This week the NuSTAR News update is a report on the yearly proposal cycle to figure out what the telescope will observe in the coming observing cycle (which runs June-May every year). For a small mission only planning to observe the high energy sky for two years at launch, NuSTAR is now into its 12th “General Observer” Cycle with a healthy oversubscription rate (meaning that there are many more requests to use NuSTAR than the available time). It’s also useful to think a bit about what that means and how it affects the flow of funding (as well as the NASA budget) and how this impacts astronomers (especially early career astronomers).

Read more: Funding astronomy (in the U.S.)

How does it work?

In a nutshell, the telescope teams (be it flagship observatories like JWST and Hubble or more humble Explorers programs like NuSTAR) operate the telescopes for NASA. The initial science program is executed by the Science Team for the mission during a baseline mission usually lasting a couple of years. After this, the team essentially turns the telescope over to the scientific community to determine how to best use the telescope. This is done through a “Call for Proposals” through an omnibus funding tool called the Research Opportunities in Space and Earth Science (ROSES). This a huge bill that covers everything from technology development and lab science to data analysis from NASA missions.

Prior to 2026, individual missions had a NASA Research Announcement (I won’t use the acronym) detailing the available observing program. In 2026 this has now been merged into a single “combined” announcement. For NuSTAR, the proposal deadline is usually around the end of January every year. Astronomers (either professional or amateur) from almost anywhere on the planet write up a four page proposal to observe either a single targets or samples of targets with the telescope. This can usually take a few weeks of work to make sure (i) that the science that you want do is compelling and that the source(s) you want to observe can help you address the science; (ii) that these sources haven’t already been observed and, if so, that the science that you want to do can’t be done solely with the data already in the can; and (iii) that you’re asking for the right amount of observing time with the telescope.

For NuSTAR, the proposals then go through a technical evaluation by the Science Operations Center (SOC), which is mostly checking to see if what the proposers have asked for is physically possible rather than assessing the science. The Guest Observer Facility at NASA’s High Energy Science ARChive (where all NuSTAR data are eventually made publicly available) puts together a review panel. Each panel consists of a blend of scientists with relevant backgrounds and usually spanning career stages from junior postdocs to senior/retired scientists. The panel then assesses all of the proposals and assigns them a ranking based on how compelling the science is and how well justified the observing time is. After roughly a week of discussion(usually in March/April), the panel decides on a final observing program, which is then sent to the NuSTAR SOC to execute starting June 1.

What does that have to do with funding?

For all NASA projects where the lead scientist is based in the U.S., getting an approved proposal brings with it the opportunity to secure research funding to actually do the science, write the paper, and get the paper published. (Aside: Some friends outside of science are rather scandalized by the fact that scientists pay to publish their results rather than journals paying them for the content…but that’s another story /Aside). The amount of funding varies widely based on the size of the mission; in the past, I’ve heard tell of astronomers effectively getting enough money from a single Hubble proposal to pay their own summer salary, a grad student, and a postdoc. While this may be apocryphal (and is certainly not as true today as it was 15 years ago), it brings up the key point that in astronomy the key way that astronomers secure funding for their junior colleagues is to get observing proposals like this accepted. For small missions like NuSTAR, the amount of funding available gets spreads over the approved programs where the lead scientist is eligible to accept funding, and can pay for about half a year of a graduate student or a postdoc.

For all missions, the operating budget paid out by NASA includes this funding. In most cases this is a significant portion of the overall yearly spend that flows directly to the U.S. scientific community. So when we hear about drastic funding cuts to operating missions, it usually comes out of the general observer pool of funds first (because you still have to pay the handful of people running the mission) and directly affects the scientific community.

It’s still very hard to get funding. Even in its 12th year operating as a general observatory, NuSTAR is over subscribed by at least 3x (and over 5x if you think about the highly competitive and compelling time domain science that NuSTAR does). Hubble and JWST frequently have over-subscription rates over 6. Which tells us that the community is strong and that we’re still only funding a fraction of the science that we could do with the observing fleet.