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Astronomer Henry Joy McCracken fears that recent events around the Mir space station and the Mars Pathfinder probe point to a closure of the 'final frontier'

Why have we still not walked on Mars?

Growing up, I always dreamed of Mars. I read with rapt wonder Ray Bradbury's stories of the red planet; with him I walked across ancient Martian flood plains which had not seen water for a millennium and gazed upon deserted, empty cities older than any on Earth. I soon discovered that we had just been to Mars, a few years earlier: the Viking landers had sent thousands of pictures back to blue-green Earth of a desolate place with a reddish-brown sky and rocks, rocks, rocks right to the horizon. Viking was just the start, I was sure: in 10 years men would walk on Mars (Richard Nixon had told us so, and I was young enough to trust him) and soon we would start to answer all the questions that Viking had raised. And there were many questions to answer - starting with the question of Martian life.

In August 1996 there was much excitement at the possible discovery of Martian microfossils in Antarctic met-eorites. Mars is certainly an attractive place to look for life; in the distant past it was much warmer and wetter than it is today and the ancient Martian flood plains would be excellent places to search for fossils. If life - even ancient life - was discovered on Mars, it would have immediate implications concerning the possible commonality of life in the Universe and the uniqueness of life on Earth.

We would also like to understand why and how the Martian climate changed from a temperate one which supported surface water to the parched, frozen one which exists today. And in a broader context, a thorough understanding of Martian geology would provide many insights into the formation of the solar system and the Earth itself. Mars is unaffected by many of the geological processes such as weathering and continental drift which on Earth quickly erase the geological record. The Martian highlands are old; and written in their hills and valleys is a lucid record of the formation of Earth and Mars, waiting to be read by any travellers that venture there.

Beyond these scientific objectives, another important fact should command our attention: apart from Earth, Mars is the only place in the solar system which can support a sustained and substantial human presence. There is water frozen beneath the Martian soil, and the Martian atmosphere and the length of the Martian day makes using this water to produce foodstuffs a viable proposition. Mars' lower gravity (one third of Earth's) would make long trips across Mars or to Martian orbit and beyond a trivial exercise - making Mars an excellent base for the exploration of the outer solar system. On a longer timescale, the transformation of the Martian climate into one less hostile to human life - one which is warmer and with a higher pressure and eventually a breathable atmosphere - is a process well within our knowledge of industrial chemistry and physics.

Early in July the Mars Pathfinder probe dropped out of the Martian sky, rolled to a stop and began to transmit information back to Earth. Was this the return to Mars that I had been waiting for since Viking, and a first step towards manned exploration of Mars and space beyond? The omens are not good. In the week of the Mars landing, Pathfinder shared the headlines with the troubled Mir space station, which a few weeks previously had suffered a near-fatal collision with a cargo ship full of rubbish. Since then, Mir has suffered mishap after mishap. Many leading scientists, such as Britain's Sir Martin Rees, have argued that Mir's troubles give us reason enough to halt manned exploration of space entirely. In every press conference and in every interview, people talk of the risks of space exploration, apparently without realising that exploration will always be risky.

However, it is not just Mir's problems that have disheartened me. Superficially, a greater contrast could not be imagined between Mir and the Mars landing: on one hand a 10-year-old semi-decrepit orbital shack, on the other the glittering, hyper-modern Mars Pathfinder Lander, which appears as comfortable on the frigid, arid Martian surface as it does in the balmy climate of Southern California. But beneath these differences both missions share a common aim: to explore space in the context of a social and economic environment which is hostile to exploration.

The success of the Mars Pathfinder is the success of sending a probe to Mars on the cheap, for the cost of a Hollywood movie - a somewhat doubtful achievement, especially if fulfilling this objective has an impact on the amount of useful science returned. The difficulties of the Mir station show how hard it is to adapt the human exploration of space to these new, more limited, economic horizons. There are some systems in an orbital station which must work, and which money must be spent on - like drains and air filtration.

The unfortunate fact is that rather than recent events presaging a manned trip to Mars, they are more likely to be the latest stage in the decline of human ambitions in space.

It is 40 years now since the first man-made object orbited the Earth. A commentator writing in the distant days of 1957 would have found it unbelievable if he had been told that by the end of the millennium the solar system would be largely unexplored (with the exception of the odd robot probe like Pathfinder), and that the human explor-ation of space would be limited to repair missions in low earth orbit along with (extremely boring) tests of endurance on a decade-old space station. Given the staggering advances made in those years in other areas such as computing, this state of affairs does indeed seem strange. But if we examine the motivations and reasons why we explore space, it is easy to see why after all this time we are still Earth-bound.

The ending of the Cold War had a profound impact on the human explor-ation of space. Up to that point, geo-political and military factors furnished the reasons for exploration. Space - 'the high frontier' - was an important military objective. It was also a means to display national superiority and exhibit a country's excellence in science and technology. These were the reasons the Americans competed so vigorously with the Soviet Union. And these were the reasons why the barren and airless Moon was such an attractive destination for manned space exploration. There is nothing on the Moon - no minerals, no water, no atmosphere. The Apollo ships were crewed by military men, not scientists - the first scientist did not travel to the moon until the last Apollo mission. The emphasis was placed firmly on reaching the Moon as an end in itself, a prestigious act of conquest, and scientific rewards, although they were great, were not the reason that the mission was funded.

Even in the midst of the Cold War, the manned exploration of space had begun to falter. After Apollo, Nixon was presented with an ambitious plan to put Americans on Mars by the middle of the 1980s. But faced with a multitude of economic and social problems at home and the Vietnam War, the pro-gramme was never funded. Then there was the Space Shuttle - presented as the next big thing in manned exploration, a reusable spacecraft. However, the Shuttle flew five times fewer missions than originally planned and its design was altered by the Department of Defence (who were paying) to allow the delivery of military payloads into low Earth orbit - severely limiting the Shuttle's mission capabilities. Today Space Shuttle astronauts seem more like repairmen than explorers, fixing the odd broken satellite or telescope here and there.

The public have also lost their enthusiasm if they have not become overtly cynical. Before the recent landing on Mars many expressed doubts about whether Pathfinder's intricate system of airbags and parachutes could land the craft safely on the surface of Mars - ignoring the fact that exploration is intimately linked to taking risks and attempting to achieve what has not been achieved before. After the successful landing, questions asked at the initial press conferences focused entirely on two minor problems afflicting the lander and rover, rather than the wealth of scientific data returning from Mars - all the more astonishing considering the fact that no real efforts had been made by NASA engineers at that stage to correct the difficulties.

What of the future? Throughout the press conferences officials continually stated the policy of 'faster, cheaper, better' which they believed the Pathfinder mission had vindicated. It is worthwhile looking at this new approach towards interplanetary missions a little more closely.

The Pathfinder mission cost approximately $200 million - a small sum compared with Viking, which was over a billion dollars. Does this mean that Pathfinder is 'better' than Viking? Hardly. The two missions had completely different objectives and were designed with a different set of spec-ifications. For example, Viking carried on board a $25 million biology lab designed to detect the presence of living organisms in the Martian soil - a complex enough task to carry out in an Earth-based laboratory but one which is infinitely more difficult to conduct in the remote deserts of Mars. The design of the Viking missions reflected the fact that they were the first Martian landers - the spacecraft systems had a high degree of redundancy and were tolerant to conditions much more extreme than those eventually encountered.

Pathfinder, by comparison, contained no life-science experiments and only a minimal science package. Its main mission objective was a technological one - to demonstrate how a small science package could be delivered to the Martian surface cheaply and safely. But if this is meant to be the wave of the future, it is a sign that we have given up on exploration. If we are to discover the true history of Mars, how its climate changed, where the water went to, if life ever existed there or if life exists there today, we will require more than robotic exploration. The missions of the 1970s showed that the surface of Mars is hostile to life; if there is life on Mars today it is probably far beneath ground, near volcanic vents, or in similarly inaccessible locations. These are precisely the sorts of locations which robotic probes would have the greatest difficulty reaching, but which would pose few difficulties to tool-wielding humans.

Human ingenuity and creativity can only be partially replicated on the surface of Mars by a robot probe 140 million miles from its controllers. Remarkably, there are no technological reasons preventing humans from travelling to Mars; many NASA design studies of the 1980s showed how the manned exploration of Mars could be carried out. The key aspect of the plans was that the fuel required for the return journey would be produced on the surface of Mars rather than transported from Earth. Adopting this strategy meant that Mars missions could be designed around existing spacecraft technologies.

Of course, travelling into space is a risky and extremely dangerous venture; that is why it is a frontier. It is also an activity where the potential rewards are very high. But like many frontiers, no specific, tangible and immediate economic benefits can be offered as an incentive to extend political vision beyond the surface of Earth.

This brings us to the real reasons why Mars is likely to remain unexplored. Society is dominated by economic calculation and an aversion to exploration - an aversion well demonstrated by the response to 'British-born' Michael Foale's presence on the Mir space station, where the main concern was to get him down again as if he was a child stuck up a tree. This safety-first attitude towards exploration is mirrored in our society's approach towards science in general. The human desire to question, to take risks and explore is challenged more and more often and with greater and greater vigour. The latest scientific discoveries are greeted not with acclaim and praise, but with a raised finger and questions: 'should we really be doing this? What are the consequences?', with little regard for the rewards they might bring. The demand for certainty and for freedom from risk and doubt is incompatible with the practice of science and is stifling it.

To venture into space we must be strong-willed and determined. We must be fully committed to its exploration and discovery; space permits no half measures and is unforgiving of mistakes. We will do a poor job of exploring our solar system and understanding the formation and history of Earth if we insist on doing it with automated probes and for the cost of a summertime blockbuster. Our picture of the rich geological history of the Martian flood plains and highlands will be an incomplete one if we are unwilling to make the perilous trip to Mars and look at the Martian hills through our own eyes, instead of the eyes of a television camera. We will be well rewarded for the risks we take.

Henry Joy McCracken is an astronomer at the University of Durham

Photos: http://www.marsweb.jpl.nasa.gov

Reproduced from LM issue 105, November 1997

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