SpaceX Launches NASA's Earth-observation Satellite, PACE To Polar Orbit

The nearly $1 billion PACE(Plankton, Aerosol, Cloud, ocean Ecosystem) mission launched atop a SpaceX Falcon 9 rocket from Cape Canaveral's Space Launch Complex 40(SLC-40) today (Feb. 8) at 0633 UTC.

The Falcon 9's first stage came back for a vertical touchdown at SpaceX's Landing Zone 1 about 7.5 minutes after launch. It was the fourth launch and landing for this particular booster, according to the company's mission description.

Five minutes later, the rocket's upper stage deployed PACE into a sun-synchronous orbit (SSO) about 677 kilometers(km) above Earth -- roughly 70% higher than the orbit the International Space Station flies. SSOs are popular destinations for spy and weather satellites because in those orbits which go over Earth's poles, spacecraft see each patch of ground at the same solar time every day. Lighting conditions are therefore consistent, allowing it to monitor or detect changes on Earth's surface more easily.

PACE mission team will be working to get the 3.2 meters long spacecraft and its various subsystems up to speed. When up and running, the satellite will make key observations of Earth's atmosphere and climate and allow scientists to better assess the health of our oceans.

"PACE's unprecedented spectral coverage will provide the first-ever global measurements designed to identify phytoplankton community composition," NASA officials wrote in a PACE mission description. "This will significantly improve our ability to understand Earth's changing marine ecosystems, manage natural resources such as fisheries and identify harmful algal blooms."

During a Sunday briefing NASA's chief scientist and senior climate advisor, Kate Calvin said: "PACE is going to provide more information on oceans and atmosphere, including providing new ways to study how the ocean and atmosphere exchange carbon." She added, "In addition to the information PACE will provide that helps us understand long-term climate, PACE will also give us information about oceans and air quality that can help people today."

PACE's work will be done by three instruments. One of them, a spectrometer called the Ocean Color Instrument (OCI), will map out the ocean's many hues in great detail and an unprecedented range, from near-infrared wavelengths all way to the ultraviolet.

These colors are determined by the interaction of sunlight with particles in seawater, such as the chlorophyll produced by photosynthetic plankton, the base of the marine food web. So according to PACE team members, OCI will reveal quite a bit about the health and status of ocean ecosystems.

The satellite's other two instruments are polarimeters. They'll measure how the oscillation of light in a plane, known as its polarization, is affected by passage through the ocean, clouds and aerosols (particles suspended in the atmosphere).

"Measuring polarization states of UV-to-shortwave light at various angles provides detailed information on the atmosphere and ocean, such as particle size and composition," NASA officials wrote in the mission description.

PACE is the first U.S. government mission to launch to a polar orbit from Florida since Nov. 30, 1960. On that day, a Thor Able Star rocket took off on such a trajectory but failed, raining debris down on Cuba, some of which apparently killed a cow. Rather than risk further incidents, the U.S. decided to conduct all of its subsequent polar launches from Vandenberg Air Force Base (now Vandenberg Space Force Base) in California — until now.

However, PACE wasn't the first mission of any type to launch to polar orbit from Florida's Space Coast in six decades: SpaceX had completed 11 such commercial missions before this PACE mission.

WATCH SpaceX launch of PACE mission