Missions to the Red Planet. (Part 2)

1. Missions to the Red Planet. (Part 2) A look at what technology will be needed for future manned Mars missions Andy Hill (December 2005)

2. 2 Introduction • In Man’s never ending quest to explore and explain the world and universe we live in, Mars has alwaysheld a special significance. • Whether as the god of war to the Romans or the home planet of alien invaders in H.G.Wells’ War of the Worlds, Mars has been constantly present in our thoughts for hundreds or even thousands of years. • Over the last few decades Mars hastaken on yet another persona, theplace where mankind is likely to settle off the planet Earth. • Mars is a harsh and unforgiving planet and half of the missions sent there have failed, the UK’s ill-fated Beagle 2 being the latest casualty, but the human race keep going back unable to satisfy its curiosity. Mars the Good of War

3. 3 Getting to Mars • The first problem faced by a Marsexpedition will be getting there. Today's chemical rockets would take six to eight months to make the journey. • Although there has been much discussion about other possible propulsion systems which would reduce the journey time significantly, suitable hardware is yet to be developed. • Thermal Nuclear rockets and high power Ion thrusters which are the most likely of these alternative systems still only exist as feasibility studies. • Small scale Ion engines have been used to power small robotic spacecraft such as Deep Space 1 and SMART-1 but the the extra thrust required for a large manned vehicle is beyond our present capabilities. Artist’s impression of SMART- 1’s Ion engine in operation - ESA

4. 4 Getting to Mars • The long journey time will have implications for the crew of any Mars mission. Current studies show that prolonged exposure in a weightless environment causes the human body serious problems such as bone and muscle loss. • Astronauts arriving at Mars could find that they did not have enough physical strength to stand up with all the equipment they would have to carry and that their skeleton would be prone to bone fractures. • Added to this, any spacecraft undertaking such a mission would have to shield its crew against harmful radiation during the journey once it ventured beyond the protection afforded by the Earth’s magnetic field. Artist’s impression of Mars Mission Launch - NASA

5. 5 Getting to Mars • It is possible to reduce the effects of weightlessness by having astronauts undertake a rigorous daily exercise program but it is not known whether this would slow down the process enough. • Current thinking is that it might be better to introduce some artificial gravity, possibly generated by spinning the spacecraft either like a bullet or on the end of a tether connected to a counter-weight. This would produce a centrifugal force pushing the crew against the spacecraft’s hull. Astronaut Leroy Chiao exercising on the ISS - NASA

6. 6 Getting to Mars • The radiation hazard is somewhat harder to overcome, the spacecraft’s hull will haveto either reflect or absorb radioactive particles to protect its occupants. On Earth Lead shielding is commonly used for this purpose but this is impractical for a spacecraft due to its weight. Creating a localised magnetic field to deflect radiation is also beyond current technology. • One possibility being investigated is to use the Hydrogen contained in a layer of water within the spacecraft’s hull as a shield. Alternatively arranging the spacecraft’s cryogenic fuel/oxygen tanks around the crew living module could limit the radiation exposure of astronauts. Artist’s impression of craft using cryogenic tank shielding - NASA

7. 7 Getting to Mars • It will be impractical to take all the food, water and Oxygen that the astronauts will need for the long trip to Mars. Its storage and weight would result in a huge craft having to be launched or assembled in orbit. • Food will have to be grown in space enroute to Mars to supplement basic supplies. This will have the advantage of not only producing food but plants will recycle the CO2 produced by the astronauts into breathable oxygen. • Without gravity plants have difficulty absorbing water and nutrients through their root systems but early research on the ISS has been promising and several different food crops such as Peas, Spinach and Wheat have been cultivated. Pea plants grown on the ISS - NASA

8. 8 Getting to Mars • The ISS’s primary source of oxygen is the Russian-built Elektron generator. The device(shown opposite) uses electrolysis to strip oxygen and hydrogen from water. The oxygen is used to sustain astronauts while the hydrogen is dumped overboard. While this approach uses a simple chemical reaction, it is wasteful and recent problemshave shown it to be unreliable. This makes it unsuitable for a Mars mission, where a failure could be fatal. Diagram of Elektron Oxygen generator currently used on the ISS - NASA

9. 9 Getting to Mars • New methods of recycling water will have to be developed. At present fresh water is transported to the ISS on a regular basis and “dirty” water is disposed of, this will not be possible on a trip to Mars where it will be impractical to replenish water enroute. • “Closed loop” systems will have to be designed that clean, filter and remove harmful bacteria/toxins from waste water so that astronauts can reuse it. • Systems will probably rely on plants such as algae to purify water but membrane systems are also being investigated. Any system will need to have high reliability and require low maintenance. An Engineer checks a waste water recycling project (ARMS) at KSC - NASA

10. 10 Living on Mars • Once on the surface the crew will be faced with a number of obstacles, not least of which will be getting around. • To fully explore Mars will require mobility. Current spacesuitswhich are designed foruse in zero gravity are heavy and cumbersomewhich make them unsuitable for Mars’s low gravity. • Martian vehicles will be needed to allow astronauts to cover larger areas and range further across its surface. • Special tools for use by astronauts wearing spacesuit gloves and robots with intelligence to carry loads and perform limited tasks will need to be designed. Astronauts working on Mars - NASA

11. 11 Living on Mars • Today’s spacesuits are made up of several layers and difficult to put on and check out before being used. They maintain a pressure inside (normally less than the 14.5psi found at sea level on Earth, usually about 3-4psi) for the astronaut to work in. The pressure differential with the outside environment has a tendency to inflate the suit making the joints harder to flex and causing the wearer to tire easily. • Modern spacesuit boots are designed for zero G and their soles would quickly wear even in the low Martian gravity as astronauts walk about. • In addition to conventional spacesuits (seen above) NASA is also investigating new light weight designs that are skin tight like a diver’s wet suit which create pressure by constricting the wearer. Mk 3 Spacesuit undergoing testing - NASA

12. 12 Living on Mars • Due to the alignment between Earth and Mars and the travel times involved, it is likely that crews will stay on the Martian surface for extended missions lasting more than a year. This will mean that astronauts will not inhabit small landing craft as they did on the Apollo moon missions and more spacious habitats will be needed. • The Mars Society has been pioneering the use and testing ofproposed Mars habitats in remote locations on Earth (see above photo). The locations are chosen for their extreme conditions to simulate as closely as possible the Martian environment. Teams operate autonomously as if they are on the Martian surface and the data collected is used to refine procedures and equipment. Desert Research Station – MARS Society

13. 13 Living on Mars • Because of their remoteness from Earth, Mars crews will have to either take everythingthey need with them orproduce it from local materials when they get there. • The additional launch weight and logistics of supplying the entire mission from Earth would increase costs to a point that would make it unviable • In-Situ Resource Utilisation (ISRU) is the answer. Mars has the resources necessary to manufacturer everything needed for a long duration mission. • The use of inflatable habitats to act as green houses will enable astronauts to grow much of their own food. Mars Inflatable Habitat - NASA

14. 14 Living on Mars • Later missions will build upon the infrastructure from previous missions and eventually more permanent structures will be built on the surface to produce food for visiting crews or provide sustenance for long stay mission specialists. • At present it is not clear whether the Martian soil will be able to support the growth of food plants but the use of hydroponics to grow plants in water infused with nutrients is an alternative. • Initially the range of food plants will be restricted to a few fast growing high yield varieties but this will be expanded later to add variety to the astronaut’s diet. Mars Greenhouse - NASA

15. 15 Living on Mars • A chemical process first discovered in the 19th century called the Sabatier reaction can be used to produce Methane and water from the thin Martian atmosphere which is composed of 95%Carbon Dioxide. • Electrolysis is then used to split the water into Oxygen and Hydrogen Molecules. • A separate reaction extracts additional Oxygen from the atmosphere for fuel oxydiser and breathable air. • Although the chemical reactions are fairly simple reproducing them on the Martian surface on a scale large enough to provide the fuel, water and Oxygen necessary for an extended mission will be difficult. Chemical Reactions used to make water, oxygen and rocket fuel

16. 16 Living on Mars • To explore a larger surface area vehicles will be needed to cover the Martian terrain. To save space these will probably be transported as a few components ready to be fully assembled when they reach Mars. • Small vehicle may use solar power larger long range vehicles will almost certainly derive power from either nuclear generators (as used by the Viking and Cassini missions) or fuel cell technology using Oxygen and Hydrogen extracted from Martian ice deposits. • The arid dusty conditions on Mars will create problems for vehicles operating there. Joints will have to be sealed against the fine Martian dust and equipment will have to function in extremes of temperature and the high ambient radiation levels caused by the planet’s lack of magnetic field. Mars Vehicle being unloaded from lander - NASA

17. 17 The Return Trip • As has already been mentioned methane can be easily extracted from the Martian atmosphere and it is this that will be the fuel for spacecraft leaving the surface. • NASA will be using methane engines to power its Lunar ascent vehicle and it is hoping to further develop this technology for use on Mars. • Even though the gravity on Mars is less than half that of the Earth, the Martian ascent vehicle will still be relatively small and light making an orbital rendezvous with a large crew return craft necessary for the long journey home. Mars Crew Ascent craft - NASA

18. 18 The Return Trip • Once in orbit the crew will transfer to an Earth return vehicle and a booster will power them on a trajectory sending them coasting back to Earth. Systems will need to be autonomous or controlled locally by the crew due to the long time delays in communicating with Earth. • During the return journey the crew will supplement their diets with food grown on Mars and breathe oxygen extracted from the Martian atmosphere. Earth Return Vehicle - NASA

19. 19 What Will All This Achieve? • There are many reason for going, in fact many more than for not attempting this difficult journey. The financial cost will be great, maybe more than any other space project ever undertaken but the rewards will also be great. Here are only some of the reasons for going. • Space technology has always had spin-offs that enhance our existence on Earth and a programme to visit our nearest neighbour will produce advances in such areas as robotics, virus detection, water purification, remote sensing and image processing. • One of the biggest questions could be answered, are we alone in the universe? If life is discovered on Mars, even microbial life, we will know that it is likely that there our other planets where life has evolved also. It could take a hundred robot missions to discover what one manned expedition would accomplish. • History shows that civilisations have always made advances through exploration. Discovering new ways of doing things and meeting the challenges that present themselves, we are no different we need the challenge of Mars to grow both as individuals and as a society. • Finally consider the alternative, are we going to resign ourselves to never venturing beyond our own world, forever waiting for the next generation to make that journey?

20. 20 What Will All This Achieve? • There is a quotation by Konstantin Tsoilkovsky often repeated within the space advocacy community that still has relevance today. “Earth is the cradle of Mankind. But one does not live in the cradle forever.” • Tsoilkovsky was a Russian Mathematics teacher who developed many of the principles of modern space flight over 8 decades ago. How many more generations will pass before humanity puts a foot print on Mars.

21. 21 Acknowledgements This Presentation would not have been possible without the help of the following organisations and sources: • National Aeronautics and Space Administration (NASA)www.nasa.gov • European Space Agency (ESA)www.esa.int • MarsNews.com –NewsWire for the New Frontierwww.MarsNews.com • The Mars Societywww.marssociety.org.uk