SpaceX sends PACE to Space

Early on the morning of the 8th of February, a SpaceX Falcon 9 lifted off from Space Launch Complex 40 in Cape Canaveral, located in Florida. The rocket was carrying NASA's PACE spacecraft to a sun-synchronous orbit where it will perform its study of the Earth's health below.

The booster that supported this mission, and landed back at Landing Zone 1, was B1081 making its fourth flight. SpaceX was able to land the booster back in Cape Canaveral due to PACE only weighing 1,694 kilograms, leaving enough propellant margin for a 'return to launch site' launch profile.

PACE, or Plankton, Aerosol, Cloud, ocean Ecosystem mission, is a NASA mission to advance information for assessing the condition of the ocean and atmosphere. PACE will orbit the Earth in a sun-synchronous orbit and gather data using two instruments. These Instruments are the Ocean Color Instrument and the Multi-angle Polarimeters.

The Ocean Color Instrument is believed to be a spectrometer used to measure the intensity of light over portions of the electromagnetic spectrum: ultraviolet, visible, near-infrared, and several shortwave infrared bands. The Ocean Color Instrument will enable continuous measurement of light at finer wavelength resolution than previous NASA ocean color sensors, providing detailed information on our global ocean. The color of the ocean is determined by the interaction of sunlight with substances or particles present in seawater such as chlorophyll, a green photosynthetic pigment found in phytoplankton and land plants.

The Multi-angle Polarimeters are believed to be comprised of radiometers used to measure how the oscillation of sunlight within a geometric plane, known as its polarization, is changed by passing through clouds, aerosols, and the ocean. Measuring polarization states of ultraviolet-to-shortwave light at various angles provides detailed information on the atmosphere and ocean, such as particle size and composition.

What is Falcon 9?

Falcon 9 is currently the world's only operational partially reusable medium-lift launch vehicle. The rocket is manufactured and operated by American aerospace company SpaceX. Falcon 9 currently launches from Vandenberg Space Force Base, in California, and Cape Canaveral, in Florida.

SpaceX claims that Falcon 9 can send up to 22,800 kilograms into low Earth orbit when expended or 18,400 kilograms when reused. Similarly, it can send up to 8,300 kilograms into geosynchronous transfer orbit when expended or 5,500 kilograms when reused.

For recovery, Falcon 9 has four grid fins and four landing legs on the first-stage. The first stage either lands vertically on a drone ship or on a landing pad back at its launch site, landing back at the launch site causes a reduction it payload capacity.

The first-stage is powered by nine Merlin 1D engines burning rocket-grade kerosene and liquid oxygen to generate 771 tons of thrust for up to two-minutes and forty-two seconds of burn time.

The second-stage is powered by a single Merlin 1D vacuum engine burning rocket-grade kerosene and liquid oxygen to generate 95 tons of thrust for up to six minutes and thirty-seven seconds of burn time.

On the pad, the rocket is 70 meters tall with the first and second stages 3.7 meters in diameter, the fairing is 5.2 meters in diameter and tapers out from the top of the second-stage. Fully fuelled Falcon 9 weighs approximately 549,000 kilograms.