SpaceX’s Falcon 9 rocket lifted off from Vandenberg Space Force Base (VSFB) in California, carrying a series of investigative missions and technology demonstrators designed to enable new capabilities and reduce time to launch, with several of them fielded under various NASA programs.
NASA’s TRACERS mission and other payloads launched from Space Launch Complex 4 East (SLC-4E) on Wednesday morning at 11:13 AM PDT (18:13 UTC), within an approximately one-hour and 15-minute window. Tuesday’s attempt was scrubbed due to an issue with the Range.
Falcon 9 flew out on a southerly trajectory from Vandenberg, with the first stage touching down safely at Landing Zone 4 (LZ-4) as part of a return-to-launch-site landing.
This launch marked the 16th flight for Falcon 9 first stage B1081, which has launched various NASA missions to date, including Crew-7, PACE, and EarthCARE. This mission will also serve as the 90th Falcon 9 flight of 2025, as SpaceX continues to push toward achieving a set goal of 170 launches in a calendar year.
The primary payload for this launch is NASA’s Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites (TRACERS) mission, consisting of a pair of spacecraft built by Millennium Space Systems. Proposed by the University of Iowa, TRACERS will aim to study how the Earth’s magnetic field, or magnetosphere, protects the planet from the stream of charged particles emitted by the Sun, known as the solar wind.
TRACERS was originally slated to be launched as a secondary payload to another NASA mission, the Polarimeter to Unify the Corona and Heliosphere (PUNCH), as both missions were selected to be the next in the agency’s Small Explorer (SMEX) program. PUNCH was eventually remanifested as a secondary payload to the SPHEREx in-space observatory and successfully launched on a SpaceX Falcon 9 from Vandenberg on March 12.
The two TRACERS satellites — T1 and T2 — are constructed in identical fashion, each outfitted with a suite of instruments and thus taking full advantage of the ALTAIR satellite bus offered by Millennium Space Systems. The spacecraft will travel in tandem, one trailing slightly behind the other, in a circular Sun-synchronous orbit at an altitude of 590 km, with a degree of separation ranging from 75 to 900 km.
During the planned 12-month primary mission, the TRACERS duo will repeatedly transit the “cusp” — a region in space located near the north and south poles of Earth, where magnetic field lines act as a guide for solar particles to funnel through and collide with atmospheric gases. This is one of many phenomena that can be attributed to the creation of space weather, ranging from auroras to the disruption of communications systems.
One of the two TRACERS spacecraft undergoing integration and testing before launch. (Credit: Millenium Space Systems)
As the solar wind collides with Earth’s magnetosphere, the resulting interaction — known as magnetic reconnection — builds up energy that can cause magnetic field lines to violently reconfigure, sending particles away at high velocities that approach the speed of light. Some of these particles will then be guided by Earth’s magnetosphere into the cusp where TRACERS can observe them.
Magnetic reconnection is what TRACERS will study in order to answer a longstanding question about where it happens at the magnetopause, the boundary between Earth’s magnetosphere and the solar wind. The data gathered will help NASA better forecast and prepare for impacts of space weather events.
Joining the TRACERS satellites are five additional rideshare payloads, with three of them being NASA-funded. The first of these consists of the Athena Economical Payload Integration Cost (EPIC) small satellite developed at NASA’s Langley Research Center in Virginia. Additional funding for the mission was provided by the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Space Force (USSF)’s Space Systems Command (SSC), with mission management and integration services provided by SEOPS.
Athena EPIC is poised to serve as a pathfinder for space startup NovaWurks and its sensorcraft architecture, demonstrating a more innovative method for placing remote sensing instruments into orbit faster and more affordably. This approach enables the opportunity to learn from commercial best practices and implement an “all-of-government” approach.
York's BARD mission, 1 of 5 distinct missions we're launching this year, is ready for launch. BARD will flight-demonstrate PExT, an advanced communications technology developed in collaboration with @JHUAPL & NASA's SCaN Program. https://t.co/O1Wb1VPexU
— York Space Systems (@YorkSpaceSystem) May 14, 2025
Second is the Polylingual Experimental Terminal (PExT) demonstrator, which is managed by NASA’s Space Communications and Navigation (SCaN) program. Also known as “Bard,” the spacecraft will test an advanced communications terminal designed to enable real-time interaction between various government and commercial satellite relay networks — a first-of-its-kind capability as NASA looks to eventually shift toward a commercial satellite relay architecture.
Third on the manifest is the Relativistic Electron Atmospheric Loss (REAL) satellite, developed by Dartmouth College in New Hampshire under NASA’s CubeSat Launch Initiative. This payload will carry an instrument that is sensitive to the detection of high-energy protons and electrons, which will help characterize the loss of particles from Earth’s Van Allen radiation belts into the atmosphere.
Two other rideshare payloads that joined the flight log in the days leading up to launch include the LIDE transponder demonstrator developed by Tyvak and an Australian Skykraft spacecraft that will join an existing satellite constellation designed to provide real-time communications between air traffic controllers and aircraft pilots.
Artistic render of Skykraft’s air traffic management satellite constellation in Earth orbit. (Credit: Skykraft)
With the launch of TRACERS and its rideshares, NASA will once again expand its fleet of heliophysics spacecraft to complement the recently-launched PUNCH mission and the Parker Solar Probe. The agency is also anticipating the launch of the Interstellar Mapping and Acceleration Probe (IMAP) mission and other rideshares on a SpaceX Falcon 9 to the Sun-Earth L1 Lagrange point later this year, as part of an effort to study the heliosphere.
(Lead image: Falcon 9 B1081-16 launches the NASA TRACERS mission from SLC-4E at Vandenberg. Credit: SpaceX)
