Disturbing the Universe

David L Clements, science and science fiction

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EBEX observations end

The EBEX balloon CMB experiment, as discussed in this blog here, has completed its astronomical observations with the exhaustion of cryogens in the instrument. More details are available from the EBEX flight blog, but the end of observations, which came on 9th January, was as expected. I hope everything else has worked as well!

The payload is not back on the ground yet, as it is currently on the opposite side of Antarctica to the base at McMurdo Sound. They have to wait until January 17th for the balloon to finish its orbit of the continent before they can fire the pyrotechnics and bring the payload back down to Earth. After launch, that’s the riskiest stage for the hardware, but even if descent and landing go wrong, as they have done for other astronomical balloons (eg. in 2006 the BLAST telescope was dragged 200km, ended up in a crevasse, and was largely destroyed when the descent parachutes failed to detach after landing) hopefully the data will be safe.

SO keep those fingers crossed for a bit longer!

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EBEX launches

My colleague Andrew Jaffe brings the happy news that the EBEX balloon has successfully launched from Antarctica. EBEX is a next-generation CMB project, aimed to go beyond what has been achieved in space by Planck and WMAP by using much larger detector arrays to study polarisation in the microwave background. In the same way that the BOOMERANG and MAXIMA balloons set the scene for WMAP and Planck, EBEX and other dedicated polarisation experiments will set the scene for the next generation of CMB satellites currently being proposed, like COrE.

A balloon allows you to get above much of the atmosphere, so you can get some of the benefits of being in space, but you don’t have quite the same limitations on payload, power and proven reliability (and thus lack of up-to-date-ness) of the technologies used. EBEX can thus use arrays of thousands of detectors while Planck works with just a small number of individual pixels. The downside is that balloon flights, even long duration ones that circle Antarctica, last only a week or so, and the upper atmosphere is still not as good as space.

Ballooning is an odd scientific activity, with many of the hazards of a space mission, but with budgets similar to small ground-based projects. Things are not quite as pyrotechnic either. The launch of EBEX, shown here, is smooth and gentle compared to any space launch.

You can follow the EBEX flight, as the balloon orbits Antarctica, here.

Good luck to them!