Durham, Toronto and Princeton Universities have teamed up with NASA and the
Canadian Space Agency to build a new kind of astronomical telescope.
SuperBIT flies above 99.5% of the Earth's atmosphere, carried by a helium
balloon the size of a football stadium. The telescope will make its
operational debut next April and when deployed should obtain high-resolution
images rivaling those of the Hubble Space Telescope. Mohamed Shaaban, a
Ph.D. student at the University of Toronto, will describe SuperBIT in his
talk today (Wednesday 21 July) at the online RAS National Astronomy Meeting
(NAM 2021).
Light from a distant galaxy can travel for billions of years to reach our
telescopes. In the final fraction of a second, the light has to pass through
the Earth's swirling, turbulent atmosphere. Our view of the universe becomes
blurred. Observatories on the ground are built at high altitude sites to
overcome some of this, but until now only placing a telescope in space
escapes the effect of the atmosphere.
The Superpressure Balloon-borne Imaging Telescope (or SuperBIT) has a 0.5
meter diameter mirror and is carried to 40km altitude by a helium balloon
with a volume of 532,000 cubic meters, about the size of a football stadium.
Its final test flight in 2019 demonstrated extraordinary pointing stability,
with variation of less than one thirty-six thousandth of a degree for more
than an hour. This should enable a telescope to obtain images as sharp as
those from the Hubble Space Telescope.
Nobody has done this before, not only because it is exceedingly difficult,
but also because balloons could stay aloft for only a few nights: too short
for an ambitious experiment. However, NASA recently developed
'superpressure' balloons able to contain helium for months. SuperBIT is
scheduled to launch on the next long duration balloon, from Wanaka, New
Zealand, in April. Carried by seasonally stable winds, it will
circumnavigate the Earth several times—imaging the sky all night, then using
solar panels to recharge its batteries during the day.
With a budget for construction and operation for the first telescope of US$5
million (£3.62 million), SuperBIT cost almost 1000 times less than a similar
satellite. Not only are balloons cheaper than rocket fuel, but the ability
to return the payload to Earth and relaunch it means that its design has
been tweaked and improved over several test flights. Satellites must work
first time, so typically have (phenomenally expensive) redundancy, and
decade-old technology that had to be space-qualified by the previous
mission. Modern digital cameras improve every year—so the development team
bought the cutting-edge camera for SuperBIT's latest test flight a few weeks
before launch. This space telescope will continue to be upgradable, or have
new instruments on every future flight.
In the longer term, the Hubble Space Telescope will not be repaired again
when it inevitably fails. For 20 years after that, ESA/NASA missions will
enable imaging only at infrared wavelengths (like the James Webb Space
Telescope due to launch this autumn), or a single optical band (like the
Euclid observatory due to launch next year).
By then SuperBIT will be the only facility in the world capable of
high-resolution multicolour optical and ultraviolet observations. The team
already has funding to design an upgrade from SuperBIT's 0.5 meter aperture
telescope to 1.5 meters (the maximum carrying capacity of the balloon is a
telescope with a mirror about 2 meters across). Boosting light gathering
power tenfold, combined with its wider angle lens and more megapixels, will
make this larger instrument even better than Hubble. The cheap cost even
makes it possible to have a fleet of space telescopes offering time to
astronomers around the world.
"New balloon technology makes visiting space cheap, easy, and
environmentally friendly," said Shaaban. "SuperBIT can be continually
reconfigured and upgraded, but its first mission will watch the largest
particle accelerators in the Universe: collisions between clusters of
galaxies."
The science goal for the 2022 flight is to measure the properties of dark
matter particles. Although dark matter is invisible, astronomers map the way
it bends rays of light, a technique known as gravitational lensing. SuperBIT
will test whether dark matter slows down during collisions. No particle
colliders on Earth can accelerate dark matter, but this is a key signature
predicted by theories that might explain recent observations of weirdly
behaving muons.
"Cavemen could smash rocks together, to see what they're made of," added
Prof. Richard Massey of Durham University. "SuperBIT is looking for the
crunch of dark matter. It's the same experiment, you just need a space
telescope to see it."
More information:
Details about SuperBIT:
sites.physics.utoronto.ca/bit