Space Physics at Princeton

Welcome to Space Physics at Princeton

The Space Physics group in the Department of Astrophysical Sciences at Princeton University carries out a broad range of research spanning from the Sun and solar corona, through the solar wind and terrestrial and planetary magnetospheres, and encompassing the global heliosphere and its interaction with the local interstellar medium. We are the lead institution for numerous NASA Heliophysics missions and instruments that Prof. David J. McComas serves as the principal investigator for:

Interstellar Mapping and Acceleration Probe (IMAP) mission – just selected for development and launching in 2025 to explore the details of particle acceleration and the Sun’s interaction with the local interstellar medium;

Parker Solar Probe (PSP), Integrated Science investigation of the Sun (ISʘIS) instrument suite – launched 8/12/2018 to measure energetic particles as close in as 9 solar radii from the Sun’s surface;

Interstellar Boundary Explorer (IBEX) mission – launched in 2008 and still exploring the boundaries of our heliosphere and its interaction with the local interstellar medium;

New Horizons, Solar Wind Around Pluto (SWAP) instrument – launched in 2006, measured the plasma environments of Pluto and the jovian magnetosphere and continues to make unprecedented observations of interstellar pickup ions;

Advanced Composition Explorer (ACE), Solar Wind Electron Proton Alpha Monitor (SWEPAM) instrument – launched in 1997 and still providing solar wind data from the Sun-Earth Lagrangian point (L1);

Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) mission – returned the first stereo imaging of the Earth’s dynamic magnetosphere from 2008-2017;

Ulysses, Solar Wind Observations Over the Poles of the Sun (SWOOPS) instrument – discovered the three-dimensional structure of the solar wind from the first and only mission to fly over the poles of the Sun (operational from 1990 to 2009).



Research News

Publication: In Situ Observations of Interstellar Pickup Ions from 1 au to the Outer Heliosphere
May 9, 2022

Interstellar pickup ions are an ubiquitous and thermodynamically important component of the solar wind plasma in the heliosphere. These PUIs are born from the ionization of the interstellar neutral gas, consisting of hydrogen, helium, and trace amounts of heavier elements, in the solar wind as the heliosphere moves through the local…

Publication: Water-Group Pickup Ions From Europa-Genic Neutrals Orbiting Jupiter
May 4, 2022

Water-group gas continuously escapes from Jupiter's icy moons to form co-orbiting populations of particles or neutral toroidal clouds. These clouds provide insights into their source moons as they reveal loss processes and compositions of their parent bodies, alter local plasma composition, and act as sources and sinks for magnetospheric…

Publication: Closed Fluxtubes and Dispersive Proton Conics at Jupiter's Polar Cap
May 3, 2022

Two distinct proton populations are observed over Jupiter's southern polar cap: a ~1 keV core population and ~1-300 keV dispersive conic population at 6–7 RJ planetocentric distance. We find the 1 keV core protons are likely the seed population for the higher-energy dispersive conics, which are accelerated from
a distance of ∼3-5 RJ…

Publication: Sub-Alfvénic Solar Wind Observed by the Parker Solar Probe: Characterization of Turbulence, Anisotropy, Intermittency, and Switchback
Feb. 11, 2022

In the lower solar coronal regions where the magnetic field is dominant, the Alfvén speed is much higher than the wind speed. In contrast, the near-Earth solar wind is strongly super-Alfvénic, i.e., the wind speed greatly exceeds the Alfvén speed. The transition between these regimes is classically described as the "Alfvén point" but may in…

Publication: Clouds of Spacecraft Debris Liberated by Hypervelocity Dust Impacts on Parker Solar Probe
Jan. 24, 2022

Hypervelocity impacts on spacecraft surfaces produce a wide range of effects including transient plasma clouds, surface material ablation, and for some impacts, the liberation of spacecraft material as debris clouds. This study examines debris-producing impacts on the Parker Solar Probe spacecraft as it traverses the densest part of the…

Publication: Anomalous Cosmic-Ray Oxygen Observations into 0.1 au
Jan. 21, 2022

The Integrated Science Investigation of the Sun instrument suite onboard NASA's Parker Solar Probe mission continues to measure solar energetic particles and cosmic rays closer to the Sun than ever before. Here, we present the first observations of cosmic rays into 0.1 au (21.5 solar radii), focusing specifically on oxygen from ∼2018.7 to ∼2021…

Publication: Geometry of Magnetic Fluctuations near the Sun from the Parker Solar Probe
Dec. 22, 2021

Solar wind magnetic fluctuations exhibit anisotropy due to the presence of a mean magnetic field in the form of the Parker spiral. Close to the Sun, direct measurements were not available until the recently launched Parker Solar Probe (PSP) mission. The nature of the anisotropy and geometry of the magnetic fluctuations play a fundamental role…

Publication: Energy Dissipation in Turbulent Reconnection
Nov. 29, 2021

We study the nature of pressure-strain interaction at reconnection sites detected by NASA’s Magnetospheric Multiscale  (MMS) Mission. We employ data from a series of previously published case studies, including a large-scale reconnection event at the magnetopause, three small-scale reconnection events at the magnetosheath current sheets, and…

Professor David J. McComas awarded EGU's 2022 Hannes Alfvén Medal
Nov. 3, 2021

Congratulations to Princeton University Professor David McComas, he has been awarded the EGU's 2022, Hannes Alfvén Medal

The European Geosciences Union (EGU) has named the 50 recipients of next year’s Union Medals and Awards, Division Medals, and Division Outstanding Early Career Scientist Awards. These individuals are honored for…

Publication: Collisional Evolution of the Inner Zodiacal Cloud
Sept. 9, 2021

The zodiacal cloud is one of the largest structures in the solar system and strongly governed by meteoroid collisions near the Sun. Collisional erosion occurs throughout the zodiacal cloud, yet it is historically difficult to directly measure and has never been observed for discrete meteoroid streams. After six orbits with Parker Solar Probe …

Sun & Princeton Shield