A balloon designed to loft the world鈥檚 largest solar ultraviolet telescope high into the atmosphere has performed a successful 10-hour test flight. When the telescope makes its first science flight in 2009, it will boast vision more than two times sharper than any previous solar observatory, shedding light on what causes potentially dangerous outbursts from the Sun.
Ultraviolet observations cannot be done from the Earth鈥檚 surface, since the same UV-absorbing properties that make ozone so beneficial to life also block the light from reaching ground-based telescopes. So beginning in 1957, astronomers have sent UV observatories soaring above much of the atmosphere in balloons.
鈥淚t鈥檚 almost like observing from space,鈥� says Michael Kn枚lker, director of the High Altitude Observatory at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, US. 鈥淚f you fly in the Arctic or Antarctic, you don鈥檛 have any day and night interruptions, so you can observe for a long time 鈥� and it鈥檚 a lot cheaper than space.鈥�
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Kn枚lker is a principal investigator for the Sunrise project, a 1-metre solar UV telescope designed to fly in a balloon at an altitude of about 37 kilometres (120,000 feet). 鈥淭his would be the biggest aperture solar telescope ever flown,鈥� he told New 杏吧原创.
It would be able to image features on the Sun as small as 30 kilometres across, more than double the resolution of other instruments. That is thought to be the size of the smallest features so far observed on the Sun鈥檚 surface 鈥� bright structures called flux tubes.
Solar eruptions
These tubes are all over the Sun鈥檚 turbulent surface and each has a strong magnetic field. 鈥淭hese small structures are being thrown around, nudged together, ripped apart, pushed aside, pulled down [and] are basically pushed to the boundaries of these convective motion cells,鈥� says Kn枚lker.
鈥淭hey are key to the evolution of magnetic fields [that can lead to] solar eruptions of magnetised plasma that 鈥� when it reaches the Earth 鈥� can cause a geomagnetic storm and disrupt satellites,鈥� he adds. 鈥淲e are confident that if we can resolve, say 30 kilometres, we will be learning something very substantial [about the flux tubes].鈥�
The Sunrise telescope is expected to be ready to make its first scientific observations in mid-2009. Then, organisers hope to take advantage of the 鈥榤idnight Sun鈥� to send it on a flight around the Arctic lasting as long as two weeks (though this is dependent on Russia relaxing its current ban on US balloons flying in its airspace).
Gondola ride
After that, the telescope may make other Arctic flights, launching from Kiruna, Sweden, as well as lifting off from McMurdo research station in Antarctica.
But team members must first test out the design and stability of the system as it swivels and shakes in the wind. So on 3 October, they sent a 26-centimetre telescope on a 10-hour balloon flight from New Mexico, US.
The flight will help engineers finesse the design of the telescope鈥檚 support structure, or gondola, which uses a motor drive and a precise guiding system to keep the telescope pointed in the right direction.
The project, estimated to cost about $85 million, is an international collaboration between institutions and companies in Germany, Spain, Sweden and the US.
