U professor uses NASA Hubble Telescope

Cati Vanden Breul

For the past 16 years, scientists around the world have used NASA’s Hubble Space Telescope to research the history of the universe. University astronomy professor Evan Skillman, who came to campus in 1989, is one of these researchers.

Describe your research with NASA.

I currently have one project where I’m the primary investigator. And last cycle, I was successful (in getting time on the telescope) with a primary investigator from Spain, and this cycle with a primary investigator from the University of Washington.

Both of these are so-called large projects; usually only four or five of these projects are given out per year, because they take up 5 to 10 percent of the time on the telescope. These are some of the largest projects attempted with the Hubble Telescope.

The key word between all of this is what we like to call astro-archeology. We look at very nearby galaxies, where we can construct a census of all the stars in a galaxy. We use those stars in the same way an archeologist digs down in the strata in the ground and looks back in time. We can use the stars to dig out the history of star formation.

One of the biggest questions right now in astronomy is how galaxies are formed and how they evolve.

What got you involved with NASA?

The Hubble Telescope was launched in 1990. When I was interviewing at the University, I was asked about my research and said I planned to use the Hubble for a number of proposals. It turns out I was lucky, I was able to follow up on that.

How does NASA choose which scientists may access the Hubble Telescope for research?

Every year, NASA puts out a call for proposals. In that call, they describe what instruments will be available and the status of the instruments. Essentially, they set out rules and everyone around the world writes up these proposals – generally about 10 pages or so. They can be put in by individuals, but are usually proposed by collective teams.

There are different types of proposals – small guest observer proposals and larger ambitious proposals where the data is thought to be of great value to the whole scientific community.

A couple of times I’ve served on the peer review committees that rank these proposals. It’s a difficult process because you’re saying no to five out of six when there are a lot of good proposals, and you’d like to say yes to five out of six. People from all over the world come to Baltimore, Md., and they spend two days together ranking all the proposals.

How many proposals are accepted each year?

It varies, but there are roughly 700 proposals made each year. Roughly about 100 of those proposals are given time on the telescope. The number of researchers differs because many of the proposals have 20 to 30 people from many different institutes.

I’ve been on both types: projects with three or four people, to large projects with 15 or so that I’m on currently.

What happens once your proposal is accepted?

Once the letter comes telling you that you’ve been awarded time on the Hubble Telescope, you then write descriptions on how you want the telescope to observe – where you want it to point, which instruments you want to use, how long you’d like it to observe – so the Space Telescope Science Institute (the institute that allocates time on the Hubble Telescope) can design those different computer prescriptions and schedule how to use the telescope (each year) in an optimal fashion.

Generally, you won’t know until one to two weeks ahead of time when your observations will be made. Once they’re complete, you’ll get an e-mail notification and then the data’s downloaded to an archive.

What is the University’s relationship with NASA?

The astronomy department at the University has been very successful at getting observation time within NASA facilities. In particular, Bob Gehrz, the chair of the department, was involved in building NASA’s Spitzer Telescope.

In a per-capita basis, we’re much more successful than other departments our size. We usually do better than average; we’re a very competitive group and we’ve historically done very well with these facilities.

Right now, NASA is coordinating a mission to repair the Hubble Telescope. What will this entail?

One part of a service mission is for things like going up and changing batteries, as mundane as that. But another part is to replace older instruments with newer instruments.

My research projects will really be able to take advantage of the two newer instruments they’re going to install on this mission. I’m not doing anything official on the service mission, but I definitely have science that’s waiting for these new instruments.