NASA's newest Earth observation satellite has made it off the chopping block all the way into orbit.
The nearly $1 billion PACE mission, which the Trump administration tried to cancel four times, launched early this morning (Feb. 8) atop a SpaceX Falcon 9 rocket from the Cape Canaveral Space Force Station in Florida.
When operational, PACE will make important observations of Earth's atmosphere and climate and allow scientists to assess the health of our oceans like never before.
"What I'm most excited about is that PACE will so profoundly advance our understanding of how our oceans work and how they relate to the broader Earth system," said Karen St. Germain, director of NASA's Earth Science Division, during a prelaunch briefing on Sunday (February 4).
"PACE is going to show us the biology of the oceans on a scale we have never been able to see before," she added.
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A smooth, fast launch
The Falcon 9 lifted off from Cape Canaveral's Space Launch Complex 40 today at 1:33 a.m. EST (06:33 GMT), after several days of delays caused by bad weather.
About 7.5 minutes after launch, the rocket's first stage returned for a vertical landing at Landing Zone 1, a SpaceX facility on the Cape. According to a SpaceX mission description, it was the fourth launch and landing for this particular booster.
Just five minutes later, the Falcon 9 upper stage put PACE (whose name is an abbreviation for Plankton, Aerosol, Cloud, ocean Ecosystem) into a sun-synchronous orbit (SSO) about 677 kilometers above Earth - about 70% higher . than the International Space Station flies.
In SSOs, which pass over the Earth's poles, satellites see every patch of ground at the same solar time every day. Light conditions are therefore consistent, making it easier for spacecraft to track or detect changes on the Earth's surface. For this reason, SSOs are popular destinations for weather and spy satellites.
In fact, PACE is the first U.S. government mission to launch into polar orbit from Florida since November 30, 1960. On that day, a Thor Able Star rocket took off on such a trajectory but failed, raining debris on Cuba. , some of which apparently killed a cow. Rather than risk further incidents, the US decided to conduct all subsequent polar launches from Vandenberg Air Force Base (now Vandenberg Space Force Base) in California - until now.
That said, PACE wasn't the first mission of any type to launch into polar orbit from Florida's Space Coast in six decades: SpaceX had completed 11 such commercial missions before PACE hit the road.
The color of the ocean
PACE's companions will now work to get the 10.5-foot-long (3.2 meters) spacecraft and its various subsystems up to speed. After this check-out period, the satellite can begin its scientific work.
That work will be done by three instruments. One of these, a spectrometer called the Ocean Color Instrument (OCI), will map the ocean's many hues in incredible detail and an unprecedented range, from near-infrared wavelengths 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 OCI will reveal a lot about the health and status of ocean ecosystems, PACE team members said.
"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."
The satellite's other two instruments are polarimeters. They will measure how the oscillation of light in a plane, known as its polarization, is affected by its passage through the ocean, clouds and aerosols (particles floating in the atmosphere).
"Measuring the polarization states of UV-to-shortwave light at different angles provides detailed information about the atmosphere and ocean, such as particle size and composition," NASA officials wrote in the mission description.
So PACE's contributions to earth and climate science will be many and varied, agency officials emphasize.
"PACE will provide more information about oceans and the atmosphere, including new ways to study how the ocean and atmosphere exchange carbon," Kate Calvin, NASA's chief scientist and senior climate advisor, said during Sunday's briefing.
"In addition to the information PACE will provide that helps us understand the long-term climate, PACE will also give us information about oceans and air quality that can help people today," she added.
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A difficult road to the launch pad
PACE has endured its fair share of setbacks on its way to the launch pad. For example, President Donald Trump's administration tried to cancel the mission four times, in its budget proposals for fiscal years 2018, 2019, 2020 and 2021. But Congress allocated the necessary funds each time, saving PACE from the chopping block. .
The mission has also faced delays and cost overruns. In 2014, NASA capped the mission's total price tag at $805 million, with a launch scheduled for 2022. However, the cost has risen to $948 million.
But the wait and the money will all be worth it, said St. Germain, who compared PACE favorably to NASA's flagship James Webb Space Telescope.
"It's going to teach us about the oceans the same way Webb teaches us about the cosmos," she said.
