3, 2, 1...lift off! At 1:33 a.m. ET on Thursday, February 8, a SpaceX Falcon 9 rocket carrying NASA’s PACE (Plankton, Aerosols, Clouds, and Marine Ecosystems) spacecraft launched from Space Launch Complex 40 at the Cape Canaveral Space Station.
The Falcon 9 rocket of the US Space Exploration Technology Company (SpaceX) will be launched from the Cape Canaveral Space Station, carrying the just-launched PACE satellite, which is the abbreviation of Plankton, Aerosol, and Cloud Marine Ecosystem. Once in orbit 676 kilometers (420 miles) above Earth, the newest satellite to join NASA's Earth Observer fleet will observe ocean and land surfaces in more than 100 wavelengths of light, from infrared to the visible spectrum to ultraviolet. It will also examine tiny particles in the air by looking at the reflection and scattering of light, using a method similar to looking through polarized sunglasses.
Combined with measurements from the new satellites, scientists and citizens will have a more detailed understanding of life near the ocean surface, the composition and abundance of aerosols in the atmosphere (such as dust, wildfire smoke, pollution and sea salt), and how both influence and are affected by climate change.
For NASA and the ocean science community, PACE's launch will be the culmination of nine or 46 years of work.
"There's a better than 50 percent chance that I'm going to be in tears at launch," said Jeremy Werdell, a satellite oceanographer at NASA's Goddard Space Flight Center since 1999 and a project scientist for PACE since 2015. "We stand on the shoulders of previous missions and the people who led them. It's been a long and extraordinary journey," he said.
NASA's first attempt to measure ocean color dates back to the Coastal Zone Color Scanner (CZCS) instrument that flew on the Nimbus 7 satellite from 1978-1986. In 1997, the agency launched the Ocean Observation Wide Field Sensor on the OrbView-2 satellite. SeaWiFS continued to collect ocean data until 2010, and it fundamentally changed our understanding of phytoplankton - the tiny, floating, plant-like organisms that are the "grass" of the ocean. This sensor is the precursor to the new Ocean Color Instrument (OCI) at PACE.
Other instruments and teams have also observed the color of the ocean. The Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on NASA's Terra and Aqua satellites, which have been sailing since 2000 and 2002, complement and extend the record begun by SeaWiFS. More recently, the Visible Infrared Imaging Radiometer Suite (VIIRS) instruments on the Suomi-NPP, NOAA-20, and NOAA-21 satellites have provided a broad view of ocean color. Other instruments - such as the Coastal Ocean Hyperspectral Imager (flying on the space station), Hawkeye (on the SeaHawk CubeSat) and the Carbon Assessment Ocean Radiometer (flying on a NASA research aircraft) - have helped researchers test new ways of observing the ocean.
For atmospheric scientists, the path to PACE also goes back decades. In the late 1970s, the Advanced Very High Resolution Radiometer (AVHRR) first provided some data on aerosol optical depth, a measure of the amount of dust and particles floating in our skies. Later, scientists began measuring these particles every day around the world using the Multi-Angle Imaging Spectroradiometer and MODIS instruments on the Globe. The OMI instrument on the Aura satellite and the successor OMPS instrument on the Suomi-NPP satellite provide additional unique perspectives on aerosols. The HARP instrument flew on CubeSats from 2019-2022, providing a direct test of the technology now flying on PACE as HARP2.
The origins of PACE began around 2007. NASA and other federal agencies asked the National Research Council to study and propose new tools and measurements for studying Earth from space. Their report (called the Decadal Survey) recommended a mission that ultimately led to the A (eroding sol) and C (ring) components of the PACE mission. The new ocean color sensor was inspired by a climate initiative launched by NASA in 2010.
By 2012, NASA scientists and engineers began sketching out rough ideas for PACE, and in 2014, the broader scientific community began digging into the details. By 2015, NASA Goddard began recruiting personnel for the new mission - including Jeremy Waddell - and by 2016, the agency announced the formal development of the PACE mission.
From that moment in 2016, critical decision point A, to this week's launch, hundreds of people put in thousands of hours of effort... including months of working during a global pandemic and methodically and thoughtfully testing every idea, every design, and every component.