TRACERS (TS) Data https://spdf.gsfc.nasa.gov/pub/data/tracers/ This directory gathers the data from the Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites (TRACERS) mission https://tracers.physics.uiowa.edu/, see also https://science.nasa.gov/mission/tracers/. TRACERS is a NASA mission led by the University of Iowa to answer long-standing questions key to understanding space weather, particularly how the Sun transfers energy, mass, and momentum to near-Earth space. TRACERS consists of two identical satellites that orbit Earth in tandem (one following the other). TRACERS 1&2 were launched on 2025 July 23, and are now in a ~590 km, Sun synchronous low Earth orbit. Each orbit takes about 90 minutes. Their separation in time along the orbit varies from 10 to 120s (75 to 900 km along track). Both TRACERS 1&2 carry 6 identical in-situ instruments. Due to the failure of the battery on TRACERS 1 near the start of commissioning, it can only take data on the Sun-lite side of the Earth. Currently all instruments on both satellites except Analyzer of Cusp Electrons (ACE) and MAGnetometers for Innovation and Capability (MAGIC) on TRACERS 1 are taking data. The cadence of TRACERS data is broken into two categories: Region of Interest (ROI) high-cadence data for about 8 to 16 minutes of data during a 90-minute orbit, and Back Orbit (BOR) low-cadence data collected outside the ROI. Note on ROI: for TRACERS-2 there is one prime science ROI per orbit targeting the southern cusp (usually ~6.5-8 minutes long), and up to one other-science ROI per orbit in the northern hemisphere (usually ~3-8 minutes long). TRACERS-1 only does the cusp ROIs, and the length of those can vary more, due to the operational constraints on that spacecraft. Acronym list for TRACERS https://spdf.gsfc.nasa.gov/pub/data/tracers/documents/tracers_acronyms.html https://tracers.physics.uiowa.edu/tracers-science-data-acronym-list. Mission Description Publications TRACERS mission paper: Miles, D.M., Kletzing, C.A., Fuselier, S.A. et al. The Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites (TRACERS) Mission. Space Sci Rev 221, 61 (2025). https://doi.org/10.1007/s11214-025-01184-4. Gives the science objectives: descriptions of the spacecraft and instrumentation. TRACERS mission design: Petrinec, S.M., Kletzing, C.A., Miles, D.M. et al. The Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites (TRACERS) Mission Design. Space Sci Rev 221, 60 (2025). https://doi.org/10.1007/s11214-025-01185-3. Includes discussion on ROI. Back orbit: Dorelli, J.C., Friedel, R., Chen, LJ. et al. Science Opportunities in the TRACERS Back Orbit: Ionospheric Signatures of Magnetotail Reconnection. Space Sci Rev 222, 22 (2026). https://doi.org/10.1007/s11214-026-01270-1. Discussion of back orbit and back orbit science. Science Operations Center (SOC): Christopher, I.W., Kletzing, C.A., Crawford, D. et al. The Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites (TRACERS) Science Operations Center. Space Sci Rev 221, 74 (2025). https://doi.org/10.1007/s11214-025-01199-x, Processing of L0 & L1 and SPICE kernels, ensure data quality and distribution of L2. Appendix has definitions of all coordinate systems used. Instrument Publications Analyzer of Cusp Electrons (ACE): Halekas, J.S., Hansen, C., Ruhunusiri, S. et al. The TRACERS Analyzer for Cusp Electrons. Space Sci Rev 221, 21 (2025). https://doi.org/10.1007/s11214-025-01147-9. Electron measurements from 20 eV to 13.5 keV, with angular resolution of 10x7 degrees, cadence of 50 ms to provide sub-kilometer resolution in the cusp in ROI and 6.4 s in back orbit BOR. Analyzer of Cusp Ions (ACI): Fuselier, S.A., Freeman, M.A., Kletzing, C.A. et al. The Analyzer for Cusp Ions (ACI) on the TRACERS Mission. Space Sci Rev 221, 30 (2025). https://doi.org/10.1007/s11214-025-01154-w. Ion measurements from 8 to 28k eV, 47 logarithmic-spaced energy steps, angular resolution of 22.5x6 degrees, cadence of 312 ms in ROI, and in BOR only 1 out 128 energy sweeps are saved so cadence of ~ 40 s. Electric Fields Instrument (EFI): Bonnell, J.W., Ludlam, M., Slagle, A. et al. The Electric Field Instrument (EFI) for the TRACERS Mission. Space Sci Rev 221, 80 (2025). https://doi.org/10.1007/s11214-025-01202-5. Electric field measurements with a sampling rate for EDC of 128 samples/s (ROI), 8 samples/s (BOR), EAC 2048 samples/s (ROI), electric field high frequency (EHF) 20e6 samples/s (ROI). For EAC and EHF the sampling rate is the same as the ROI, but the cadence is 16 s and 2048 s respectively. Magnetometer (MAG): Strangeway, R.J., Cao, H., Orrill, E. et al. The TRACERS Fluxgate Magnetometer (MAG). Space Sci Rev 221, 84 (2025). https://doi.org/10.1007/s11214-025-01212-3. The 3-axis vector fluxgate magnetometer has a sampling rate of 128 samples/s in the ROI and 16 samples/s in the BOR. MAGnetometers for Innovation and Capability (MAGIC): Miles, D.M., Lasko, A., Bounds, S. et al. The MAGnetometers for Innovation and Capability (MAGIC) Technology Demonstration Payload. Space Sci Rev 221, 64 (2025). https://doi.org/10.1007/s11214-025-01191-5. The 3-axis vector fluxgate magnetometer has a sampling rate of 128 samples/s in the ROI and 16 samples/s in the BOR. Magnetic Search Coil (MSC): Hospodarsky, G.B., Carton, A.J., Dvorsky, R.T. et al. The Magnetic Search Coil (MSC) on the TRACERS Mission. Space Sci Rev 221, 72 (2025). https://doi.org/10.1007/s11214-025-01200-7. Three axis search coil magnetic field measurements at 2048 samples/s (~1 to ~ 1kHz) in the ROI and in BAC a subset at the same sampling rate is returned. Overview of Data The data are stored and distributed at the University of Iowa TRACERS website https://tracers.physics.uiowa.edu/l2-public-data-products and https://tracers.physics.uiowa.edu/magic-0 and mirrored at NASA https://spdf.gsfc.nasa.gov/pub/data/tracers/. Note the filenames of the data on SPDF have been renamed (i.e., ts1_ > tracers1_, t2_ > tracers2_). Datasets are broken into daily files; except for MAG and MAGIC whose files are further broken into ROI and BOR. ROI and BOR data are combined in the other instrument data files. Data Directories on the SPDF (in alphabetical order) * /documents/ - Documents (e.g., data management plans and user guides) for TRACERS mission and instruments. * /tracers /tracers1/ace_cusp-electrons/l2/def_diff-en-flux/ -electron differential energy flux * /tracers/tracers1/aci_cusp-ions/l2/ipd_ion-dist/ -ion distributions * /tracers/tracers1/efi_elec-fields/l2/eac_elec-ac/ -AC electric field * /tracers/tracers1/efi_elec-fields/l2/edc_elec-dc/ -DC-electric field * /tracers/tracers1/mag_fluxgate/l2/bdc_mag-dc-bor/ -DC MAG during BOR * /tracers/tracers1/mag_fluxgate/l2/bdc_mag-dc-roi/ -DC MAG during ROI * /tracers/tracers1/magic_mag-innov/l2/bor/- DC MAG Innovation during BOR * /tracers/tracers1/magic_mag-innov/l2/roi/- DC MAG Innovation during ROI * /tracers/tracers1/msc_mag_searchcoil/l2/bac_mag-ac/ -SEARCH COIL time series data * /tracers2/ace_cusp-electrons/l2/def_diff-en-flux/ -electron differential energy flux * /tracers2/aci_cusp-ions/l2/ipd_ion-dist/- ion distributions * /tracers/tracers2/efi_elec-fields/l2/eac_elec-ac/ -AC electric field * /tracers/tracers2/efi_elec-fields/l2/edc_elec-dc/ DC-electric field * /tracers/tracers2/mag_fluxgate/l2/bdc_mag-dc-bor/ -DC MAG during BOR * /tracers/tracers2/mag_fluxgate/l2/bdc_mag-dc-roi/ -DC MAG during ROI * /tracers/tracers2/magic_mag-innov/l2/bor/ -DC MAG Innovation during BOR * /tracers/tracers2/magic_mag-innov/l2/roi/ - DC MAG Innovation during ROI * /tracers/tracers2/msc_mag_searchcoil/l2/bac_mag-ac/ -SEARCH COIL time series data Miscellaneous/Rules of the Road While there are multiple levels of science data, only Level 2 and above are served at CDAWeb. When there are multiple versions of data for the same time interval, only the latest version is shown in the public SPDF archive and CDAWeb server. A full list of TRACERS datasets will also be available from the Heliophysics Data Portal https://heliophysicsdata.gsfc.nasa.gov/ and SPASE registry https://spase-metadata.org/. When using the TRACERS data from the SPDF archive, please acknowledge the TRACERS mission team, instrument team, and NASA Space Physics Data Facility for making the data publicly available. Here is an example acknowledgement: We thank the TRACERS mission team, led by the University of Iowa and supported by NASA's Heliophysics Explorers Program, for the data used in this study, which were obtained from the SPDF archive. See TRACERS rules of use https://tracers.physics.uiowa.edu/rules-use. Data Contacts: TRACERS Science Operation Team (SOT): tracers-sot@uiowa.edu NASA/GSFC SPDF: Scott A Boardsen scott.a.boardsen@nasa.gov NASA/GSFC SPDF: Lan Jian lan.jian@nasa.gov SPDF Support: NASA-SPDF-Support@nasa.onmicrosoft.com Last updated on 2026 March 25