Most ambitious project yet for European Southern Observatory will be large enough to search for life on other planets.
Shortly after lunch on Thursday afternoon the silence of the Atacama desert in
Chile will be rudely broken by the dull crack of dynamite sending a rush of mountain rock skywards.
The
explosion, planned for 2pm local time (7pm BST), marks the start of a
months-long project to lop the top off the 3,000m-high Cerro Armazones.
Once the dust has settled and the rubble has been cleared, the mountain
will be smaller, flatter, and ready to host the largest optical and
infra-red telescope in the world.
The
European Extremely Large Telescope,
or E-ELT, will serve astronomers and cosmologists for generations to
come. Size, as the name implies, matters. Some 2,500 tonnes of steel
rigging are on order to hold a primary mirror nearly 40m wide. That is
large enough to see the faintest light from the earliest stars, and pick
up signs of life on planets far beyond our solar system.
"Today we cannot even imagine what will be discovered with this facility," programme manager
Roberto Tamai told the Guardian from his office in the Chilean desert. "I feel excited. We are opening a highway for the future knowledge of
astronomy."
The
telescope is the latest and most ambitious project for the European
Southern Observatory (ESO), a multinational organisation of which
Britain is a leading member. The UK has invested £88m in the E-ELT and
will have a significant role in the construction and operation of the
telescope, and the advanced instruments it will carry.
But first
the jagged peak of Cerro Armazones must be tamed. The mountaintop needs
to be broken apart and bulldozed to a plateau large and strong enough to
hold the enormous observatory. Perched on top of the reshaped mountain,
the €1.1bn (£879m) E-ELT will have near-perfect conditions for
observing the heavens.
Cerro Armazones is not the first mountain to be decapitated in the area. Twenty kilometres away across the B710,
which cuts a lonely route through the desert, is Cerro Paranal. Engineers from the ESO cut that peak down to size some years back to build another facility, the
Very Large Telescope (VLT). They will use the same procedure this time: blast and clear, blast and clear.
In
the coming months, mMore than half a million tonnes of rock will be
removed from Cerro Armazones, leaving it 18 metres shorter. Scientists
and engineers will watch the first blast on Cerro Armazones from the
safety of Paranal. The event will be filmed and
streamed live on the web from 6pm to 8pm BST, though images from cameras closer to the action may take a day or two to release.
Work
in the desert can be a hard slog. The humidity is down to about 10%,
making the air extraordinarily dry. The hotel at Paranal has a swimming
pool in the lobby and for very good reason.
"You can swim in it if
you like, but the point is to keep the humidity at a bearable level. If
you sleep for eight hours in 10% humidity, you are almost dead by the
time you wake up because you breathe out so much moisture," said Joe
Liske, an astronomer at the
E-ELT science office.
The
low humidity is not the only problem for the 100 or so ESO staff at
Paranal. Dust gets everywhere, in your shoes, your glasses, your car.
The desert hues, shades of pinky, orangey brown, are monotonous. People
come to crave a view of the sea, and the green of plants, entirely
absent from the desert. Then there are those missing loved ones back
home. "There's a lot of sacrifice. Your private life goes ga-ga," said
Tamai.
The E-ELT will take a decade to build. The telescope's huge
mirror is too large to make from one piece of glass, so engineers will
combine 798 smaller hexagonal mirrors, each of which can be moved
independently. The E-ELT has a system called adaptive optics that can
shift the mirrors in real time to counteract the blurring effects of the
atmosphere. "We need to be able to adjust each one to get the perfect
shape for the primary mirror, and that has to happen at all times to get
the best possible image quality," Liske said.
When the telescope
is operational, around 2024, astronomers will point it at Earth-like
planets orbiting sun-like stars in far away solar systems. So far,
scientists have made only the most rudimentary measurements of these
planets, but E-ELT could change all that. "We want to study the
atmospheres of planets that are just the right distance from their stars
that life might form on their surfaces. The goal is to try to say
whether life might exist on some of these planets," said Liske.
A
planet's atmosphere can hold numerous signs of life. The E-ELT will look
for infrared signatures of methane, released by much of life on Earth,
and other gases such as oxygen and carbon dioxide. The telescope could
detect direct signs of life, such as chlorophyll found in vegetation.
The telescope will have many more uses though, many are not yet
apparent. In 2011, scientists shared a Nobel prize for work on
supernovae, or exploded stars, that revealed how fast the universe is
expanding.
Isobel Hook, an astrophysicist at Oxford University who works on E-ELT, hopes to use the telescope to observe more distant supernovae.
"We'll
be able to see supernovae much further away, and so map out the
expansion of the universe to much earlier times," she said. "The E-ELT
is really the next big step for astronomy everywhere."
