SpaceX successfully launched the SARah 1 radar satellite for Bundeswehr on their Falcon 9 Block 5. Having lifted off from Space Launch Complex 4 East, at the Vandenberg Space Force base, in California, the Falcon 9 placed the SARah 1 satellite and other rideshare satellites into a 750 km Sun-Synchronous Orbit.
The SARah 1 satellite is a radar reconnaissance satellite that is built by Airbus Defense and Space and operated by the German armed forces, called Bundeswehr. The satellite is set to replace the aging SAR-Lupe constellation, which, as the name implies, is a Synthetic Aperture Radar (SAR) constellation that the German government currently uses for reconnaissance.
The SAR-Lupe constellation will be replaced by the SARah1, SARah 2, and SARah 3 satellites; the first satellite, SARah 1, will be equipped with a phased array antenna which will increase the resolution of the SAR constellation, past that of SAR-Lupe. SARah 2 and SARah 3 will be two “reflector antenna” satellites, meaning they will fly in formation with SARah 1 to increase the resolution of the constellation.
SARah 1 is equipped with two large solar cells and batteries to provide power to the spacecraft. It is unknown what kind of propulsion the satellite uses.
SARah 1 is joined by several other ride share satellites; however, none of these have been announced.
The Falcon 9 Block 5 is SpaceX’s partially reusable two-stage medium-lift launch vehicle. The vehicle consists of a reusable first stage, an expendable second stage, and, when in payload configuration, a pair of reusable fairing halves.
The Falcon 9 first stage contains 9 Merlin 1D+ sea level engines. Each engine uses an open gas generator cycle and runs on RP-1 and liquid oxygen (LOx). Each engine produces 845 kN of thrust at sea level, with a specific impulse (ISP) of 285 seconds, and 934 kN in a vacuum with an ISP of 313 seconds. Due to the powerful nature of the engine, and the large amount of them, the Falcon 9 first stage is able to lose an engine right off the pad, or up to two later in flight, and be able to successfully place the payload into orbit.
The Merlin engines are ignited by triethylaluminum and triethylborane (TEA-TEB), which instantaneously burst into flames when mixed in the presence of oxygen. During static fire and launch the TEA-TEB is provided by the ground service equipment. However, as the Falcon 9 first stage is able to propulsively land, three of the Merlin engines (E1, E5, and E9) contain TEA-TEB canisters to relight for the boost back, reentry, and landing burns.
The Falcon 9 second stage is the only expendable part of the Falcon 9. It contains a singular MVacD engine that produces 992 kN of thrust and an ISP of 348 seconds. The second stage is capable of doing several burns, allowing the Falcon 9 to put payloads in several different orbits.
For missions with many burns and/or long coasts between burns, the second stage is able to be equipped with a mission extension package. When the second stage has this package it has a grey strip, which helps keep the RP-1 warm, an increased number of composite-overwrapped pressure vessels (COPVs) for pressurization control, and additional TEA-TEB.
The booster that supported the SARah 1 mission is B1071. This booster had supported two previous flights, making its designation for this mission B1071-3; this changed to B1071-4 upon successful landing
Following stage separation, the Falcon 9 conducted three burns. These burns softly touched down the booster on SpaceX’s landing zone LZ-4.
The Falcon 9’s fairing consists of two dissimilar reusable halves. The first half (the half that faces away from the transport erector) is called the active half, and houses the pneumatics for the separation system. The other fairing half is called the passive half. As the name implies, this half plays a purely passive role in the fairing separation process, as it relies on the pneumatics from the active half.
Both fairing halves are equipped with cold gas thrusters and a parafoil which are used to softly touch down the fairing half in the ocean. SpaceX used to attempt to catch the fairing halves, however, at the end of 2020 this program was canceled due to safety risks and a low success rate. On SARah 1, SpaceX attempted to recover the fairing halves from the water with their recovery vessel NRC Quest.
In 2021, SpaceX started flying a new version of the Falcon 9 fairing. The new “upgraded” version has vents only at the top of each fairing half, by the gap between the halves, whereas the old version had vents placed spread equidistantly around the base of the fairing. Moving the vents decreases the chance of water getting into the fairing, making the chance of a successful scoop significantly higher.
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