After nearly nine years of planning, preparation, and even once being slated for cancellation entirely, NASA’s Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) Earth-observation mission lifted off from Launch Complex 40 at Cape Canaveral Space Force Station on February 8, at 1:33:36 AM. This nearly billion dollar mission represents almost a decade of work, with the goal of revolutionizing our understanding of Earth’s dynamic oceans.
While the liftoff took place on time on Thursday morning, PACE’s journey to the launch pad was not easy. After passing through its Key Decision Points in 2016, a series of key readiness milestones, the political environment around the mission and climate monitoring changed significantly. The Trump administration moved to cancel the mission alongside other climate programs in late 2017, threatening to derail the program and severely limit funding for climate research. The mission was ultimately saved by the 2018 Omnibus Spending bill, which granted 20.7 billion dollars to the agency and enabled the restoration of several “at risk” projects to full operational status, including PACE and the upcoming Mobile Launcher 2 for NASA’s Artemis program.
Originally scheduled for Tuesday, February 6, a strong weather system over the Space Coast forced SpaceX and NASA to stand down from their launch operations, and resulted in two consecutive 24 hour resets. Thursday’s weather improved to 95% go, up from 40% and 50% on the first two days. Weather has been a concern across multiple SpaceX operations this week, with the commercial Axiom-3 mission’s return being delayed multiple times, and a Starlink mission on the West Coast standing down due to the multiple atmospheric rivers the state is experiencing.
The Falcon 9 first stage booster supporting this launch, B1081, made its fourth flight, lifting off from LC-40 and pitching down range. It previously launched the Crew-7 rotation to the ISS as well as CRS-29 and a Starlink flight. The unique vantage point that PACE requires, a 98º sun synchronous orbit, necessitated a peculiar trajectory, with the vehicle pitching south and performing a “dog-leg” maneuver to enter the polar corridor – overflying some parts of Florida and the Caribbean after liftoff. This flight plan was incredibly common during the early days of the space age, with SpaceX’s Falcon 9 having flown it a total of 11 times since the corridor’s reactivation in 2020. Following successful first stage flight, booster 1081 returned to the launch site at LZ-1 in preparation for future missions.
As a key component of NASA’s Earth Observation program, PACE aims to help better characterize our home planet and study the impacts of a changing world. Controlled by the Ocean Ecology Laboratory at NASA’s Goddard Space Flight Center, PACE will enter orbit with two primary science objectives – to further build upon more than 20 years of NASA’s extensive record of previous climate studies (ocean color, aerosol and cloud data), and to explore new questions about our planet and its ecosystems with state-of-the-art instruments. In doing so, NASA hopes to supplement the many aging instruments that currently function as integral components of the Earth Observation network, and assist future missions in understanding our dynamic planet.
The primary instrument aboard PACE is the Ocean Color Instrument (OCI), a spectrometer that will measure the color of Earth’s oceans across the electromagnetic spectrum in ultraviolet, visible light, and several shortwave infrared bands. The most advanced instrument of its kind, the OCI will provide NASA with never-before-seen insights into the interactions between sunlight and the substances that make up our oceans, like chlorophyll from sea-dwelling phytoplankton. OCI’s co-passengers aboard PACE will include two polarimeters (HARP2, designed by University of Maryland, Baltimore County, and SPEXone, being contributed to the mission from SRON Netherlands Institute for SpaceResearch and Airbus Defence and SpaceNetherlands) that will study how sunlight’s polarization is changed as it passes through Earth’s atmosphere and the aerosols and clouds within it. In addition to using state-of-the-art technology to beam data back to Earth via downlink, PACE will also have an onboard memory capable of collecting nearly 1.7 terabytes of data – one of the highest of any NASA missions to date.
With PACE’s successful liftoff, NASA can begin to turn their eyes towards the next major climate and weather satellite to be launched this year – GOES-U. Set to lift off from Kennedy Space Center on April 30th, the Lockheed Martin built satellite will act as one of NASA’s geostationary eyes in the sky, providing real time coverage of a vast swathe of the planet. With PACE underway, the data will begin to flow once the mission has completed checkout, and our understanding of human impacts to oceans only grows – providing the world with valuable data to tackle the pieces of the climate puzzle.