The four crew members are true renaissance men and women. Given the nature of their mission—exploration far from home—all are cross-trained in several disciplines. At heart, though, they are a crew of two field
scientists and two mechanics. A biogeochemist and a geologist will complement a pilot who is also a competent flight engineer. The last crew member, a jack-of-all-trades, is primarily a flight engineer, but can also provide common forms of medical treatment and understands the broad means and objectives of the scientific investigations. This person backs up all the specialists in their functions, and provides one more—he or she will be the mission commander.
On board the
Beagle
, four men and women prepare themselves for a journey that will take them to another world and return them home in the span of about two and one half years—about the same amount of time it took explorers centuries before to circumnavigate the globe. Miles distant from their small ship, more than a million people camped around Cape Canaveral gaze in anticipation as the countdown clock approaches zero. The lower-stage engines of the booster erupt, pouring out a sea of flame. A cheer louder than any this country has heard in years sweeps the crowd as the Ares 3 lifts off the pad. The rocket accelerates, propelling the upper stage and its payload through the atmosphere. The upper stage fires its own engines and breaks away, driving the hab to trans-Mars cruise velocity. Four humans are on their way to Mars.
The pilot of the hab directs it to pull away from the burnt-out upper stage of the booster, releasing it on a tether 330 meters long as it goes. A small rocket engine on the hab fires, causing the tethered combination of hab and upper stage to now revolve at two revolutions per minute. This generates enough centrifugal force to provide the astronauts in the hab with artificial gravity en route to Mars equal to that found naturally on the Red Planet.
APRIL 2008
On the 180th day of flight, the hab arrives at Mars. The vehicle drops the tether and upper stage, and then aerobrakes into orbit. The crew intends to set the
Beagle
down at the landing site hard by the ERV that flew out to Mars in 2005. A radio beacon in the Ares 1 ERV, detailed photos and maps of the landing site, a landing pad radar transponder, and the crew’
s expert handling of the ship virtually guarantee a precision landing. In the unlikely event that the
Beagle
misses the landing site, the crew has three backup options available. In the first place, they have on board the hab a fueled, pressurized rover boasting a oneway range of nearly 1,000 kilometers. So long as they’re within that distance of the landing site, the crew can still get to their ERV by driving overland. If some disaster causes the
Beagle
to miss the mark by more than a thousand kilometers, the second backup can be brought into play. This is the ERV launched by Ares 2, which, since it was launched on a slower trajectory than the
Beagle
, is now following the crew to Mars. Even if the crew lands the hab on the wrong side of the planet, this second ERV can be maneuvered to land near them. Finally, as a third-level backup, the crew arrives at Mars with sufficient supplies for three years—if worse came to worst, the four could just tough it out on Mars until additional supplies and another ERV could be sent out in 2009.
The landing, however, is right on target. Though they have studied the landing site in detail, seen it from images captured by rovers and relayed to Earth, nothing can prepare the crew for the sight of the Martian landscape stretching before them. The soils are rust colored, littered with sharp-edged rocks, large and small. In the distance are small hills and dunes. The landscape is akin to the deserts of America’s southwest, save for the skies, which are a ruddy, salmon color. There’s an immense amount to be done just after touchdown, but they take the moment to gaze out at Mars, to savor the fact that no creature with eyes to see has ever gazed out on this vista in the four-billion-year history of Mars and Earth.
With the
Beagle
safely down at the landing site, the Ares 2 ERV lands some 800 kilometers away, where it begins the process of filling itself with propellant. It will be used as the ERV for the second human expedition, which will arrive at its site in Hab 2 in 2009, along with another ERV that will open up Mars landing site number three. As the missions proceed, a network of exploratory bases will eventually be established, turning large areas of Mars into human territory.
The crew of the
Beagle
will spend five hundred days on the Martian surface. Unlike conventional Mars mission plans based upon orbiting mother ships with
small landing parties, Mars Direct places all the crew on the surface of Mars where they can explore and learn how to ll arrive the Martian environment. No one has been left in orbit, vulnerable to the hazards of cosmic rays and zero-gravity living. Instead, the entire crew will have available to them the natural gravity and protection against cosmic rays and solar radiation afforded by the Martian environment, so there is no strong motive for a quick departure. For a crew left in orbit during a conventional mission, there’s little to do but soak up cosmic rays, and that tends to create a strong incentive to limit the time allowed for surface exploration, generally to thirty days or so. This leads to spectacularly inefficient missions. After all, if it takes a year and a half for a round trip to Mars, a stay of only thirty days is rather unrewarding. Worse yet, the rush to get back home forces conventional missions to follow trajectories that require far more propellant. But that extra propellant alone won’t get a spacecraft back to Earth directly. Because Earth and Mars are constantly changing their positions relative to one another, “quick return” flight plan trajectories have to get a gravitational boost by swinging past Venus—where the Sun’s radiation is twice that at Earth.
Even with such a substantial amount of surface time, the crew’s days will be filled with projects that will vastly expand our knowledge of the planet and pave the way toward future exploration and, eventually, human facilities and settlements. There will be the geologic characterization of Mars, which will begin to tell us the story of Mars’ past climatic history, how and when it lost its warm and wet climate, key clues to reviving Mars and perhaps saving the Earth. Geologic investigations will also include searches for useful mineral and other resources. Above all, astronauts will seek out easily extractable deposits of water ice or, better yet, subsurface bodies of geothermally heated water. Ice or water is key, because once water is found, it will free future Mars missions from the need to import hydrogen from Earth for rocket propellant production, and will enable large-scale greenhouse agriculture to occur once a permanent Mars base is established. Experimentation with agriculture is another item high on the priority list, and an inflatable greenhouse will be brought along for this purpose. The ar
ea of exploration that will seize the attention of the people of Earth, though, will be the astronauts’ search for Martian life.
Images of Mars taken from orbit show dry riverbeds, indicating that Mars once had flowing liquid water on its surface—in other words, that it was once a place potentially friendly to life. The best geologic evidence indicates that this warm and wet period of Mars’ history lasted through the first billion years of its existence as a planet, a period considerably longer than it took life to appear on Earth. Current theories of life hold that the evolution of life from nonliving matter is a lawful, natural process occurring with high probability whenever and wherever conditions are favorable. If this is true, if the theories are indeed correct, then chances are life should have evolved on Mars. It may still lurk somewhere on the planet, or it may be extinct. Either way, the discovery of Martian life, living or fossilized, would virtually prove that life abounds in the universe, and that the billions of stars scintillating in a clear, dark night sky mark the home solar systems of living worlds too numerous to count, harboring species and civilizations too diverse to catalogue. On the other hand, if we find that Mars never produced any life, despite its once clement climate, it would mean that the evolution of life is a process dependent upon freak chance. We could be virtually alone in the universe.
Given the importance of the question, the search for life past or present will be intensive, for there are manylanerent places to look. There are dry riverbeds and dry lake beds that may have been the last redoubts of the retreating Martian biosphere, and thus promising places to look for fossils. Ice sheets covering the planet’s poles may hold well-preserved frozen remains of actual organisms, if there were any. There is a high probability that subsurface ground water, geologically heated, may exist on Mars. In such environments living organisms may yet survive. What a find such organisms would be, for they are sure to be very different from anything that has evolved on Earth. In studying them, we would discover what is incidental to Earth life, and what is fundamental to the very nature of life itself. The results could lead to breakthroughs in medicine, genetic engineering, and all the biological and biochemical sciences.
The search for life and resources will necessarily involve a bit more than ambling a few meters along the Martian landscape and drilling a hole or two. The first explorers to Mars will have to range across the Martian landscape, beyond the horizon of their small base. The pressurized ground rover, which provides a shirtsleeve environment for astronauts, will allow the astronauts to explore far and wide on week-long sorties from their base. The rover burns methane/oxygen fuel, the same as the ERV. Ten percent of the stockpile of the methane/oxygen fuel produced by the ERV chemical plant will be allocated to support ground exploration. With this much fuel to run their car, the astronauts will be able to explore a vast area around their base, racking up over 24,000 kilometers on the vehicle odometer before the end of the first mission. As the rover crew travels, they will leave behind them small remote-controlled robots which will allow the base crew, and those of us on Earth, to continue to explore a multitude of sites via television.
The enormous amount of exploring the astronauts will undertake will necessarily result in a staggering amount of information, all of it new, undoubtedly unique and certainly more than any one crew member could digest. Each astronaut will confer regularly with panels of the world’s top experts in his or her assigned fields, creating a massive flow of information between Earth and Mars. Of course, crew members will also send and receive personal messages, but because there is a time lag in the transmission of radio waves between Mars and Earth, they will have to put up with delays of up to forty minutes before they get their answer. That will be troublesome for people accustomed to telephone conversations, but no problem at all for those who still know how to write a decent letter.
SEPTEMBER 2009
At the end of a year and a half on the Martian surface, the astronauts clamber aboard the ERV and blast off to receive a heroes’ welcome on Earth some six months later. They leave behind Mars Base 1, with the
Beagle
hab, a rover, a greenhouse, power and chemical plants, a stockpile of methane/oxygen fuel, and nearly all of their scientific instruments. In May 2010, shortly after the first crew reaches Earth, a second crew arrives at M
ars in Hab 2 and lands at Mars Base 2. The crew of the second mission will spend most of their time exploring the territory around their own site, but they will probably drive over at some point and revisit the old
Beagle
at Mars Base 1, not just for sentimental reasons, but to continue necessary scientific investigations in that region.
Thus every two years, as shown in
Figure 1.2
, two Ares boosters will blast off the Cape, one delivering a hab to a previously prepared site, the other an Earth return vehicle to open up a new region of the Red Planet to a visit by the next mission. Two boosters every two years: That̻s an average launch rate of just one launch per year—12 percent of our heavy-lift launch capability—to support a continuing and expanding program of human Mars exploration. This is certainly affordable and thus sustainable. As an added bonus, the same Ares launch vehicles, habs, and Earth return vehicles (fitted with only one propulsion stage) used in the Mars Direct plan can also be used to build and sustain lunar bases. While Moon bases are most emphatically not needed to support Mars exploration, they are of considerable value in themselves, most notably as sites for superb astronomical observatories. By using common transportation hardware for both lunar and Mars exploration, the Mars Direct approach will save tens of billions of dollars in development costs.
Mars Direct is not without risk. The consequences of extended exposure to Mars’ gravity—38 percent that of Earth—are unknown. However, experience with the more severe deconditioning of astronauts in orbiting zero-gravity facilities indicates that most of the ill effects are temporary. Then there is space radiation, which on the six-month transit trajectories necessitated by current or near-term propulsion technology will give the astronauts doses sufficient to cause an additional 0.5 to 1 percent probability of a fatal cancer at some point later in life. This is nothing to scoff at, but those of us who stay home all face a 20 percent risk of fatal cancer anyway.
The Martian environment itself may hold some surprises, yet the 1970s vintage
Viking
landers, which were designed for ninety days of operation, functioned without hindrance on the Martian surface for four years, unaffected by cold, wind, or dust. The biggest mission risk arises from possible failures in critical mechanical or electrical systems. Multiple backups for all important systems can minimize the risk, as can the presence of two ace mechanics during the mission. Anyway you slice it, though, going to Mars the first time will involve a certain level of risk. This will be true whether we make the attempt with Mars Direct in 2007 or leave it for another generation to try. Nothing great has ever been accomplished without risk. Nothing great has ever been accomplished without courage.