# Space Weather Follow On-Lagrange 1

Space Weather Follow On-Lagrange 1 (SWFO-L1) is a future spacecraft mission planned to monitor signs of solar storms, which may pose harm to Earth's telecommunication network. The spacecraft will be operated by the National Oceanic and Atmospheric Administration (NOAA), with launch scheduled for no earlier than September 2025. It is planned to be placed at the Sun–Earth L$_1$ Lagrange point, a location between the Earth and the Sun. This will allow SWFO-L1 to continuously watch the solar wind and energetic particles heading for Earth. SWFO-L1 is an ESPA Class Spacecraft, sized for launch on an Evolved Expendable Launch Vehicle Secondary Payload Adapter (ESPA) Grande ring in addition to the rocket's primary payload. The spacecraft's Solar Wind Instrument Suite (SWIS) which includes three instruments will monitor solar wind, and the Compact Coronagraph (CCOR) will monitor the Sun's surroundings to image coronal mass ejection (CME). A CME is a large outburst of plasma sent from the Sun towards interplanetary space.
Together with space weather observation capabilities on the Earth-orbiting GOES-U satellite, SWFO-L1 constitutes the space segment of NOAA's Space Weather Follow On (SWFO) program. The aim of the SWFO program is to ensure the robust continuity of space-based measurement of the critical space weather environment. All of the spacecraft located in L$_1$ which are currently monitoring CMEs and the solar wind have operated beyond their design lifetime. SWFO-L1's SWIS instruments will replace ACE's and DSCOVR's monitoring of solar wind, energetic particles and the interplanetary magnetic field while CCOR will replace SOHO's LASCO (Large Angle and Spectrometric Coronagraph) imaging of CMEs.

## Command and control system

On 5 February 2021, NOAA awarded the SWFO-L1 Command and control contract to L3Harris in Melbourne, Florida. The contract has a total value of US$43.8 million, with a five-year performance period. The SWFO-L1 mission is planned to launch as a rideshare with NASA's Interstellar Mapping and Acceleration Probe (IMAP). The contractor is responsible for up to two years of operations support. This will be accomplished by adding the capability to the existing Geostationary Operational Environmental Satellite-R Series Core Ground System.
NOAA manages the contract. In addition to work at L3Harris' facility in Melbourne, the contractor will install equipment at the NOAA Satellite Operations Facility (NSOF) in Suitland, Maryland; NOAA's Wallops Command and Data Acquisition Station (WCDAS) in Wallops, Virginia; and at NOAA's Consolidated Backup Facility (CBU) in Fairmont, West Virginia.
The work will allow SWFO-L1 to provide continuity of solar wind and coronal mass ejection imagery data from the Lagrange-1 point to NOAA's National Weather Service Space Weather Prediction Center in Boulder, Colorado. These data are critical to support monitoring and timely forecasts of space weather events that have the potential to adversely impact elements vital to national security and economic prosperity, including telecommunication and navigation, satellite systems and the power grid. NOAA is responsible for overall implementation and funding of the SWFO program. The program is managed as an integrated NOAA-NASA program, where NASA serves as NOAA's acquisition agent for the space segment and for launch services. NOAA is responsible for the ground segment including the acquisition, development, test and integration of the SWFO Command and control system.

## Instruments

In April 2020, Southwest Research Institute (SwRI) was awarded a contract to supply SWFO-L1's magnetometer instrument.
On 1 July 2020, on behalf of NOAA, NASA awarded the SWFO-L1 Solar Wind Plasma Sensor (SWiPS) contract to Southwest Research Institute (SwRI) in San Antonio, Texas. SwRI was awarded a contract with a total value of US$15.6 million. The period of performance is 76 months. SWFO-L1 will provide NOAA with the continuity of solar wind data and coronal mass ejection imagery, the National Weather Service's highest priority for space weather observations. University of California, Berkeley was awarded US$7.5 million for the development of the Supra-Thermal Ion Sensor (STIS). The SWFO-L1 satellite, which is planned to launch as a rideshare with the NASA Interstellar Mapping and Acceleration Probe (IMAP), will collect upstream solar wind data and coronal imagery to support NOAA's mission to monitor and forecast space weather events. NOAA is responsible for the Space Weather Follow On program. NASA is the program's flight system procurement agent, and NASA's Goddard Space Flight Center in Greenbelt, Maryland, is the lead for this acquisition.

## Launch

Space Weather Follow On-Lagrange 1 is planned to be launched as a secondary payload on the SpaceX Falcon 9 launch vehicle carrying NASA's Interstellar Mapping and Acceleration Probe (IMAP) spacecraft. As of December 2024, the launch is scheduled for no earlier than September 2025.