Carl A. Schmidt

Planetary Science

schmidtc @
Curriculum Vitae
PhD Thesis
Recent Conference Posters


Hi there! I'm a research scientist at the Boston University Center for Space Physics studying tenuous planetary atmospheres, also known as exospheres. Prior, I was a post-doc at CNRS/LATMOS in Paris, and a post-doc at University of Virginia. I'm live in Boston, along with my spouse Rachel, and our 2 year old kiddo, Wendy. This site contains scattered bits of information about my various projects.


I've been using a new instrument built here at Boston University called the Rapid Imaging Planetary Spectrograph (RIPS). RIPS is a visiting instrument that has split most of its time between the AEOS 3.7m at Haleakala and the Perkins 1.8m telescope at Lowell Observatory. It is currently located at the Dunn Solar Telescope, where we hope to develop a program for daytime Mercury observations to support BepiColombo. Travel bans surrounding COVID-19 have placed all RIPS observations on hold, but I keep busy working on the data already in-hand. Read more about RIPS...


Mercury's atmospheric content is comparable to the amount of air in a large building, spread over a whole planet. Still, its bright sodium and potassium emission lines are easily observable by small ground-based telescopes. Interpreting such observations and connecting them to the extensive MESSENGER dataset is a job for numerical models. I'm involved in several projects observing Mercury's thin atmosphere and simulating various ground- and space-based measurements. Read more about Mercury...


Jupiter's volcanic moon Io is my favorite object in our Solar System. It's actively changing before our eyes. Io's atmosphere partially collapses every 42 hours when the moon enters Jupiter's shadow, which allows for some nice observational experiments. Atmospheric escape can take the form of fast neutral jets, and any ionized gases form a wobbly doughnut orbiting Jupiter called the Io Plasma Torus. I've observed Io using Hubble's Cosmic Orgins Spectrograph and SOFIA, a telescope aboard a Boeing 747. I also lead some ground-based telescope campaigns for Juno mission support.


Cometary atmospheres are rich in complexity. Using an integral field spectrograph, I've studied the composition, structure, and dynamics of Comet C/2012 S1 (ISON), which, well. . . fell into the Sun. Puff. Then I worked with STEREO data to study striae formation in Comet C/2011 L4 (Pan-STARRS). After C/2020 F3 (NEOWISE) survived its July 2020 periapse, it was nice and bright. I'm now collaborating with PSI to model its coma, which looks like this.


Io's plasma torus collides with an adjacent moon, Europa. When the geometry allows, energetic neutral atoms escaping Io, also hit Europa painting its surface. It's not well known just how much material is transfered from one moon to the other, so I use HST observations and plasma torus measurements to estimate how much oxygen, sulfur and chlorine is transfered. Also, smaller ground-based telescopes can determine fraction of the sodium in Europa's atmosphere that is transferred from Io, rather than of native origins. Addressing this question ultimately helps resolve another: what's the salinity of Europa's subsurface ocean?


Earth's moon has a sodium atmosphere similar to Mercury's. During the LCROSS impact, colleagues at McDonald Observatory recorded a time series of a plume of sodium extending some 200 km above the impact site. RIPS also took some interesting data of the lunar atmosphere during its comissioning at Lowell Observatory that I'm reducing and simulating now. The Moon's escaping atmosphere has a cool interaction with the Earth's gravity near its New Moon phase. Some colleagues and I have used that feature to show that meteorite influx effectively regulates the Moon's atmospheric escape.