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The small town of Nobeyama sits among picturesque mountains 180 kilometres
west of Tokyo. In winter, when snow softens the jagged outline of the mountains,
Nobeyama becomes a ski resort popular with Tokyo ‘salarimen’. In the early
hours of Saturday morning, the peace of the place is shattered by the arrival
of scores of buses, which disgorge bleary-eyed office workers into the bitterly
cold air. Only on Sunday night, when the buses have headed back to the city,
does the place regain a semblance of normality.

But skiing is not Nobeyama’s sole attraction. The town is famous for
another, all-year-round, activity: astronomy. Day and night, the shiny white
dishes of the Nobeyama Radio Observatory patiently scan the skies. Nobeyama
is one of the world’s leading observatories – proof, if proof were needed,
that Japan really does support scientific research of the purest kind.

There are three major instruments at the site, and each is making important
contributions to our understanding of the Universe. Perhaps the most unusual
is the Nobeyama Radioheliograph, which is dedicated to studying the violent
convulsions of the surface of the Sun. With its 84 tiny dishes – each one
only 80 centimetres across – arranged in the shape of a giant ‘T’, the
instrument looks for all the world like a toy radio array. But the radioheliograph
is far from being a toy. ‘It’s the only instrument like it in the world,’
says Shinzo Enome, head of Nobeyama’s solar team.

National symbol

The radioheliograph started work in earnest last year. Its dishes observe
the Sun at a wavelength of around a centimetre and are capable of generating
pictures that are updated every second. The ever-changing image is on display
in the foyer of one of Nobeyama’s observatory buildings – the bloated disc
of the Sun quivers on a shoulder-high television monitor. The yellow sphere
is marred by ugly scars – sunspots, flares and prominences, some bigger
than the Earth itself. If you watch the picture long enough, these scars
eventually move out of sight as the Sun rotates, and others appear.

Solar astronomy is not a fashionable field, a fact which may go some
way to explaining the radioheliograph’s lack of competition. But it is no
accident that Japan is active in this area. ‘In Japan, radio astronomy got
its start with solar astronomy,’ says Enome. ‘The Sun, after all, is our
national symbol.’ Currently, the Nobeyama Radioheliograph is being used
in tandem with YOKHO, a Japanese X-ray satellite which was launched into
Earth orbit last year. By superimposing radio and X-ray images, Enome’s
team is trying to understand the violent processes that go on inside solar
flares.

Although the radioheliograph is Nobeyama’s newest and most unusual instrument,
the observatory also boasts an array of millimetre-wave radio dishes, one
of only four such arrays around the world. Millimetre waves are given out
by molecules floating in cold clouds of interstellar gas. They easily penetrate
thick swathes of dust, and so provide astronomers with a window into the
core of ‘molecular clouds’, where stars are born. Such regions are hidden
from the view of optical astronomers. Nobeyama has five dishes, each measuring
10 metres across, which work together to produce detailed pictures of regions
of star formation in our Galaxy and the explosive nuclei of ‘active’ galaxies
or AGNs. When it is used with Nobeyama’s 45-metre millimetre-wave dish –
the observatory’s third major instrument and the biggest millimetre-wave
dish in the world – the array has no rival.

But in radio astronomy, as in other fields of astronomy, the Japanese
have ambitious plans. In 1995, they plan to launch a radio dish with a diameter
of 8 metres into orbit. ‘It will be the first radio telescope ever to be
put in space,’ explains Masato Ishiguro, Nobeyama’s director. ‘It will also
be Japan’s first satellite telescope.’ The European Space Agency had its
own plan to orbit a radio dish, called QUASAT, but abandoned the idea, and
the Russians are unlikely to launch their 10-metre radio dish, dubbed RADIOASTRON,
until the end of the decade.

Until now, there has been no need to put a radio dish in space, because
radio waves easily penetrate the Earth’s atmosphere, unlike X-rays and some
ultraviolet rays, for instance. But in space, a radio dish will be able
to see finer detail in objects such as quasars and active galaxies using
a technique known as Very Long Baseline Interferometry (VLBI). To use the
technique, many radio telescopes scattered at different locations observe
the same object at precisely the same time. Signals recorded on magnetic
tapes at each telescope are then flown to a central computer for processing.
After considerable number crunching, an image is obtained which is as finely
detailed as one that would have been obtained by a single monstrous telescope
with an aperture as big as the distance between the two telescopes that
are farthest apart.

Until now, that distance has been limited by the size of the Earth.
But the Japanese radio dish will change that. Once it is launched – as part
of the VLBI Space Observatory Programme (VSOP) – its signals will be combined
with those from radio telescopes in Japan, Europe, Australia and the US,
to mimic a radio telescope between two and three times the size of the Earth.
It should be capable of seeing into the hearts of distant galaxies and quasars
where ‘supermassive’ black holes are thought to lurk.

Far-sighted ambitions

Japan’s radio astronomers have ambitious plans for the ground as well.
Astronomers at most of the world’s millimetre-wave observatories are planning
to boost the resolving power of their telescopes, or the amount of detail
they can see, by adding an extra dish – to make five, or in some cases,
six, dishes. American astronomers are even planning a giant millimetre-wave
array with 40 dishes, each measuring 8 metres across. But Ishiguro and his
colleagues intend to go further. They are hoping the government will provide
£200 million to build a millimetre-wave array – this time with an
astonishing 50 dishes, each with a diameter of 10 metres. ‘It will be the
ultimate ground-based millimetre-wave telescope,’ says Ishiguro.

If the government agrees to fund the Large Millimetre and Sub-millimetre
Array, it will have to be built abroad. Japan has no sites that are high
enough and dry enough – moisture in the atmosphere absorbs millimetre-wave
radiation and would prevent a giant telescope from working to full capacity.
Ishiguro’s team is looking at sites in China, Ha-waii and Chile.

If Hawaii is the choice, the new array will join Subaru, yet another
world-class Japanese observatory. Subaru will be an optical telescope with
a mirror 8 metres in diameter, almost as large as Keck, the most powerful
telescope in the world. It is the first major Japanese scientific facility
of any kind to be built on foreign soil, says Keiichi Kodaira, project scientist
on Subaru. Work on the £200 million telescope has begun on the summit
of Mauna Kea, part of the massive volcano which forms the main island of
Hawaii. When it is complete in 1999, it will clearly represent Japan’s bid
to join the leaders in world astronomy. The telescope will pioneer adaptive
optics – a computer-controlled system which will constantly flex the telescope’s
thin, lightweight mirror to cancel out the blurring effect of turbulence
in the atmosphere. No one has built anything like it yet, but if the system
works, the prize will be images which are as sharp as those seen from space,
yet have been snapped from beneath the blanket of the Earth’s atmosphere.

Kodaira, at least, is confident of success. He is already talking about
what may lie beyond Subaru. ‘Once the telescope is built on Mauna Kea, we
will have the infrastructure in place in Hawaii,’ he says. ‘It will be easier
to build another optical telescope. Perhaps another 8-metre. . .’

With Subaru, VSOP and the Large Millimetre & Sub-millimetre Array,
Japan is assembling formidable state-of-the-art observing instruments.
There is no doubt that the country is making a bid to become a major player
in the high-profile science of astrophysics. Not content with being a technological
superpower, Japan has designs on being a scientific superpower as well.
There are several reasons why Japan is making its move now. The most important
reason is clearly the success of the Japanese economy. Many people forget
that since the Second World War, Japan has been poor compared with the US
and Western Europe. ‘We scientists in Japan have always wished to realise
our dream,’ says Kodaira, ‘but until now our country’s financial situation
was not right.’

Only in recent years has Japan’s economy generated surplus cash for
luxuries. ‘Now, for the first time, society in Japan can afford to pay for
major scientific projects that do not bring back money to the state,’ says
Kodaira. ‘The US and major European countries reached this stage ahead of
Japan. They have been leading and carrying out scientific projects on behalf
of all human beings. Gradually, Japan is becoming prosperous enough that
it can afford to join this effort. ‘Before, we were supported by the foreign
astronomical community,’ says Kodaira. ‘Now at last we can build instruments
that others may use.’