ESA’s Astrolab Mission: Making Space a Safer Place
|International Space Station |
On 6th July 2006, European astronaut Thomas Reiter joined the International Space Station Expedition 13 crew. His mission: Astrolab, Europe’s first long-duration mission to the ISS.
Astrolab is deeply embedded in the effort to prepare humans for safe long-duration space travel in the future. Bringing the permanent ISS crew up to three for the first time in three years, Reiter will increase the time that can be devoted to scientific research on the station. His scientific programme has been contributed by institutions across Europe.
As part of the Astrolab mission, Reiter will carry out scientific experiments in the areas of human physiology, biology, physics and radiation dosimetry. This will help Europe to develop experience of long-term scientific utilisation of the ISS, in preparations for the arrival of the European Columbus Lab to the station in 2007. Columbus will contain research facilities that will enable thousands of experiments to be carried out in life sciences, materials science, and fluid physics. It is ESA’s largest single contribution to the ISS. It is also the most expensive project in Europe’s entire history in space.
Radiation Dosimetry Experiments
Astronauts encounter such high levels of radiation in their work that they are classified as radiation workers. Outside of the Earth’s protective atmosphere, highly energetic cosmic rays and solar particles can cause serious damage to human cells. From the digestive system going haywire to genetic mutations and cancer, the effects of radiation exposure are a serious concern for crewed space missions. Dosimetry is the measurement of the dose of ionizing radiation that is absorbed by tissues or materials. It is a vital part of experiments onboard the ISS to help work out how crew radiation exposure can be minimized.
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The ALTCRISS experiment (Alteino Long Term monitoring of Cosmic Rays on the ISS) has been operational since 2005, and continues with the Astrolab mission. It uses a radiation detector to monitor the flow of cosmic rays in different locations on the ISS, including the crew cabin occupied by Thomas Reiter. It will also test various shielding materials for their efficiency in stopping the harmful rays.
Marco Casolino is a researcher at the INFN (National Institute of Nuclear Physics) in Italy, and a member of the science team for the ALTCRISS experiment. He says, "Results from the experiment are particularly important in the design of new shielding materials for spacecraft and habitats for expeditions outside Low Earth Orbit. Hydrogen and hydrogenous materials seem to be the best shields, and other materials such as Kevlar are being considered for inflatable habitats. Bolder designs call for active shielding using superconducting magnets to deflect harmful particles."
Thomas Reiter and his fellow cosmonauts will be testing Kevlar and other materials including Polyethylene, which is currently used in the sleeping quarters of the US section of the ISS. A novel composite material called Nextel/Kapton will also be investigated for its mechanical and shielding properties. Developing effective shielding will be crucial in space agencies’ plans to send astronauts back to the Moon, and eventually to Mars (one of the long-term goals of ESA’s Aurora programme).
The microgravity conditions of long-duration spaceflight act to suppress the immune system of astronauts, making them more susceptible to infection and disease. Since the Apollo missions, astronauts have been returning to Earth with weakened immunity, and many of the early astronauts developed bacterial or viral infections that a healthy person should have been able to fight off easily.
The LEUKIN experiment, jointly devised by Swiss, Italian, and US scientists, aims to provide a better understanding of how this immune suppression occurs. The experiment will use T-lymphocytes, a type of white blood cell that plays a central role in the body’s immune response. In patients with HIV it is these T-cells which are attacked by the virus, eventually leading to serious illness.
Astronaut Thomas Reiter will activate samples of the cells, taken from human blood, on board the ISS. By injecting cell samples with a chemical mixture, he will simulate what would happen in the bloodstream of a body infected by a virus or bacteria. Reiter will then prepare RNA from these cells, to show which genes have been turned on during activation. Scientists back on Earth will later analyse the expression of almost 9000 different T-cell genes using new gene-chip technology, to find out which ones worked normally, and which ones were inhibited by the microgravity conditions.
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Augusto Cogoli, Executive Director of the company Zero-g LifeTec in Zurich, Switzerland, is a member of the LEUKIN science team. He said, "LEUKIN is the continuation of a series of more than a dozen of experiments conducted in space on Spacelab, MIR, and sounding rockets since 1983. In Spacelab-1 we discovered that T cells do not react to a stimulation agent simulating an infection." Subsequent experiments have been carried out using machines that can simulate zero-g on Earth. Under these conditions, researchers have found that many of the genes regulating the T-cell response to infection do not work properly. The LEUKIN experiment will verify these results in true zero gravity. Cogoli said, "Although we cannot extrapolate in-vitro data directly to what may happen in-vivo, i.e. in the immune system of an astronaut, we intend to learn more about the immune system of humans in space."
Thomas Reiter will be involved in other Astrolab experiments with a biological focus – these are called BASE (Bacterial Adaptation to Space Environments) and YING (Yeast in No Gravity). BASE will study how bacteria react to being in the space environment. This is important in many respects, from how bacteria might contaminate the space habitat and endanger health, to how they can be used in positive ways such as in waste recycling and food production systems. YING aims to understand the importance of gravity on the formation of organised cell structures in yeast. The results will be of considerable interest not only to fundamental science but also to the medical field.
Human Physiology experiments
Life on Earth has evolved over billions of years under the constant force of gravity. Take this force away, and strange things start to happen. The body tries to adapt to the new conditions, resulting in changes that can be damaging, especially when astronauts return to the full force of Earth’s gravity. From his previous experience in space, Reiter has observed that whilst weightlessness is "a very pleasant feeling," it does mean that muscles tend to get smaller and weaker, and bones become more brittle. During his mission, he will be acting as the subject of various physiology experiments, all of which aim to discover more about how the lack of gravity affects normal bodily functioning.
Andre Aubert is based at the Laboratory for Experimental Cardiology at the University Hospital Gasthuisberg, Belgium. He is PI of the Cardiocog-2 experiment, which will study the effects of microgravity on the cardiovascular system. He said, "Our heart is under the control of the autonomic nervous system – it works automatically. Gravity, or the lack of it, will disturb this control mechanism. Some astronauts have difficulties standing after returning to Earth." Space crews returning to Earth have also experienced dizziness, increased heart rate and palpitations. Cardiocog-2 aims to discover more about how the lack of gravity causes these problems, especially after long-duration space flight. Recordings of the electrical activity of Reiter’s heart, his blood pressure, and his breathing were made before he left the Earth, during a protocol of normal and controlled breathing, together with a stress test. This protocol will be repeated four times in space. Aubert said, "In space the astronauts are the subjects as well as the researchers – they perform all measurements by themselves." The experiment team will be the first to also make post-flight measurements, around 25 days after Reiter’s return to Earth in December. "This is important to find out how long it takes the body to fully recover from space flight," said Aubert.
|Astronauts lose calcium in their bones and strength in their muscles while in space because of zero-gravity. This image was taken in NASA’s Skylab. |
Credit: National Space Biomedical Research Institute
It is known from measurements on Earth that an increased level of exhaled nitric oxide can give early warning of inflamed airways. Test subjects including asthma sufferers and those subject to occupational dust inhalation have shown this to be a highly accurate warning system. Whereas on Earth dust and other particles will eventually come to rest under the influence of gravity, in space they never settle, and astronauts are likely to inhale them in greater quantities.
Two different NOA (Nitric Oxide Analyser) experiments will be carried out by Thomas Reiter during his mission, using new improved techniques. He will carry out NOA 1 experiments on a weekly basis to assess his airways for inflammation by measuring his exhaled nitric oxide and comparing it to pre-flight measurements. NOA 2 will involve Reiter carrying out the same inhalation-exhalation procedure just before and after a space-walk. It is known that scuba divers often have gas bubbles in their blood following a dive, without experiencing any symptoms of decompression sickness. The occurrence of gas bubbles without symptoms in astronauts following an EVA is not currently known. This experiment will try to establish whether the decompression process following a spacewalk is totally safe, or whether it needs adapting to prevent gas bubbles forming in the bloodstream of the astronauts.
The ISS is providing a unique opportunity to study the long-term effects of microgravity and space radiation on the human body and other biological systems. Understanding the short and long term impact of the hazardous space environment is a necessary and important part of preparations for future long-duration missions. A lot of the basic research has already been done, and the Astrolab mission will build on this knowledge step by step, paving the way to a safer future in space.