2013 may be the year of the balloon. Just recently, Google unveiled an only-kind-of-crazy plan to use a network of balloons floating around the globe to provide wireless Internet to places that the world's existing network just doesn't reach. Here's another project with an even more daring use of balloons in mind. It's called HALO, for High Altitude Lensing Observatory. This one isn't about Internet. It's about telescopes.
HALO has little to do with Earth itself and everything to do with space. Gravity and Earth's atmosphere are the biggest barriers between the ground and space. It takes a lot of fuel and a lot of money--to launch a rocket, whether it's carrying people, a satellite, or a space telescope--out of the atmosphere. And because it costs a lot of money, it doesn't happen that often. So the scientists behind HALO, who want to chart more of outer space, plan to bypass the expense of a rocket launch by floating a telescope up, up, and up using a balloon.
According to The Atlantic, HALO physicist Richard Massey says "You can get 99 percent of the way into space with a very big balloon, about the size of a football stadium. You can get basically above almost all of the Earth's atmosphere...for about one percent of the cost of a satellite."
Of course, 99 percent of the way into space isn't quite all the way into space. The telescope won't make it up into a secure orbit. But it will ascend far enough into the atmosphere to take clear images of space, something even the most powerful telescopes on the ground can't do. And HALO has an ambitious goal even after it successfully gets a telescope 99 percent of the way into space: to map the dark matter in the universe. Which there's a lot of, we think.
How long could HALO's balloon-and-telescope rig hang out in the upper atmosphere, anyway? According to the project's white paper, quite a while--up to 100 days, in fact:
"With the development and testing of Ultra Long Duration Balloon (ULDB) ﬂights underway, the observation campaigns of the near future could be several months (up to ∼ 100 days) in duration for each launch, greatly increasing the data-gathering capabilities. Assuming a successful recovery of the payload, HALO could conduct an ∼ 100 day observing run (ﬂight) each year, with of order 1000 square degrees observed in each ﬂight."
These Ultra Long Duration Balloons are designed to reach heights of 30 kilometers, or more than 18.5 miles. But they're still a new technology--as of last year, NASA had run some test flights, but had yet to use them to carry scientific payloads. That means the HALO project could end up being a trailblazer in more ways than one.
Check out the rest of the paper for a ton more on the ULDB technology and the science of studying dark matter.