| Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites | |
| Names List: | TRACERS |
| Mission Type: | Heliophysics |
| Operator: | NASA |
| Spacecraft: | TRACERS |
| Spacecraft Type: | Orbiters (2) |
| Manufacturer: | Millennium Space Systems |
| Launch Date: | April 2025 (planned)[1] |
| Launch Rocket: | Falcon 9 Block 5 |
| Launch Contractor: | SpaceX |
| Orbit Reference: | Geocentric orbit |
| Orbit Regime: | Low Earth orbit Polar [2] |
| Orbit Altitude: | 600 km |
| Apsis: | gee |
| Insignia: | TRACERS Logo.svg |
| Insignia Caption: | TRACERS logo |
| Insignia Size: | 200px |
| Programme: | Small Explorer program (SMEX) |
| Previous Mission: | SMEX 16 |
| Next Mission: | SMEX 17 |
Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites (TRACERS) is a planned orbiter mission tasked to study the origins of the solar wind and how it affects Earth. TRACERS was proposed by Craig A. Kletzing at the University of Iowa who served as Principal Investigator until his death in 2023.[3] David M. Miles at the University of Iowa was named as Principal Investigator in his stead.[4] The TRACERS mission received US$115 million in funding from NASA.
TRACERS is a future mission by NASA that aims to answer long-standing questions critical to understanding the Sun-Earth System. TRACERS is a pair of identically instrumented spinning spacecraft that will study how the Sun's solar wind interacts with the Earth's magnetosphere. TRACERS was initially planned to be launched as a secondary mission to another orbiter named Polarimeter to Unify the Corona and Heliosphere (PUNCH). PUNCH will study the solar wind, a stream of charged particles emanating from the Sun, while TRACERS will study Earth's response.[5]
TRACERS will observe solar particles interacting with Earth's magnetic field at the northern magnetic cusp region. Here, the field lines guide particles from the boundary between Earth's magnetic field down into the atmosphere. In a process known as magnetic reconnection, the field lines violently reconfigure, sending particles out at speeds that can approach the speed of light. Some of these particles will be guided by the Earth's field into the region where TRACERS can observe them.[5] [6] TRACERS will study a longstanding question about where reconnection happens at the magnetopause and how the solar wind affects the place and timing, helping NASA better forecast the influx of energetic particles into Earth's magnetic field that has the potential to disrupt the power grid and satellite communications.[5] TRACERS and PUNCH will work well together with the other existing heliophysics spacecraft.[6]
On 20 June 2019, NASA announced that PUNCH and TRACERS were the winning candidates to become the next missions in the agency's Small Explorer program.[7] On 29 September 2023 NASA Launch Services Program selected SpaceX's Falcon 9 rocket to provide the launch service for TRACERS launch through the Venture-Class Acquisition of Dedicated and Rideshare (VADR) program.[8]
As of October 2023, TRACERS has a target launch readiness date of 13 April 2025.[9]
A technology demonstration, Magnetometers for Innovation and Capability (MAGIC), was added in 2020 with the goal to test prototype magnetic-field instruments.[10]