Space Weather Issues in Space Tourism Prof. Dr.-Ing. Uwe Apel Hochschule Bremen Bremen, Germany

Content Introduction Principle health requirements for space tourists Space Tourism and age Preparation for space travel Health risks of space travel Risks associated with the space vacuum Radiation imposed risks Micro-gravity imposed risks Conclusion

Introduction The potential market for space tourism depends on: The interest of people to travel to space The financial ability of people to go to space The physical and mental ability of people to go to space Health issues therefor will have an impact on the demand for space tourism Passenger comfort is an additional aspect closely connected to the health issue Passenger health and comfort aspects are design drivers for the transportation system and in-orbit infrastructure used for space tourism

Possible Types of Space Tourism Suborbital flights (space flight limited to minutes) Orbital flights in a space transportation system (in-orbit stay time less than three days) Orbital flight in a Space Hotel (up to two weeks in-orbit stay time) Space travel to more far destinations e.g. Moon (in-orbit stay times in the order of months)

Principle health requirements for space tourists In the past people travelling to space have been carefully selected on physical, mental and professional performance The minimum physical requirements for space travel are mainly defined by the maximum g-load. They decreased with the advent of the STS and can expected to further decrease with fully reusable space vehicles Mental and professional requirements can be much lower for space tourists than for astronauts or mission specialists because they are passengers instead of system operators

Space tourism and age A large percentage of the human population is able to take the physical strain associated with the launch and re-entry in a shuttle- or post-shuttle type space transportation system There is not upper age limit for space travel as long as the space traveller has a normal health status. Astronaut John Glenn has proven this statement successfully The lower age limit is defined by the ability to act responsible and by the minimum body size required to use the technical equipment (e.g. seats and space suits). Thus, small children may not participate in space tourism.

Preparation for space travel For the typical space tourist, the environment on board of a space transportation system and in a space hotel is totally new and unusual To avoid de-orientation and dangerous behaviour, Space tourists must be prepared for the experience of µg in terms of motion, perception and three-dimensional orientation In addition, the tourists must become familiar with the technical equipment and safety features of the space transportation system and the space hotel

Health risks of space travel Even the best training cannot avoid health risks caused by the nature of space The inherent risks of space travel are associated with the following characteristics of space: Vacuum High energy radiation Micro-gravity

Risks associated with Space Vacuum The main risk is that of an accidental major structural damage to the outer skin of a spacecraft, space hotel or space suit Larger pieces of debris and meteorites are regularly tracked and normally to not impose a danger Typical state of the art micrometeorite shielding will prevent smaller pieces of debris to cause an uncontrollable damage to a spacecraft or space hotel with a high probability EVA’s provide the highest risk which may be compared to that of a diver in the ocean

Radiation imposed risks Solar Cosmic Radiation (SCR): 99% Protons , 1% a-particles , 1 KeV, 0.09 ÷2•109 particles /cm2/s Solar Flares: 1-5 days duration, 89% fast protons ( >30 MeV), 10% a-particles , 1% particles with high charge numbers and energies (10 MeV ÷ 1GeV).High probability during solar maximum occurring every 11 years Galactic Cosmic Radiation (GCR): high-energy particles from outside our solar system, 85% protons, 14% a-particles, 1 % HZE-particles . 10 GeV average energy, variation from 0.1 GeV to 1011 GeV. GCR makes up 5-10% of total radiation in space station orbit

Possible damage by sudden radiation exposure

German dose limits for high-energy radiation

Daily radiation energy dose in a 28.5 ° Orbit Source: Ernst Messerschmid, Reinhold Bertrand, Frank Pohlemann, „Raumstationen - Systeme und Nutzung“, Springer-Verlag, Berlin, 1997

Dose equivalent as a function of stay time in orbit

Radiation dose as a function of shield thickness Source: Ernst Messerschmid, Reinhold Bertrand, Frank Pohlemann, „Raumstationen - Systeme und Nutzung“, Springer-Verlag, Berlin, 1997

Radiation protection requirements Space tourists will not be exposed to excessive radiation loads providing stay times of less than two weeks and a shield comparable to Space Shuttle standards (30g/cm2) Space hotel staff should be exchanged every 6 month to avoid excessive radiation exposure at 30g/cm2 shielding A standard protection of at least 250g/cm2 is highly recommended for an orbital hotel Protection from Solar Flares requires shelters with a shielding of >500g/cm2 for a duration of 5 days EVA’s of space tourists should be limited to less than one hour per trip

Micro-gravity imposed risks A short duration medical problem is the space sickness syndrome. It will last from hours up to five days and can be treated medically. The muscle and bone mass loss problem observed at long duration micro-gravity exposure will impose the space hotel staff. In a space hotel without artificial gravity, the staff should be exchanged every six month to avoid permanent damage of health. Most of the micro-gravity problems can be avoided by providing artificial gravity on board of an orbital hotel. The necessary level of artificial gravity necessary to avoid medical problems isn’t known so far

Comfort aspects of micro-gravity Artificial gravity is desirable not only by medical but also by reasons of passenger comfort A key issue in this context is personal hygiene The rotation of the space hotel necessary to provide artificial gravity does also impose passenger comfort According to Theodore W. Hall four parameters are of importance for the comfort in a rotating space hotel The “apparent” gravity felt by the passenger The gravity gradient in radial direction of the spinning hotel The angular velocity of the housing area The tangent velocity of the housing are

Artificial gravity and the „comfort zone“ Source: Theodore W. Hall, „Artifical Gravity and the Architecture of Orbital Habitats“, International Symposium on Space Tourism, Bremen, March 20-22, 1997

Conclusion A key issue in developing space tourism is the physical and mental ability of people to participate People who are in a good health condition generally can participate Micro-gravity is desired as a unique feature of space but imposes health problems for the space hotel staff Artificial gravity is absolutely required for a space hotel in terms of staff health and guest comfort Radiation is the major health issue in space tourism. The normal radiation background does not impose problems for the typical space tourists but limits the stay time of in-orbit staff Special provisions like „storm shelters“ are necessary to protect from high radiation events like solar flares Health issues do not seem to be „show stoppers“ for the implementation of space tourism