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_acronym_list.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