PD Dr Christine Elisabeth Hellweg Heads the Radiation Biology Department in the Institute of Aerospace Medicine. As a prominent speaker at the first Asgardian Space Science and Investment Congress in Darmstadt, Dr Hellweg answered a few questions from Asgardia Space News

The impact of space radiation remains a major limiting factor for long-term human space flights, including those to Mars. Your most recent research focuses on the effects of space radiation on humans, could you share what radiation protection methods could become available within the next 10 years? What do you think about the protective properties of water (remembering the idea of Elon Musk to wrap Martian spacecraft with water bags)?

The upcoming Moon missions give an opportunity to test a radiation protection vest using female phantoms. This vest could reduce radiation exposure, especially during solar particle events. Furthermore, the Orion spaceship is designed for optimized radiation shielding and in case of a solar particle event, the crew can use the materials to build a radiation shelter. NASA will also test a solar particle event warning system. All these measures are essential to protect from high-dose rate exposure during unpredictable solar particle events.

Materials that are composed of elements with low atomic weight, like hydrogen and water, are preferable to shield energy particles from space radiation. Using the water supply as shielding can save weight.

For the chronic low-dose exposure by galactic cosmic rays, the situation is more complicated, and it is generally assumed that weight constraints prohibit efficient spacecraft shielding, but a habitat on a planetary or Moon surface could be constructed with sufficient shielding. So currently, radiation exposure in deep space can only be limited most efficiently by reducing mission duration.

AstroRad is a radiation protection vest developed by StemRad, a start-up company sponsored by the Israel Space Agency for NASAs Exploration Mission-1. Made of polyethylene to better block harmful protons, AstroRad will cover the phantoms upper body and uterus. Scientists aim to understand how to better protect future crews.

Various strategies to reduce the deleterious effects of galactic cosmic rays were tested in animal experiments, with quite interesting results. Currently, nobody knows whether e.g. dietary measures will be effective in humans, and they cannot be considered in risk assessment as a factor that might increase the number of 'safe days in space'.

In one of your investigations, you studied the influence of Aspergillus and Penicillium fungi on the ISS materials, as well as on the astronauts' life support systems. Tell us, how dangerous are fungi and bacteria for the ISS and the crew, as well as for future lunar and Martian bases, where we will not be able to air a room or wet clean it for disinfection?

The International Space Station (ISS) is on one of the most exceptional work and living places for astronauts and scientists, but, on the other hand, a very confined and isolated habitat in an extreme and hostile environment. This state-of-the-art small enclosed volume accommodates alternating astronaut crews, which face unique circumstances including work under high pressure, a pre-defined diet and restricted hygienic practices, microgravity and radiation. These factors affect the crews immune systems which increases their susceptibility to infection in space and in space analog environments. Therefore, to guarantee the health of the astronauts, serious prevention, monitoring and mitigation measures are implemented by the space agencies to control microbial contamination in human tended space stations. The microbial populations in these human-made environments mainly come from the crew (skin, upper respiratory tract, mouth, and gastrointestinal tract), but also the surrounding environment. This microbial population is further shaped both in diversity and mass by the unique combination of space-environmental factors. Although most of the microorganisms do not pose severe risks for healthy people, the hampered immune system of astronauts combined with limited treatment, isolation, and no immediate return to Earth reinforces the requirements to stringently control microbial contamination.

Some microorganisms might even pose a risk to the material integrity of a spacecraft: these so-called technophilic microorganisms, in particular fungi, are able to corrode alloys and polymers used in spacecraft assembly. Technophilic microorganisms have caused major problems on the former Russian space station MIR, partaking in damage to structural materials as well as malfunctioning of various space systems and equipment. Specifically, filamentous fungi such as Penicillium and Aspergillus species were associated with the progressive destruction of a window in MIR's descent module, and mold on wiring connectors was associated with electrical outages.

Recent analyses of theISSmicrobiome showed that theISS microbial communities are highly similar to those present in ground-based confined indoor environments and are subject to fluctuations, although a core microbiome persists over time and locations. The genomic and physiological features selected by ISS conditions do not appear to be directly relevant to human health, although adaptations towards biofilm formation and surface interactions were observed. Results from different studies allow to question and debate the direct reason of occurring microbial contamination for crew health concern, but a broad range of studies indicate the potential threat towards material damage and degradation due to biofouling or biofilm formation.

Since total inactivation of microorganisms and the inhibition of microbial biofilm formation are almost unachievable, certain sterilization procedures must be applied to reduce microbial contamination. A certain amount of time, power and effort are inevitably required for active reduction and prevention of microbial contamination. Antimicrobial metals like silver, copper and their alloys are the subject of investigation for various applications in the healthcare sector, food industry, as antifouling-surfaces in the marine environment, cosmetics and many more. These materials provide a long lasting, intrinsic antimicrobial effect, which does not require additional maintenance. These constraints render these types of materials ideal candidates for preventing microbial contamination on limited accessible research stations such as theISS.

Future research is needed to cover larger monitoring time series to better understand the microbiome dynamics and adaptation, but also possible transmission from and to humans, as well as to the unique environment in which they live in.

Traveling to the Moon and Mars has become a priority for the world's space powers today. It is also known that in order to maintain physical health of astronauts at adequate levels, a spacecraft travelling into outer space has to be equipped with an artificial gravity device. Tell us, what developments are being carried out in this directionat the Institute of Aerospace Medicine?

The human body is designed for efficiency, which is hardly surprising as its supply of food remained uncertain during many evolutionary stages and conserving strength was important. The result is that the body noticeably reduces all functions and resources that are rarely used or not used at all in the medium to long term. The loss of strength and decrease in muscle mass that amateur athletes start to feel after a few weeks without training can reach significant levels among astronauts living in a weightless environment during prolonged space missions. In the absence of gravity, a loss of considerable muscle and bone mass occurs, bodily fluids move into the upper part of the body and the strain on the entire cardiovascular system is reduced, leading to a drop in performance. In short, degeneration in space takes place in fast-forward mode compared with Earth.

The downregulation of the immune system, as well as muscle and bone mass reduction and vision impairment are common phenomena during long-term stays in weightlessness. There is still a lack of understanding of what the underlying mechanisms are. One explanation could be the lack of input of Earth gravity. Therefore, our studies investigate the effects of the periodic gravitational influences caused by the use of a centrifuge. For the first time, with the AGBRESA bed rest study the use of artificial gravity as a possible means of preventing the negative effects of weightlessness on the human body is being investigated. Effective countermeasures against bone and muscle atrophy must be developed if astronauts are to live in space or on the moon and Marsfor long periods of time. During the three-month AGBRESAstudy with 60 days of bed rest, two thirds of the test participants will therefore be 'rotated' each day while lying in the DLRshort-arm centrifuge in the:envihab aerospace medical research facility.

Within the AGBRESA study, 24 volunteers spend 60 days in the beds. They remain there for 89 days, including the pre-test and recovery phases. All experiments, meals, and leisure pursuits take place lying down during the bed-rest phase. The participants are restricted in their movements, so that the strain on muscles, tendons and the skeletal system is reduced. The beds are angled downwards towards the head end by six degrees. This simulates the displacement of bodily fluids experienced by astronauts in a microgravity environment.

Human physiological research in weightlessness or under simulated conditions is not only important for astronauts to be able to maintain their health and performance in space, but also for people on Earth. Space medicine therefore also encompasses health research for terrestrial applications, in all areas of prevention, diagnostics and treatment. Downregulation of immune system is a common phenomenon during long-term stays in microgravity. There is still a lack of understanding what the underlying mechanisms are. One explanation could be the missing input of earths gravity. Therefore the effects of periodic gravity inputs by using a centrifuge are investigated.

What conditions need to be created in space in order for humanity to procreate? And when do you think the first healthy child will be born in space?

Currently, a pregnancy in space is not in line with radiation protection regulations, based on the recommendations of international expert groups, as the dose limit for an unborn child is 1 mSv (meaning a 1 mSv organ dose to the uterus of the mother until the end of the pregnancy). During a 6-month ISS mission, a dose of around 100 mSv can be accumulated. If we imagine a pregnancy during a deep space mission, the exposure might amount to 500 mSvduring the nine months. Ideally, we have to reduce this dose by a factor of 500! And then, we have to tackle the microgravity effects

When do you think humanity will be able to live permanently on other planets?

Currently, we have no reliable data on this topic to make a prediction.

What in your opinion Asgardia can do to help humankind explore space?

Bring the involved scientists together and spread the fascination of space exploration.

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Christine Hellweg: 'Spread the Fascination of Space Exploration!' - Asgardia Space News