I'm Josh Peek, an associate astronomer,
Head of the Data Science Mission Office at STScI,
and MAST Principal Investigator

I work on the diffuse universe and
improving scientific accessibility and productivity
with archives and data science methods.


We have moved from asking What is in the universe? to How did the those things come to be?
I try to answer this question by examining the diffuse phase of the universe. The story of every object in the universe can be simply told as "diffuse material became dense under the influence of gravity". My work aims to understand the flow of this diffuse material. To do this I use spectroscopic measurements of gas (chiefly the 21-cm line) as well as observations of the effects of dust obscuration. The spectroscopy helps me better understand the velocities of gas; the dust helps me understand where the enriched material is in our universe. I do this work with numerous collaborators, including members of the ISM*@ST Group


I lead the Galactic Arecibo L-Band Feed Array HI (GALFA-HI) survey of neutral hydrogen in the Galaxy in the 21-cm line, which covers 13,000 square degrees at 4' resolution. DR2 is now public!

Galactic Fibers

I explore and characterize diffuse, fibrous features in the neutral interstellar medium which we discovered with GALFA-HI. Their strongly magnetized character makes them powerful probes of the dynamic ISM and polarized CMB foregrounds.

Kinetic Tomography

I work on methods that combine data from 3D extinction maps with cubes from radio telescopes (CO, HI) as well as stellar absoption lines in pursuit of the velocity field Galaxy.

STScI Data Science Mission Office & MAST

At STScI I am the Head of the Data Science Mission Office and I am the PI of the Mikulski Archive for Space Telescopes.


STScI is a member institution of SDSS-V, the fifth generation Sloan Digital Sky Survey; I serve as our representative to the Advisory Council. One of STScI's contributions to SDSS will be SDSS-Legacy, which will serve as the final archive for all SDSS data in perpetuity. I co-lead this project with Adam Bolton; SDSS-Legacy is a cross-AURA project and will be shared between NOAO and STScI.


I lead the development of STScI's Archive and High Level Processing Partition concept for The Nancy Grace Roman Space Telescope. Roman, slated to launch in mid 2020s, will be a physics experiment, a survey, and an observatory, and our archive and science platform must provide for users who use it in all of these many ways.


Science is storytelling. I tell scientific stories and help others do the same.

The "Paper" of the Future

With Alyssa Goodman I wrote an article describing and showcasing what as possible in digital publishing in astronomy.


With Adrian Price-Whelan I developed methods for easily generating interactive figures for publications.

Public Lectures

I give award-winning public lectures!

Invisible Universe

In an Xperia Studio project I developed software for viewing the sky in wavelengths beyond the optical.

Interstellar Matter

I made a short film called Interstellar Matter based in part on our GALFA-HI data, which is an official selection of the 11th Annual Imagine Science Film Festival in New York.

Students & Postdocs

I have advised PhD students at Columbia University and Johns Hopkins University, where I am an Associate Research Scientist. I also supervise postdocs at JHU and STScI

Michael Busch

I advise Michael on his thesis, which focuses on hydroxyl (OH) as a probe of dark molecular gas in the Milky Way and nearby galaxies.

Dr. Claire Murray

I supervise Dr. Murray's postdoctoral work on Kinetic Tomography and phases of the interstellar medium. She is now a NSF Astromomy & Astrophysics Postdoctoral Fellow.

Dr. John Wu

I supervise Dr. Wu's postdoctoral work on galaxies and Neural Networks

Dr. Enrico Di Teodoro

I supervise Dr. Di Teodoro's postdoctoral work on Kinetic Tomography and QuaStar

Dr. Susan Clark

I co-advised Dr. Clark on her PhD work in neutral gas morphology in the ISM and magnetic fields. She is now a Hubble fellow at the IAS, and will be starting as an assistant professor in the Stanford Physics department in Fall 2021.

Kirill Tchernyshyov

I advised Dr. Tchernyshyov on his PhD work developing the field of kinetic tomography using applied mathematics methods. He is now a postdoc at University of Washington with Jessica Werk.

Dr. Yong Zheng

I co-advised Dr. Zheng on her PhD work in the circumgalactic medium and the disk-halo interface. She is now a Miller Fellow at UC Berkeley, and will be starting a faculty position Tsinghua University in Beijing in 2022.

About Me

I am married to the fabulous Katie Peek, and we reside in lovely Baltimore, Maryland. We have two sons, Maxwell and Ezra, born in 2012 and 2016. If you have questions about my name, you can check out my name FAQ. I'm a great resource to parents of children born with cleft lip / palate -- please don't hesitate to reach out. I enjoy a number of activities beyond astrophysics. I am the emeritus technical director for the small theater company elastic future, and have designed many sets for small theaters and spaces in Cambridge, Princeton, and San Francisco. I am a veteran burner, having attended Burning Man in 2001 and from 2006 to 2011 and in 2015. I enjoy rock climbing, and I boulder at Earth Treks Hampden, and I have bouldered in Yosemite, the Grand Tetons and around Berkeley. I have also been known to play Ultimate (frisbee) from time to time.