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JAPAN is lining up as the latest recruit to the international effort
to explore Mars in the 1990s. However, an international meeting, organised
by Japan’s Foreign Ministry and Education Ministry and held in Tokyo in
December, suggested that the country is still unsure of what its role will
be. And rivalry between Japan’s two main space agencies is likely to delay
the creation of a cohesive Mars programme.

The December meeting was held in response to a call by the American
Vice-President, Dan Quayle, for Japan to contribute to the Mars programme.
Since July, when President Bush called for a return to the Moon and eventually
to Mars, NASA has been working flat out to turn these goals into specific
proposals for projects before the political steam runs out. The policy emerging
is similar in many ways to that behind the Soviet Union’s Mars programme,
and it seems likely to be the start of an unprecedented period of cooperation
between the superpowers in space. The third science power in space, Europe,
is considering a complementary Mars programme, and Japan is anxious not
to be left out.

The US launched its last Mars missions, the Viking landers, in 1975.
They arrived a year later but found no evidence of life on the planet. This
is not surprising: apart from the thin atmosphere (around 6 millibars) and
cold, ranging from minus 130 Degree C at the poles to 17 Degree C at the
equator, the surface is bombarded with ultraviolet radiation which destroys
organic material.

But the question of whether life once existed on Mars, when the planet
was warmer and wetter than today, is still very much open. Geoffrey Briggs,
of NASA’s Office of Space Science and Applications, described this search
as ‘the focus of our plans for future missions’.

These missions, which will take place over the next 20 years, involve
sending robot spacecraft to Mars. By discovering more about the planet’s
geological history, which will give clues to its early climate, scientists
at NASA are hoping to find out why Mars developed in a different way to
Earth. Ironically, another reason for going to Mars is to confirm that it
is possible to study the planet from fragments found on Earth. These rare
meteorites, the ‘SNC’ class, have a very different composition from other
meteorites. They were apparently molten only a few hundred million years
ago, and so must have come from a planet with active volcanoes producing
lava flows. Mars is the most likely source. Finally, the robots will collect
information needed to send human beings to Mars, possibly in the 2020s.

American and Soviet scientists at the Tokyo meeting presented remarkably
similar sequences of missions to the planet, over similar timescales. ‘Both
sides have pretty much the same scientific goals and I think we agree generally
on the kinds of missions that will be needed,’ said Briggs.

The new American effort gets under way with the Mars Observer spacecraft,
due for launch in 1992. This will carry equipment to look at Mars globally.
Its instruments will measure the chemical composition of the surface and
temperatures in the atmosphere, and high-resolution cameras on board will
send back pictures of geological structures. It will also carry equipment
to communicate with later Soviet probes.

The next stage will be to send more landers, first as meteorological
and seismic observatories, and eventually as geological expeditions to bring
a sample of Mars back to Earth. ‘The history of Mars is written very clearly
in those samples,’ said Briggs. Laboratories on Earth could analyse such
material with an accuracy an order of magnitude greater than that achieved
by robots on Mars. Such a mission will not take place until 2001 at the
earliest.

The Soviet scientists at the meeting agreed with this timetable. They
are planning a mission called Mars 94, to be launched in 1994. Albert Galeev,
a director of the Space Research Institute in Moscow, said that the mission
would set up a network of orbiting spacecraft, balloons, surface penetrators
and small ground stations to collect data on the planet’s weather and composition.

The Mars 94 spacecraft will arrive at Mars in September 1995. The mother
spacecraft will be similar to the two the Soviet Union sent on their previous
Mars mission to rendezvous with Phobos, one of the planet’s two moons. The
orbiter will weigh 6 tonnes and carry 250 kilograms of scientific instruments,
designed to operate for one terrestrial year. These include a television
camera with a resolution of between 10 and 20 metres, an infrared and gamma-ray
spectrometer for studying the composition of the planet’s surface, and long-wave
radar capable of probing for water 100 metres below the surface. The spacecraft
will orbit Mars at an average altitude of 300 kilometres.

About one month after the spacecraft enters orbit around Mars, it will
release a balloon to roam over the surface for about two weeks, covering
some 2000 kilometres. It will float for six to eight hours a day, dropping
close to the surface during the evening, and will trail a guide-rope along
the ground. Both the guide rope and the gondola will contain instruments.

Next on the Soviet Union’s drawing board is a rover mission, possibly
to be scheduled for 1998. The size and design of the rover are still under
discussion. ‘The work is slowly proceeding, mostly at the level of studies,’
said Galeev.

Soviet engineers are developing two rovers. The larger is 2 metres long,
weighs 350 kilograms and runs on six wheels, each 60 centimetres in diameter.
The other is half its length, and weighs 70 kilograms including a 15-kilogram
load of scientific instruments. This rover, with a range of 200 kilometres
over 100 days, will have enough artificial intelligence to guide itself
away from danger independently of commands from Earth.

Even on the most optimistic schedule, the third stage, a mission to
bring back samples, will not fly until 2001. This seems to open the way
for a joint Soviet-American mission: ‘It is not a coincidence that the US
and USSR’s plans for a sample-return mission have the same date,’ said Galeev.

But like other parts of the Soviet space effort, the Mars programme
is fighting hard for its budget. ‘We hope to get funding for all three missions,
but we will see how it will happen,’ added Galeev.

Looking even further ahead, sending humans to Mars has been on NASA’s
agenda since July. Brigg’s team is paving the way for manned missions. ‘It
means now that the kind of missions that we will be undertaking in the future
will not be simply missions for science experiments but they will be acting
as precursors for the human landings later, both on the Moon and on Mars.’
This will make extra demands on the robotic programme. The robots will have
to select landing sites that are not only good for science, but safe for
humans.

Viking showed that the surface of Mars was very hazardous: ‘We tried
to choose the Viking landing sites for safety as well as science and we
found that there were many rocks on the surface that could certainly have
caused the Viking mission to have been unsuccessful,’ said Briggs.

Overall, the scientists agree that thetechnological challenge in getting
humans to Mars is much greater than sending humans to the Moon. They will
have to develop techniques to use the atmosphere of Mars to brake the spacecraft
when they reach the planet. A spacecraft equipped with a heat shield could
lose much of its velocity by sheer friction, as it enters the atmosphere
of Mars. This would reduce the need for fuel for retro-rockets.

The first human expedition will also have to navigate more accurately
than the Viking landers, which operated with uncertainties of hundreds of
kilometres. ‘In the case of the human landings, they will probablyhave to
land within say a hundred metresof a chosen target point.’ Ensuring suchaccuracy
so far from Earth will be very difficult.

The proposed mission to bring back samples will develop some of these
technologies. Perhaps the most difficult involve the control of equipment
over distances where a radio signal takes 40 minutes to make the round trip.
Even when humans are on Mars, they may still need robots to collect samples
far from base.

According to Ronald Greeley of the University of Arizona, researchers
still have only sketchy ideas about where humans will land on Mars. The
programme will have to include a survey of four types of site. In order
of complexity, these are sites for hard landers and penetrators, areas suitable
for survey by balloons, sites for mobile rovers and finally those for landings
by humans. ¿ìè¶ÌÊÓƵs in the US have recently expanded their ‘catalogue’
of possible landing sites on Mars to include all types of mission. It now
includes some 75 sites selected for scientific interest, said Greeley.

Even the best-surveyed area of Mars, the plain in the Northern hemisphere
where Viking craft landed, poses questions for scientists. For example,
they do not know the plain’s origin: is it lava flows or sedimentary rock,
laid down by a long-vanished ocean? Further exploration, using roving robots
which collect samples from different sites, will be even more difficult.
One promising site is the floor of an impact crater, 120 kilometres in diameter,
on the border between the volcanic Tharsis area and the ancient cratered
terrain. The idea is for the robot to take samples from the crater floor,
and the central peak, and then to travel to the ancient highlands. According
to Greeley, the rover would need to travel between 50 kilometres and 100
kilometres to have a good chance of collecting all the different types of
rocks the researchers want to study.

Choosing a landing site for human missions requires different criteria.
The first priority is safety, followed by the ability to tap local resources
such as water; scientific interest comes a poor third. Robot craft may need
to find deposits of ice for crews to tap, and extract water and oxygen from
it. On the other hand, sites with ice immediately below the surface may
not be safe for landing rockets or building bases. ‘Typically on Earth one
does not build in areas where there is permafrost,’ said Briggs.

At the moment, planners can be confident of only the first two types
of Mars mission. Choosing sites for rover missions, and certainly for human
landings, will need a lot more work.

The Mars Observer mission in 1992 will help to fill some of the gaps
in our knowledge. The orbiting spacecraft will carry a camera capable of
recording objects one metre in diameter on the surface. Even this may not
be enough to allow planners to specify sites for more complicated missions,
said Greeley.

Europe will play a much smaller role than the US and the Soviet Union
in the ‘invasion’ of Mars during the 1990s. Nevertheless, Agustin Chicarro,
of the European Space Agency, said the agency is studying several options
for its programme over the next 20 years. One option is for Europe to contribute
the robot arm for the Mars rover or sample-return mission. Another is to
set up a network of small stations on Mars, made up of saucer-shaped miniprobes
to rest on the surface and rocket-shaped projectiles to penetrate it. The
network would send back seismological and meteorological data over a martian
year.

Until recently, Japan’s role in the exploration of Mars was confined
to collecting meteorites of suspected martian origin from Antarctica. But
the Institute of Space and Astronomical Science (ISAS), one of the Ministry
of Education’s research efforts, is developing the technologies that missions
to Mars will need. On 23 January, the first Japanese spacecraft scheduled
to change orbits by boosting its speed during a ‘swing by’ of a planetary
body is due to blast off from the Tanegashima Space Centre in southern Japan.

This mission, MUSES-2, will carry the first Japanese craft to orbit
the Moon. It will launch into an elliptical orbit around the Earth, then
on 19 March change into a circular lunar orbit as it swings by theMoon,
which it will survey for a month. The ‘swing by’ technique, employed mostdramatically
by the Voyager missions, isessential for sending spacecraft on interplanetary
missions.

But ISAS is caught up in the main preoccupation of Japan’s space efforts:
constant bickering between different agencies over which is allowed to do
a particular job. This year, the institute won a victory over its rival,
the National Space Development Agency (NASDA), associated with the Ministry
of International Trade and Industry, when the government allowed it to develop
rockets of more than 1.4 metres in diameter. This had previously been NASDA’s
monopoly.

Significantly, NASDA, which already launches rockets capable of sending
sophisticated spacecraft to Mars, did not have a representative at the International
Mars Forum. ISAS’s present rocket, the M III, can carry at most 770 kilograms
into low Earth orbits. Its successor, the M V, will have more than twice
this much, enoughto carry out serious planetary missions. Ifall goes well,
the first M V launch will bein 1995.

The institute has three planetary missions on the drawing board. The
first, in 1996, aims to encounter Comet Wirtanen in the following year,
capture dust particles from its coma, and return them to Earth. This mission,
building on the successful encounter by two of ISAS’s spacecraft with Comet
Halley in 1986, is an attempt to achieve a world first: no one has yet analysed
material from a comet. Venus is the target of the next planned mission.
A spacecraft will approach the planet to within 300 kilometres and deploy
balloons in its atmosphere. The third mission is another lunar orbiter,
perhaps sending probes and penetrators to the Moon’s surface.

But Japan has no firm plans to send spacecraft to Mars, and Japanese
researchers are worried about being left out of what they see as an international
consensus. ‘I think Japan should have specific projects for Mars . . . we
shouldn’t just wait and see what happens, but get involved now,’ said Takafumi
Matsui, chairman of the International Mars Forum. Prime Minister Toshiki
Kaifu told the conference that: ‘It is Japan’s responsibility to join with
the United States, the Soviet Union and the nations of Europe to make a
major contribution to the development of international cooperation and to
further the exploration of Mars.’ The prime minister prudently avoided making
a commitment to specific missions.

The scientists are keen to win political support, but they are anxious
to point out that the exploration of Mars does not lend itself to quick
political fixes like Apollo. Briggs described it as ‘a more orderly programme’
than the race to the Moon. ‘The early push to get Apollo to the Moon led
to a less logical sequence of missions and so has required us to go back
at this point with a fairly simple lunar mission to provide the global context
that was not required during the Apollo missions. In the case of Mars, we
expect a much more orderly approach and we expect that it will be carried
out over about a 20-year period.’

‘There is no great rush, no race,’ added Briggs. ‘The plan will be to
take as long as needed to do the mission safely.’ The only worry is that
politicians the world over have much shorter horizons.