer space. He told me that we’d missed the boat. He was right – Germany was reunified and it changed our lives completely.
Hübers: What matters to us today is that we have motivated employees at the Institute. That’s where our value lies. The aerospace domain is simply unique. We are the people who look where no human has looked before; who dare to go where no man has gone before. We push the boundaries – and this fascinates students as much as it does engineers. This demands a tremendous effort on our part, so it’s important for us to work together across the globe. Everyone has valuable skills to offer.
Jahn: What ultimately matters is the team. You won’t gain anything fighting alone.
ZEISS Stories: What role did ZEISS technology play during your past developments?
Jahn: Back then, ZEISS built the multispectral camera that Sigmund Jähn took along on his space mission. The company played a crucial role in this development. We played a major role in developing the electronics. Back in the 80s, we joined forces with ZEISS to bring to life a number of projects for remote sensing. One of these concerned ocean wave measurements.
Hübers: ZEISS also developed excellent optical lab systems, some of which we still use today. I use a ZEISS spectrometer when working with my doctoral students. Over the years we have enhanced our data reading capabilities, but the optics are still as pioneering as ever. In optical terms, the company continues to produce outstanding technology to this day.
Jahn: It goes without saying that this high quality can also be found in the large lenses used in space – regardless of whether they were produced in Jena or later on in Oberkochen.
ZEISS Stories: What features do products need to have, e.g. for a manned Mars mission?
Hübers: They have to be incredibly reliable and boast excellent long-term stability. That’s essential. Ever more sophisticated mission goals mean that the requirements on the instruments have risen once more. This concerns optical performance as well as energy, mass and weight – and there’s real pressure to develop. For the space flight itself, we need to take into account the fact that our spectrometer will be deployed on the ISS and is docked on the outside. This begs the question: Is outgassing from the adhesive and plastics contaminating the space station? None of the instruments we use pose any kind of risk for our astronauts.
Jahn: The safety and mobility requirements are much higher, e.g. real-time image recognition. Digitalization, with its fast algorithms and artificial intelligence components, is advancing. The Mars rover, for example, has to be able to detect a rock before it picks it up. But you know what? You can’t plan for every eventuality – often difficult situations arise that are not unlike the one experienced by the researchers and developers during the first journey to the Moon.
Professor Heinz-Wilhelm Hübers is a physicist (with a minor in medicine) and graduate of the University of Bonn. He wrote his doctoral thesis at the Max Planck Institute for Radio Astronomy. Back then, the focus was on developing instruments for radio astronomy, or terahertz astronomy.
In late 1994, he was a post-doc at the German Aerospace Center in Berlin (DLR), which he helped reorganize in the wake of German reunification. He became a professor at the Technical University of Berlin and, since 2014, has been Director of the Institute for Optical Sensor Systems at the DLR while also holding a professorship in experimental physics at the Humboldt University of Berlin.
Professor Herbert Jahn studied physics at the Humboldt University of Berlin in the former Soviet zone. He then began working at the campus of the Academy of Sciences in Berlin, which was integrated into the DLR post-reunification.
He conducted research and worked in the field of plasma physics, where he also achieved his PhD, before moving into the field of aerospace engineering. He helped develop milestones for aerospace engineering – including the Fourier transform spectrometer – and, later, the first digital aerial camera as well. In 1986 he became a professor at the Academy of Science. He retired in 2008 but is still involved in several different projects.