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Profile: Dr. Joanne 'Joe' Hill

Photo of Joanne 'Joe' Hill chilling out on the Chesapeake Bay.

Caption Me


Joanne "Joe" Hill was born in the UK, in Leicester, about 100 miles north of London. She grew up in a small village of 100 houses, and as a child she attended a small school with about 80 people. Later, she attended the University of Leicester because it had a strong space program. There, she was able to learn to build instrumentation that would be able to survive the space environment, which is the area of astronomy she most wanted to go into. "Ultimately, I wanted to be an astronaut. That was one of the drives behind it," she said.

Joe had considered pursuing her Ph.D. in a few places, but Leicester was the best option, because they had built ROSAT, and XMM was in progress. While she had wanted independence from her family while going to school, in the end, it made more sense for her to stay where she was. Her family gave her space to be independent and to do her own thing while she was at university.

She first became interested in astronomy by watching "Star Wars" when she was 6 years old. In fact, the GEMS T-shirt she wore during the interview features a modified quote from Star Wars: "Building polarimeters ain't like dusting crops, boy.") While she watched the Millennium Falcon jump through hyperspace, she wondered, "How can I get some of this? What am I going to do?" She is still hopeful that one day she'll be able to not only build the instrumentation, but take it into space herself, via traditional NASA routes or by commercial flights on suborbital spacecraft, as with Virgin Galactic.


From Leicester, she was invited to a post-doc program at Penn State in the United States, to work on sounding rockets. Joe says that the job at Penn State was her "five-star" job: it was building instrumentation, using charged coupled device (CCD) cameras, which related to her Ph.D. work, and putting them on sounding rockets, which was a link to NASA. She didn't know when she applied that there were plans to collaborate with University of Leicester to collaborate on a project, but that the money had not been awarded for it yet. Her interviewers already knew that if they won the money, that it would be used to get someone who already had links with the institution - meaning, a connection with University of Leicester. That first post-doc job worked out well for Joe, because she got to go home quite a bit.

Her thesis at University of Leicester was focused on CCD cameras and X-ray polarimetry. "It's funny how things go in a big circle," she said. While the CCDs for XMM were being made, some tiny CCDs with very small pixels were also constructed. "The idea was that if the pixels were small enough, then you could measure the track of the photoelectron that's ejected by the X-ray, and from that, you can determine the polarization." She worked for three years on that. "With some very good mirrors, you could make some measurements, but it's fairly difficult to stop enough X-rays to get the statistics you need." Now she's measuring the polarization with a gas detector.

"The concept of the detector we're using for GEMS is based on proportional counters, which when I did my CCD research, I thought proportional counters were basically old-school," Joe said. They were on ROSAT and on XTE, which were used a long time ago. Joe says that a gas detector offers the perfect medium, because the photoelectron track is longer, so it can be measured more easily. In silicon, the track is very small, and the pixels are not small enough to measure it.

Gamma ray bursts (GRBs) are another of Joe's interest areas. When she went to Penn State, her team worked on SWIFT, and that is how she came to collaborate with Goddard. The telescope looked at the afterglow of GRBs, and did measurements with the X-Ray Telescope (XRT). That is when she became interested in GRBs. "I mean, they're fantastic - these huge explosions halfway across the universe. How could you not be interested in these things?" GRBs are tough because they're short and come from any direction, but the wide field helps take care of that. An ideal GRB mission would feature a wide field-of-view Gamma-ray polarimeter to measure the prompt emission and have a detector behind the mirrors (like on GEMS), which would measure the polarization of the afterglow. Then there would be a polarization measurement across the lifetime of the GRB. But, Joe says, that is several generations away. Her hope is that polarimeters like the one she is currently helping to build will become part of the astrophysicist's toolbox, like the spectrometer and imager. Adding the polarimeter, she says, will give scientists an additional way to make measurements and constrain models.

Typical Day

The GEMS polarimeter team assembles the detector on the clean bench.

The GEMS polarimeter team assembles the detector on the clean bench.

A typical workday for Joe's project work changes depending on where the project stands in its lifetime. Days she is in the lab designing the detector that will go up on the mission are driven by what was found the previous day and the follow-ups needed for those findings. Once the detector is proven and the mission is won, the days are driven by the project schedule, its budget, and the launch date. This is where the GEMS mission stands right now. Every morning, Joe attends a "tag-up" meeting to decide what the day's activities will be, then everyone goes off to perform their individual tasks. There may be meetings with managers to figure out some of the design work that needs to be done. In the afternoon, typically Joe will work in the lab, testing the engineering test units (such as the sensitivity of GEMS) and ensuring that the functioning of the detector is fully understood.

Joe doesn't get as much hands-on time with the equipment as she used to. Now, she deals with schedules, PowerPoint presentations and meetings. She must explain to people how the detector is going to work, how it's been proven that it will work, how they know it's going to work while in space and how they know it's going to work when they put it all together. Then, there is a team of people who are doing those tests. It's a team effort, so the credit for the project is shared among all the members. Some days, though, she would still like to do something hands-on, just to remind herself that she can. "Let me just turn the dial for today, and then I'll go off to the meetings," she said.

Questions and Answers

Photo of Joe in an oxygen mask.

Joe in her oxygen mask at the National AeroSpace Training And Research (NASTAR) facility where she went through their sub-orbital scientist training.

What is one question in science would you like to see answered in your lifetime?
"It's not so much a question, but I would really like for man to get to Mars, or maybe to one of Mars' satellites. I am unusual in this division, I suppose, in that I really love the exploration of space. I know that a lot of the money gets taken away from analysis, research and building of instruments to do the manned exploration, but I think if we could get to Mars, or at least one of Mars' moons, that would answer the question 'Can we do it?'"

What is the one big dream you have, or the one thing that you would like to accomplish during your lifetime?
Her one big dream is to go into space with an instrument that she has helped build, and to be able to make the measurements. "That would be having my cake and eating it, for sure."

Who was your favorite teacher in school? What was this teacher like and how did he/she influence your life?
"I had awesome teachers throughout school, actually. One of the reasons that I've been able to continue working in science is that I had awesome teachers in school. So it's difficult to pick out one teacher. They all influenced what I did, and they were all very supportive, all the way through Ph.D. and everything else. I had one really 'mean' lecturer at the university. He used to yell at people. If they came in late to his lecture, he'd go nuts. He would just scream at them to leave. For the thesis for a Ph.D., one of the things you have to do is give a presentation of your thesis work to date. I used to hate giving presentations; I'd rather be knocked down by a bus. I mean, really, I was terrified. This guy was mad at me because I was supposed to be off doing research, and I had asked for my talk to be moved. So he made me go first, on the first day. I was terrified, and it was just a disaster. It was awful. So then I got threatened with being thrown out of the university, because this talk was so bad. He made me give a presentation every two weeks, for six months. But I'm able to give presentations now! I don't know if he was an 'awesome' teacher or if he was an evil teacher, but he was good." That's not really my favorite teacher, but the one that made one of the biggest impacts."

Publication Date: February, 2012