The SWOT mission brings together two communities focused on a better understanding of the world's oceans and its terrestrial surface waters. U.S. and French oceanographers and hydrologists and international partners have joined forces to develop this satellite mission to make the first global survey of Earth's surface water, observe the fine details of the ocean's surface topography, and measure how water bodies change over time.


SWOT is being jointly developed by NASA and Centre National D'Etudes Spatiales (CNES) with contributions from the Canadian Space Agency (CSA) and United Kingdom Space Agency.

Launch Vehicle

NASA has selected Space Exploration Technologies (SpaceX) of Hawthorne, California, to provide launch services for SWOT. Launch is targeted for April 2021 on a SpaceX Falcon 9 rocket from Space Launch Complex 4E at Vandenberg Air Force Base in California. NASA's Launch Services Program at Kennedy Space Center in Florida will manage the SpaceX launch service.

Mission Development Timeline

SWOT was one of 15 missions listed in the 2007 National Research Council Decadal Survey of Earth science missions that NASA should implement in the subsequent decade (full report available here). In its earliest stages, the mission underwent Concept Studies (Pre-Phase A) and Concept & Technology Development (Phase A).

In early 2015, SWOT entered Phase B, Preliminary Design & Technology Completion. In 2016, SWOT was approved for implementation and thus entered Phase C (Final Design & Fabrication).

To learn more about SWOT's latest progress towards launch, visit the Flight Systems and Ground Systems pages. To learn about the airborne instrument making measurements similar to those that will be made in space by SWOT to prepare for the hydrology post-launch Cal/Val, visit the AirSWOT page.

SWOT will launch in Phase D. Approximately the first six months after launch, it will be in a "fast sampling" mode with a 1-day repeat orbit at an altitude of 857 km (532.5 mi). This initial period will focus on achieving calibration and validation objectives while studying rapidly changing phenomena. The "fast sampling" mode will end with an increase in the observatory's altitude to 891 km (553.6 mi).

Phase E (Operations & Sustainment), nominally lasting three years, will have a 21-day repeat orbit to balance global coverage and frequent sampling. This non-sun-synchronous orbit was chosen to minimize tidal aliasing and ensure coverage of major water bodies on land. SWOT's 120-km-wide (~75-mi-wide) swath will result in overlapping measurements over most of the globe with an average revisit time of 11 days.


SWOT Calibration / Validation Plan (Initial Release)
SWOT Project Mission Performance and Error Budget
[2017] This document presents the top-down error budget for the SWOT mission and its ability to meet the scientific requirements. It includes all of the different systems and subsystems that have a significant contribution to the overall performance of the mission.