Enabling much cheaper access to space than rocket launches, the balloon will carry the Superpressure Balloon-borne Imaging Telescope (Superbit) above 99.5% of the Earth’s atmosphere.
The telescope is a collaboration between Durham University, NASA, the Canadian Space Agency, and Toronto and Princeton universities. It will make its operational debut next April, and its developers claim it will obtain high-resolution images rivalling those from the Hubble Space Telescope.
Light from a distant galaxy can travel towards Earth unimpeded for billions of years, before hitting the planet’s turbulent atmosphere and giving us a blurred view of the universe. Observatories on the ground are built at high altitudes to overcome some of this, but until now only placing a telescope in space escapes the effect of the atmosphere.
Now, the project will use a ‘superpressure’ balloon developed by NASA to carry the telescope to an altitude of 40km. Previous balloons could only stay aloft for a few nights, but the NASA balloon can contain helium for months.
Made of many separate panels of thin film attached to 'tendons' that run from top to bottom, the balloon takes the shape of a squashed sphere when at float altitude. It is filled with enough helium to lift the system, and to pressurise the balloon when it reaches the desired height.
Superbit will launch on a long duration balloon flight from Wanaka, New Zealand, in April 2022. Carried by seasonally stable winds, it will circumnavigate the Earth several times, imaging the sky using a 0.5m diameter mirror at night, then using solar panels to recharge its batteries during the day.
Crucially, the telescope cost almost 1,000 times less than an equivalent satellite. Not only are balloons cheaper than rocket fuel, but the ability to return the payload to Earth and relaunch it means the design has been tweaked and improved over several test flights – unlike satellites, which must work first time, and typically have very expensive redundancy.
A final test flight in 2019 demonstrated “extraordinary” pointing stability, a Durham announcement said, “sufficient to thread a needle 1km away, and to hold it for an hour”. Such stability will let the telescope obtain images as sharp as those from Hubble, the announcement said.
University of Toronto PhD student Mohamed Shaaban, who will be presenting the research at the Royal Astronomical Society’s National Astronomy Meeting today (21 July), said: “New balloon technology makes visiting space cheap, easy and environmentally friendly. As well as building a space telescope, our team has successfully tested all sorts of electronic and mechanical systems that could be used in future satellites.”
Peering into the dark
The science goal for the 2022 mission is to measure the properties of dark matter particles. Although dark matter is invisible, astronomers map it by 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 such behaviour has been predicted.
Professor Richard Massey, from Durham’s department of physics, said: “Cavemen could smash rocks together to see what they’re made of. We’re going to use Superbit to look for the ‘crunch’ of dark matter.”
Long term, the team hopes the balloon-launched Superbit telescope will be even better than Hubble. The iconic space telescope will not be repaired again when it fails, and other telescopes will only offer infrared or single optical band imaging – unlike Superbit, which offers multicolour optical and ultraviolet observations. The team already has funding to design a wider-angle upgrade, and they hope it could form the basis for a ‘fleet’ of space telescopes accessible to astronomers around the world.
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