SpaceX Falcon 9 Block 5 - NROL-85 - Launched April 17, 2022
Screenshot from SpaceX Webcast of the launch of NROL-85
Mission Rundown: SpaceX Falcon 9 B5 - NROL-85
Written: August 9, 2022
Darkness. Camera. Bedroom. To sleepy
On Sunday, April 17 for SpaceX Falcon 9’s launch of the NROL-85 mission from Space Launch Complex 4 East (SLC-4E) at Vandenberg Space Force Base in California. The instantaneous launch window is at 06:13 a.m. PDT.
The Falcon 9 first stage booster supporting this mission previously launched the NROL-87 mission in February 2022. Following stage separation, Falcon 9’s first stage will return and land again on Landing Zone 4 at Vandenberg Space Force Base in California.
This was the second launch of the B1071-2 booster, which successfully touched down on Landing Zone 4 - LZ-4 some 8 minutes after launch.
B1071-2 performed a static fire test 19:00 PDT April 5 after refurbishment and waiting for a west coast launch out of SLC-4. SpaceX has omitted this safety precaution many times so far. It is not required to perform a static fire test inhouse missions like Starlink, that was to save money and time before the launch.
SpaceX is the first entity ever that recovers and reflies its fairings. After being jettisoned, the two fairing halves will use cold gas thrusters to orientate themselves as they descend through the atmosphere. Once at a lower altitude, they will deploy drogue chutes and parafoils to help them glide down to a soft landing for recovery.
Falcon fairings halfs have been recovered and reused since 2019. Improved design changes and overall refurbishment procedures have decreased the effects of water landings and led to an increased recovery rate of fairings.
The fairings are a new pair Type 3.2. Both fairings survived the landing. The active fairing supported 3 missions. The passive fairing half were also on 3 missions. Active fairings are equipped with four pushrods to separate the two fairings halfs.
Fairings used to have evenly spaced venting ports that have been redesigned a number of times by having first ten, then eight and now having their venting ports built as close pairs along the fairing edge. This prevents saltwater from the ocean from flooding and sinking the fairing, and makes refurbishment toward the next flight easier.
There are two models: Type 3.1 fairing with 4x2 venting ports, thermal steel tip, lowered protrusion and no acoustic tiles and the Type 3.2 with payload protecting acoustic tiles.
After lift off from Space Launch Complex 4E, SLC-4E, Falcon 9 took a southward trajectory as it climbed through the atmosphere. The first stage’s nine Merlin-1D# engines cut off around the T+2 minutes 30 seconds mark, with stage separation and a 1st stage 150° flip maneuver following within seconds after MECO.
The second stage continued NROL-85’s journey to orbit while the first stage performed a 48 second long boost back burn to put it on a course back to the launch site.
Unlike most recent Falcon 9 launches from Florida, the NROL-85 flight’s booster did not need a drone ship sent out to the Pacific to recover it. Instead it flew a return to launch site (RTLS) profile, with the booster touching down on the concrete pad at Landing Zone 4 (LZ-4) back at the Cape.
After the boostback burn was completed, B1071-1 positioned itself for atmospheric entry before conducting an entry burn to protect the stage from excess heating — fighting fire with fire — by slowing the stage down. The final landing burn began shortly before touchdown, slowing the booster to a soft landing at LZ-4.
SLC-4 is Falcon 9’s launch and landing site at VSFB. The entire complex is composed of two launch sites: SLC-4E (East) and SLC-4W (West). SLC-4E is used as Falcon 9’s launch site. It was first used for Falcon 9 in September 2013 on the CSA’s CASSIOPE mission. Since then, it has been used 20 more times, with NROL-85 the 22nd SpaceX launch from the pad at Vandenberg Space Force Base in California.
SLC-4W was unused for Falcon 9 launches. It was instead converted from a Titan launch site to a landing pad in the mid to late 2010s. Now named LZ-4, it was first used in a first-stage, West Coast Return to Launch Site (RTLS) landing in October 2018 on the SAOCOM-1A mission. Since then, it has been used five times.
The Secret Payload
The National Reconnaissance Office is a government agency that is a part of the US Department of Defense. Since its formation in 1961, the NRO has been responsible for the US’s reconnaissance satellites. Every year, the NRO launches new payloads into space, with more missions set to launch this year following NROL-85.
This is SpaceX's fourth overall mission for the NRO. In 2017, 2020 and 2022, SpaceX launched the NROL-76, NROL-108 and NROL-87 missions, respectively. They were likely technology demonstration missions and were placed in LEO and SSO.
It is thought that the pair of satellites are part of the NRO’s Intruder mission, which is part of the US Navy’s Naval Ocean Surveillance System (NOSS). NOSS was created during the 1970s with the goal of creating an accurate geolocation map of all of the USSR’s ground and sea assets. The satellites are signal intelligence (SIGNIT) satellites.
Based on the pattern of previous launches, Intruder satellites are typically replaced after about ten years in orbit, although some older spacecraft may be kept in service after their replacements reach orbit. There are currently two pairs of NOSS spacecraft that appear to be due for replacement: USA-229 was launched as NROL-34 in April 2011, while USA-238 was launched as NROL-36 in September 2012. NROL-85 appears to be targeting the same orbital plane as USA-238.
NROL-85 rode to orbit just over eleven years after NROL-34, the mission that deployed USA-229. That launch was somewhat unusual in that it was the only Intruder pair to use an Atlas V 411 rocket instead of the 401 configuration. This was believed to be to allow the satellites to be inserted into orbit with a single burn of the rocket’s upper stage – after a mishap during the coast between two burns on the previous launch had left the NRO’s satellites in a slightly off-target – but recoverable – orbit.
Because USA-327 is part of a newer pair of Intruder satellites than USA-229 and USA-328, it is not immediately clear why the newer spacecraft appear to be in line to be replaced first. This could be down to the operational status of the satellites, changes in the structure of the constellation, or other requirements determined by the NRO.
Intruder A & B must still be together with one of them acting as a spare awaiting the final failure of the last gasp of the old satellites.
Intruder B: Can’t wait to inherit the Sky.
As for NROL-85, not much is known about the payload. The contract called for Falcon 9 to deliver two payloads first to a 1220 km circular low earth orbit (LEO) with a 63.5-degree inclination then the second payload to another unknown orbit.
The landing at LZ-4 makes the payload be about 10 000 kg and school bus sized.
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