May/June – 2001
Story Title: The Next Step … Mars or Bust
Author: Dr MIKE NICHOLS
An artist impression of the first human landing on Mars in the year 2020. In the foreground, astronauts conduct scientific observations, recording wind speed with an anemometer and planetary features with a hand-held camera. A dust storm is approaching the cratered area near the landing site. The Martian moons of Phobos and Deimos are visible in the twilight sky.
Dr MIKE NICHOLS visits NASA’s Kennedy Space Center where he had the opportunity to review the Advanced Life Support Project. He reports that, although there are still many obstacles to overcome, plants will play a pivotal role in the first manned mission to Mars.
“. . . and we have lift off, the first manned mission to the planet Mars.”
These are the words that will be broadcast in 2020 from the Kennedy Space Center in Florida if planning proceeds on schedule. In fact, most of the rocket technology to get to Mars is already established: the major problem now is to develop a reliable advanced life support system.
The technology to get to Mars is very similar to that used to travel to the moon. The major differences are that the gravity on Mars is much heavier than on the moon, so more fuel will be required to return from Mars; on the other hand, with the development of the Earth-orbiting international space station, the energy required to get out of earth orbit will be much lower.
The development of a reliable (and user friendly) life support system is one of the keys to travel to the more distant planets in our solar system, and eventually to distant galaxies. Within the Advanced Life Support Project, the major focus is on plants so horticultural science can be expected to have a critical role to play in mankind’s future space exploration (and colonisation). Room service in space is somewhat slow, and extremely expensive (it costs over US$10,000 to send 1kg into orbit), so most of the food for any voyage must be “grown” on board the space vehicle.
The first manned Mars mission is scheduled to take about three years, comprising about two years on the surface of Mars, and about six months for the journey from Earth to Mars (and vice versa). The length of stay on the Red Planet is determined more by the need to have Earth and Mars in the correct juxtaposition to reduce travel time between the two planets, rather than any pre-conceived exploration requirements. Nevertheless, it is planned to establish a base camp on Mars and a key component in this camp will be a greenhouse for crop production.
Food is, however, only a minor part of the equation, as plants will have a much more important role than simply the provision of calories and amino-acids. The space vehicle will, in fact, be required to perform like a mini-Earth and although the plant’s ability to produce food will be important, it will be the capacity of plants to convert carbon dioxide to oxygen, and to purify water (Table 1) that will be the critical factors in interplanetary and intergalactic space travel. The whole advanced life support system will be required to convert all waste products (plant and human) into water and soluble nutrients (using a bioreactor), and to use this nutrient solution to grow plants hydroponically, thus recycling the water and essential minerals.
Daily requirements of a human being in space g/day
Food (dry) 640
Water (in food) 1270
Water (drinking) 2350
Carbon dioxide (to remove) 1140
It is absolutely essential that the carbon dioxide levels in the space vehicle do not exceed 5,000 ppm (normally 340ppm on Earth), or the astronauts will die. So plants will play a major role in converting carbon dioxide to oxygen (and sugars) through the process of photosynthesis.
It is most likely that the carbon dioxide levels in the vehicle will be about 3,000 ppm, and this will result in levels of photosynthesis far in excess of those normally occurring on earth. In fact, at 3,000 ppm the rate of photosynthesis is likely to be two to three times that on Earth.
“Plant researchers Neil Yorio and Lisa Ruffe prepare to harvest a crop of Waldann’s Green Lettuce from KSC’s Biomass Production Chamber (BPC). KSC researchers have grown several different crops in the BPC to determine which plants will better produce food, water and oxygen on long-duration space missions.”
The crops being developed for space cultivation include specialty dwarf wheat, potato, lettuce, sweet potato (kumara), bean, tomato, red beet, spinach, radish and strawberry. These are all being grown hydroponically, but even this technology will have problems in true space because of zero gravity. Plants will also be affected by gravity once the astronauts land on another planet. Systems are currently being developed to grow the plants in zero gravity in types of foam media, where the water and nutrients are injected into the root system.
Zero gravity will also have other problems, for example, plants rely very much on gravity to determine which is “up”. Without gravity, the roots will not tend to grow down, and the leaves and shoots will tend to grow toward the light. Another major difficulty to overcome is sodium. This is a critical mineral in human nutrition but can be a severe constraint in plant growth if the concentration gets too high.
This image is a mosaic of Olympus Mons volcano, the highest point on Mars. The cental edifice of Olympus Mons has a summit caldera 24 km above the surrounding plains. Surrounding the volcano is an outward-facing scarp 550 km. Beyond the scarp is a moat filled with lava, most likely derived from Olympus Mons. Farther out is an aureola of characteristically grooved terrain, just visible at the top of the frame.
Light for photosynthesis will be another problem and will need to be supplied through artificial lamps. The electrical energy for this will come from solar panels and converted into monochromatic light at the two wavelengths which maximize photosynthesis. This is likely to be achieved by using light emitting diodes (LEDs) rather than by the more normal, wide-spectrum discharge lamps.
One of the problems of extended space travel is that the light intensity decreases the further the space vehicle is away from the sun. On Mars, the intensity is about 50% that on Earth, so very efficient solar panels will need to be developed.
Potatoes grown in the Biomass Production Chamber of the Controlled Environment Life Support System (CELSS in Hangar L at Cape Canaveral Air Station). During a 418-day “human rated” experiment, potato crops grown in the chamber provided the equivalent of a continuous supply of the oxygen for one astronaut, along with 55 percent of that long-duration space flight crew member’s calorific food requirements, and enough purified water for four astronauts, while absorbing their expelled carbon dioxide.
I am not sure that I would wish to go three years without eating some fruit, and a future challenge must be to develop a system for growing fruit trees such as apples in space. There will be no room for any flowers or ornamental plants, and this may cause some concern. It has already been noted that astronauts are not inclined to harvest plants in space, because they are the only other living things in what is really a very utilitarian and sterile environment. By including ornamental plants in the space vehicle, they would, of course, contribute toward the production of water and oxygen even though their food value would be zero. Their aesthetic value would be very high.
Tomatoes with ripening fruit. Under Earth’s gravity, the canopy tended to collapse under the fruit-laden stems.
Hangar ‘L’ on the Kennedy Space Center site is where a lot of the research is done, but this work is supplemented by studies carried out at a number of Universities in the USA including Tuskegee, Utah State, Cornell, and Florida universities. At Kennedy Space Center, the Advanced Life Support Project works in a number of different projects, and from a horticultural and hydroponics viewpoint, the studies undertaken in the modified space capsule are probably the most interesting. Here, I was shown potatoes which were some 60cm tall, growing in elevated CO2 and high light intensity – the leaves were green right down to the bottom of the plant.
“A dwarf wheat variety known as Yecoro Rojo flourishes in KSC’s Biomass Production Chamber. Researchers are gathering information on the crop’s ability to produce food, water and oxygen, and then remove carbon dioxide. The confined quarters associated with space travel require researchers to focus on smaller plants that yield proportionately large amounts of biomass. This wheat crop takes about 85 days to grow before harvest.”
One of NASA’s findings is that potatoes produce a water soluble tuberising chemical so that continual cropping with the same solution will, in time, result in tubers being initiated when the plants are very young. The competition between tubers and shoots for carbohydrates is such that the shoots never develop to their full potential, with a resulting loss in yield.
There is an inevitability that mankind will explore and eventually establish colonies on other planets and in other galaxies. This is really no different to the journeys of earlier explorers such as Columbus and Cook. Plants will play a pivotal role in these journeys, and horticultural scientists are well placed to make major contributions towards such voyages as we reach for the stars.
NASA first considered a manned expedition to Mars in the early 1970’s and again in the early 1990’s, but each time the costs seemed prohibitive. The American space program had experienced extraordinary inflation during the 1960’s with President Kennedy’s bold challenge to beat the Russians to the moon, and the US$24 billion price tag wasn’t winning NASA many friends. Instead, the Space Shuttle program (only partially successful in its efforts to employ reusable technology and make access to space cheap), won the day and has been followed by the new International Space Station with an estimated total cost of AU$42 billion.
While low orbit costs may have dominated space activities in recent decades, the flame hasn’t died. There is growing support in the US and around the world for a human expedition to the Red Planet. On a recent speaking tour in Australia, world renowned Mars exploration and colonisation expert Dr Robert Zubrin, praised by NASA for his Mars Direct Mission Plan, said that four astronauts would lead the way on the six month direct journey to Mars using a modified version of the Space Shuttle booster system. The explorers would spend 500 days on the Martian surface, during which time they’d use modest amounts of transported hydrogen to convert atmospheric carbon dioxide into methane and oxygen for use in rockets to boost them back to Earth. These pioneers would be the most isolated humans in history – at the very minimum they’d experience a four and a half minute (one way!) delay in their radio transmissions to Earth. Subsequent travellers would ride in a life support capsule tethered to a rotating counter balance used to simulate Martian gravity during the months required to reach the Red Planet.
NASA elaborated this concept in the early 1990’s and arrived at a AU$92 billion price tag – Zubrin claims it can be done for less than half this cost with off-the-shelf technology. The NASA plan called for heavy use of nuclear power and thermal rockets; the Zubrin plan emphasises reliance on ISRU (In Situ Resource Utilisation), using existing resources on Mars to synthesise vital materials.
Controversy over the approach centres around risk – some claim any problem with ISRU would leave astronauts stranded on Mars, that expensive redundancy cannot be avoided. With NASA funding, Zubrin demonstrated in 1997 that sufficient quantities of methane and oxygen could be produced from carbon dioxide (95% of the Martian atmosphere), using small amounts of hydrogen and relatively simple equipment transported from Earth.
These highly successful tests have many wondering if a far less costly mission might be possible after all. Zubrin’s plans do not stop there – his vision of Martian colonisation is reminiscent of human exploration and settlement of the Earth over the last half of the second millennium.
As founding member and President of the International Mars Society, Robert Zubrin has harnessed the energy of space luminaries including high profile astronaut Buzz Aldrin and NASA astrobiologist Dr Chris McKay. The recent loss of the Mars Polar Lander robot has also placed the spotlight on the fourth rock from the Sun, and two major motion pictures will launch it squarely into the public imagination. Touchstone’s Mission to Mars and Paramount’s Red Planet with Val Kilmer (set for a November release), both tell the story of human expeditions to Mars.
Advanced Life Support
Right now, we do not have the life support technology to send people to Mars. That’s life support for extended space missions of one to three years without resupply from Earth. A manned mission to Mars is a six month journey there, perhaps 500 days on the surface, and a six month return journey to Earth. Although there are many potential uses for advanced life support systems, the main thing on everyone’s mind is Mars. One researcher reports they even have buttons that say “Mars or Bust”.
NASA’s Advanced Life Support researchers say they will have an advanced life support system ready for a three-year manned mission to Mars within 10 years. However, there are lots of other technical and political issues that will decide when and if NASA actually send people to Mars.
The human exploration of Mars currently lies at the ragged edge of achievability. The necessary technical capabilities are either just available or on the horizon.
Mars is the fourth planet from the sun, named after the Roman God of War.
6,791 km (4,220 miles), about half that of Earth.
24 hours, 37 minutes, 23 seconds.
Carbon dioxide makes up 95.3% of the atmosphere compared to less than 1% on Earth, 2.7% nitrogen compared to 78% on Earth, and some argon and other trace gases.
Mars is a cold planet with a surface temperature ranging from minus 140 to 20 degrees Celsius (average -63), or on the old scale minus 220 to 70 degrees Fahrenheit (average -81).
Surface gravity is 3.72m/s2, or 0.38 of earth’s gravity.
Average Distance from Sun:
227.7 million km (141.5 million miles).
Olympus Mons at 15,850 metres (52,000 feet), dwarfing Earth’s highest mountain (Mt Everest) at 8,847 metres (29,028 feet).
Lowest Natural Point:
Valleris Marineris at 8 to 16km (5 to 10 miles) deep – deeper than the Grand Canyon.
Hellas Planitia at 9km (5.6 miles) deep
Tilt of Axis:
25 degrees (seasons similar to Earth)
Phobos – diameter 28km (17.4 miles); Deimos – diameter 16.1km (10 miles).
This stunning view of Mars was taken from Earth by the NASA Hubble Space Telescope on 10 March 1997, just before Mars opposition, when the Red Planet made one of its closest passes to the Earth (about 60 million miles or 100 million km).
2001 Mars Odyssey Obiter
NASA’s lost two Mars missions in 1999, but it is ready to try again. On 7 April, NASA launched its 2001 Mars Odyssey global orbiter and mapping satellite. The new probe will reach Mars on 24 October to begin a 600-day search for water that may be laying below the Martian surface. Locating underground water would tell scientists where future manned missions could land..
The instruments onboard the Odyssey will map the elemental composition of the Martian surface and determine the abundance of hydrogen in the shallow subsurface. Earlier signs of water detected by the Global Surveyor orbiter will be investigated fully, so scientists can determine without doubt, whether water exists or once existed on Mars.
The Odyssey will carry three science instruments. The Thermal Emission Imaging System (THEMIS) will map the mineralogy and morphology of the Martian surface. The Gamma Ray Spectrometer (GRS) will achieve global mapping of the elemental composition of the surface and determine the abundance of hydrogen in the shallow subsurface – the GRS is a rebuild of the instrument lost with the Mars Observer mission. The third science instrument, the Mars Radiation Environment Experiment (MARIE), will characterise aspects of the near-space radiation environment as related to the radiation-related risk to human explorers.
2001 Mars Odyssey will map minerals and elements, look for water, and study the radiation environment of Mars.
The search for life
Mars may once have been a very wet place. A host of clues remain from an earlier era, billions of years ago, hinting that the Red Planet was host to great rivers, lakes and perhaps even an ocean. But the clues are contradictory. The reason for the intense interest in Martian water is simple: without water, there can be no life as we know it. The search for life is really about the search for water. If it has been 3.5 billion years since liquid water was present on Mars, the chance of finding life there is remote. But if water is present on Mars now, however well hidden, life may be holding on in some protected niche. Based on what we have observed so far, Mars today is a frozen desert. It’s too cold for liquid water to exist on its surface and too cold to rain. The planet’s atmosphere is also too thin to permit any significant amount of snowfall. Even if some internal heat source warmed the planet up enough for ice to melt, it wouldn’t yield liquid water. The Martian atmosphere is so thin that even if the temperature rose above freezing, the ice would change to water vapour. Additionally, no evidence of carbonates has yet been found anywhere on the planet. Carbonates are minerals that form readily when liquid water reacts with carbon dioxide in the atmosphere. If Mars had abundant liquid water in the past, carbonates should be detectable in the Martian rock record. The Thermal Emission Spectrometer (TES) aboard the Mars Global Surveyor orbiter was designed to look for just such a signature, but has found none.
About the Author
Dr Mike Nichols is a plant research scientist at the Institute of Natural Resources, Massey University, Palmerston North, New Zealand.
For all your NASA headlines, NASA centers, information search, and frequently asked questions.
NASA outlines its Mars missions.
The latest news, images, and happenings on the future of Mars.
Everything you wanted to know about Mars.
The National Space Science Data Center (NSSDC) is NASA’s deep archive and general distribution center for lunar and planetary data. Includes Mars fact sheet and chronology. Ω
PH&G May/June 2001 / Issue 58