NASA and SpaceX successfully launched the agency’s Interstellar Mapping and Acceleration Probe (IMAP) from Florida on Wednesday morning. Joining IMAP on its way to Lagrange Point 1 are two additional rideshare payloads: NOAA’s Space Weather Follow On-Lagrange 1 (SWFO-L1) and the joint NASA/University of Illinois Carruthers Geocorona Observatory.
Liftoff took place on Wednesday, Sept. 24, at 7:30 AM EDT (11:30 UTC) from Launch Complex 39A (LC-39A) at the Kennedy Space Center in Florida. Weather was 85% favorable for launch during an instantaneous launch window, with the primary concern being the cumulus cloud rule.
Falcon booster B1096 supported this mission, flying for the second time after previously launching the KF-01 mission for Amazon’s Kuiper internet constellation in July.
After flying due east out of the Cape, B1096 reentered Earth’s atmosphere, performed an entry burn to slow its descent, and finally landed safely atop one of SpaceX’s east coast droneships, Just Read the Instructions, which was stationed downrange in the Atlantic.
Following stage separation, the second stage, IMAP, and the rideshare payloads continued flying into an interplanetary transfer orbit.
After being successfully deployed from the second stage, IMAP, SWFO-L1, and the Carruthers Geocorona Observatory are now flying to the Sun-Earth Lagrange Point 1 (L1), which is located between the Sun and our planet, approximately 1.5 million km away from Earth.
This launch marked the 121st Falcon 9 mission of 2025, and the 539th overall. Furthermore, this launch was the 220th orbital launch attempt worldwide in 2025.
IMAP
Selected by NASA for development by a team from Princeton University in 2018, IMAP will serve as the fifth mission under NASA’s Solar Terrestrial Probes program. Using a suite of 10 science instruments, IMAP will map and investigate the heliosphere, the vast bubble created by the Sun’s wind that completely encloses our solar system.
IMAP is expected to answer four critical questions that have plagued heliophysics for decades: what are the properties of the local interstellar medium; how do magnetic fields interact from the Sun through the local interstellar medium; how do the solar wind and interstellar medium interact through the boundaries of our heliosphere; and how are particles accelerated to high energies throughout the solar system?
Artist’s impression of the IMAP spacecraft in orbit. (Credit: NASA/Princeton University/Patrick McPike)
What’s more, IMAP is expected to accomplish four main science goals during its three to five-year mission at L1. First, IMAP will improve our understanding of the composition and properties of the local interstellar medium.
Next, the mission will advance scientists’ understanding of the temporal and spatial evolution of the region where solar wind and the interstellar medium interact. Third, IMAP will identify and advance the understanding of processes derived from interactions between the Sun’s magnetic field and the local interstellar medium. Lastly, IMAP will increase our understanding of particle acceleration processes around the Sun and within the heliosphere.
IMAP is relatively small, massing 900 kg and measuring just 2.4 m in diameter and 0.9 m in height. Despite this small size, IMAP’s engineers and scientists implemented 10 scientific instruments on the spacecraft, all of which enable IMAP to view our solar system across different wavelengths and energies.
Three imaging instruments are featured on IMAP. The IMAP-Lo imager is a single-pixel neutral atom imager that will measure and map low-energy, energetic neutral atoms (ENA) created where solar wind and the interstellar medium meet. IMAP-Hi features two single-pixel high-energy imagers that will measure and map medium-energy ENAs located near the edge of the heliosphere. The last of the imagers is IMAP-Ultra, which will map and measure the highest-energy ENAs near the edge of the heliosphere.
IMAP during vibration testing ahead of launch. (Credit: NASA/Johns Hopkins APL/Princeton/Ed Whitman)
Next is IMAP’s magnetometer (MAG), which utilizes two identical triaxial fluxgate magnetometers mounted on a 2.5 m boom arm to measure the interplanetary magnetic field generated by the Sun. The Solar Wind and Pickup Ions (SWAPI) instrument will measure ions within solar wind and particles that enter the solar system from beyond the heliosphere.
The High-Energy Ion Telescope (HIT) will utilize silicon solid-state detectors to investigate high-energy ions emitted from the solar wind and deep space. The Global Solar Wind Structure (GLOWS) instrument, a non-imaging single-pixel photometer, will study the characteristics and evolution of an ultraviolet glow produced by solar wind as it traverses the solar system.
The Solar Wind Electron (SWE) instrument will identify and measure electrons embedded within solar wind and their distributions within the wind. The Compact Dual Ion Composition Experiment (CoDICE) utilizes two electrostatic analyzers to measure the mass and charge of ions emitted from solar wind and interstellar space.
The 10th and final IMAP instrument is the Interstellar Dust Experiment (IDEX), which is a high-resolution dust analyzer that will examine the characteristics of interplanetary and interstellar dust particles within the solar system. These characteristics include the elemental compositions, velocities, and mass distributions of the dust particles.
IMAP is powered by solar panels and will communicate with Earth via NASA’s Deep Space Network, which will relay data to IMAP’s Mission Operation Center (MOC) at the Johns Hopkins University Applied Physics Laboratory (APL) in Maryland. After deployment from Falcon 9, IMAP will travel through interplanetary space for 108 days before arriving at L1. IMAP’s unique position at L1 will allow it to provide scientists with up to 30 minutes of “warning” before a solar storm impacts Earth.
APL provides project management during the mission, with Dr. David McComas of Princeton University serving as IMAP’s principal investigator.
SWFO-L1
One of the rideshare payloads joining IMAP on its journey to L1 is the National Oceanic and Atmospheric Administration’s (NOAA) SWFO-L1 spacecraft. Much like IMAP, SWFO-L1 will heavily study the Sun and its activity, with SWFO-L1’s nonstop data stream providing scientists with ample warning time ahead of large-scale solar storms that may damage Earth and space-based infrastructure.
SWFO-L1 will utilize a compact coronagraph to monitor the Sun’s activity and inform solar wind measurements. The observatory is the first satellite to be dedicated to continuous, operational space weather observations. After reaching L1, the spacecraft will be renamed to Space Weather Observations at L1 to Advance Readiness 1 (SOLAR-1), with the SOLAR-2 observatory to arrive at L1 in the coming years.
Artist’s impression of SWFO-L1. (Credit: NOAA)
SWFO-L1 features four instruments to facilitate its continuous observations of the Sun. The first is the Solar Wind Plasma Sensor (SWiPS), which features two identical electrostatic analyzers that will measure the velocity, density, and temperature of ions in solar wind. Next is the SupraThermal Ion Sensor (STIS), a solid-state spectrometer that will measure suprathermal ions and electrons across various energy levels.
The magnetometer (MAG) instrument, much like IMAP’s MAG, will use two magnetometers to measure the magnetic field generated by solar wind. The last of the four instruments is the Compact Coronagraph (CCOR), which will measure the density structure of the Sun’s outer atmosphere, the corona.
NOAA will operate SWFO-L1 once it arrives at L1, which is expected to occur several months after launch.
Carruthers Geocorona Observatory
The third and final payload launching on Wednesday’s mission is the Carruthers Geocorona Observatory, which was jointly developed by NASA and the University of Illinois. As its name suggests, the observatory will investigate the geocorona — the luminous portion of Earth’s exosphere, or its outermost atmospheric layer. Little is known about Earth’s geocorona, and Carruthers will be the first mission fully dedicated to studying it.
Artist’s impression of the Carruthers Geocorona Observatory observing Earth. (Credit: NASA)
The geocorona is highly expansive, spanning from approximately 15 to around 100 Earth radii. For context, one Earth radius is approximately 6,357 km, with the Moon orbiting around 60 Earth radii from Earth.
The Carruthers Geocorona Observatory has two primary science goals and objectives: to map the geocorona’s response to space weather events, such as coronal mass ejections, and to identify the sources of the geocorona. When charged particles emitted by the Sun travel to Earth, the first atmospheric layer they encounter is the exosphere, which subsequently disturbs the geocorona. Understanding how the geocorona changes in response to interactions with charged particles will inform scientists about how Earth’s overall atmosphere reacts to space weather events, as well as what may be causing the geocorona to form.
The observatory will feature two ultraviolet cameras: a wide-field imager (WFI) and a narrow-field imager (NFI), providing a range of observation options for scientists using the observatory. Carruthers will also feature COSSMo, a student-developed instrument that will measure the brightness of the Sun in ultraviolet and X-rays. With all components assembled, the observatory masses around 241 kg and is approximately the size of a loveseat sofa.
NASA will operate the Carruthers Geocorona Observatory after its launch on a Falcon 9. The observatory’s primary mission is expected to last two years.
(Lead image: Falcon 9 launching the NASA IMAP mission on Sept. 24, 2025. Credit: Max Evans for NSF)
