Mission Overview

The Surface Water and Ocean Topography (SWOT) mission will survey Earth’s salt- and freshwater bodies, measuring the height of the water in lakes, rivers, reservoirs, and the ocean. The satellite will cover the planet’s surface at least once every 21 days and has a prime mission of three years.

The information on the ocean that SWOT gathers will help researchers better understand how seawater absorbs atmospheric heat and carbon, a process that affects global temperatures and climate change. The satellite’s ability to resolve ocean features less than 13 miles (20 kilometers) across – smaller than previous sea level satellites have observed – will also enable it to collect data close to the coast. These measurements will help give researchers a clearer picture of coastal sea level and, ultimately, how sea surface height will interact with a changing climate to affect things like storm surges and coastal flooding.

SWOT will also provide the first comprehensive global survey of freshwater lakes, rivers, and reservoirs from space. The satellite will measure their surface area, or extent, as well as their height. By helping track changes in water volume over time, the data will better equip scientists and water resource managers to monitor how much water flows into and out of the planet’s freshwater bodies.

The SWOT satellite will launch aboard a SpaceX Falcon 9 rocket, procured by NASA’s Launch Services Program. It will lift off from Space Launch Complex 4E (SLC-4E) at Vandenberg Space Force Base (VSFB) in Central California.

The SWOT spacecraft will be launched no earlier than 6:46 a.m. EST (3:46 a.m. PST) on Dec. 15, 2022. The launch date is based on the readiness of the satellite, the Falcon 9 launch vehicle, and the Western Test Range at VSFB. The launch window is instantaneous and will be the same for subsequent days.

These targeted milestones are accurate as of November 2022 but may change if the launch date changes.

• 2 minutes and 15 seconds after launch: Main engine cutoff (MECO), stage separation, and then second-engine start 1 (SES1) will occur in quick succession. The reusable Falcon 9 first stage will then begin its automated return to the launch site for a powered landing.
• 2 minutes and 59 seconds: After protecting the satellite as the rocket traveled through the atmosphere, the launch vehicle’s nose cone will separate and be jettisoned.
• 8 minutes and 24 seconds: Stage-II engine cutoff (SECO1) will take place, putting the launch vehicle and spacecraft in a parking orbit.
• 42 minutes and 52 seconds: Stage-II first restart (SES2) will occur with a ~5-second burn, followed by stage-II engine cutoff (SECO2).
• 51 minutes and 59 seconds: The launch vehicle and spacecraft will separate.
• 54 minutes and 34 seconds: The spacecraft may make its first (very short) potential partial contact (no engineering data on spacecraft health) with ground stations in South Africa.
• 1 hour and 18 minutes: The spacecraft expected to make its first full ground contact, providing first data on spacecraft health, with ground stations in Sweden and Canada.

The spacecraft will be launched into a non-Sun synchronous orbit with an inclination of 78 degrees. SWOT will orbit at an altitude of 553 miles (891 kilometers) and make 14 orbits per day. The spacecraft will send back about one terabyte of unprocessed data per day and has a prime mission of three years.