SpaceX Set for Sunday Sea Satellite Launch, Booster Recovery Attempt
SpaceX is set to launch a sea level-monitoring satellite from the California coast this Sunday, while attempting to land the rocket's spent first stage on a floating drone ship in the Pacific Ocean.
The Jason-3 spacecraft is scheduled to lift off from Vandenberg Air Force Base Sunday, January 17 during a 30-second window that opens at 1:42 p.m. EST (18:42 UTC). After providing an initial boost toward orbit, the Falcon 9 rocket's first stage will separate, drop away and use a series of engine burns to fly back to one of SpaceX's autonomous landing platforms, which use thrusters to position themselves under descending rockets.
On Monday evening, SpaceX's Jason-3 Falcon 9 rocket was test-fired at Vandenberg Air Force Base for 7 seconds.
SpaceX has leased an area to build a west coast landing zone, but it wasn't clear what drove the final decision to use the drone ship. The vessels are used when a return to land is not feasible, including when the Falcon's first stage must reach a higher velocity before separation. Assuming a combined upper stage and payload mass of 125 metric tons, Musk said a velocity of 5,000 kilometers per hour was slow enough to return the booster to land, while 8,000 kilometers per hour necessitated use of a drone ship.
The Jason-3 satellite weighs 510 kilograms, while each of the 11 ORBCOMM satellites launched in December weighed 170 kilograms, for a total payload mass of about 1.8 metric tons. But Jason-3 is headed to a 1380 by 2328-kilometer orbit, much higher than the ORCOMM payload's 750 by 615-kilometer trajectory. Additionally, west coast launches—which are used to send spacecraft to high-inclination orbits—lose the speed advantage provided by the direction of the Earth's rotation. The Jason-3 Falcon booster is also not equipped with the high-thrust upgrades introduced during the December ORBCOMM mission.
Jason-3 is co-sponsored by NASA, NOAA, the French space agency CNES, and the European climate satellite collective EUMETSAT. It uses a radar altimeter to measure the height of the sea level within just a few centimeters. The data are used for climate modeling, as well as studying tides, hurricanes and tsunamis.
The satellite is the fourth U.S. co-sponsored sea height mission, dating back to TOPEX/Poseidon in 1992. Two Jason satellites followed that mission, named after the mythological Greek leader of the sea-faring Argonauts. Jason-3 will start by precisely flying one minute behind Jason-2, giving scientists the opportunity to compare sensor readings between the two spacecraft. Jason-2 will eventually be shepherded into a different orbit.