SpaceX Falcon 9 Block 5 - CRS-18 - Launching July 25, 2019
Screenshot of CRS-18 on Space Launch Complex 40 from SpaceX YouTube video
Mission Rundown: SpaceX Falcon 9 B5 - CRS-18
Written: January 7, 2021
Finally a run of the mill flight
At 6:01 p.m. EDT, or 22:01 UTC, on Thursday, July 25, SpaceX launched its eighteenth Commercial Resupply Services mission (CRS-18) from Space Launch Complex 40 (SLC-40) at Cape Canaveral Air Force Station, Florida. Dragon separated from Falcon 9’s second stage about nine minutes after liftoff.
The Dragon spacecraft supporting the CRS-18 mission previously supported the CRS-6 mission in April 2015 and the CRS-13 mission in December 2017. Following stage separation, SpaceX recovered Falcon 9s’ first stage on Landing Zone 1 - LZ-1 at Cape Canaveral Air Force Station, Florida.
Booster B1056-2 previously flew with CRS-17 on May 4, 2019.
A notable difference on the Falcon 9 is a painted gray thermal stripe on the bottom third of the second stage. It’s an experimental passive heat exchanger leading “heat” to/from the LOX tank to the RP-1 tank in outer space.
For CRS missions, maintaining fuel (RP-1 kerosene) and oxidizer (densified Liquid Oxygen) temperatures in the second stage is not as challenging as it is for long coast missions which sometimes require the propellants to be thermally maintained or reconditioned up to six hours after launch – as is the case for some Geostationary Transfer Orbit missions and Defense missions for the U.S. government.
The most challenging aspect of thermal control up until now had been maintaining the densified liquid oxygen’s (LOX’s) temperature and chilling that LOX back down to an acceptable temperature before second stage reignition on long coast flights.
A series of experiments on the second stage after deployments of Dragons on CRS missions have led to the use of this gray stripe. Apparently white paint reflects too much sunlight and the thermal conductivity is nonexistent in the shade.
“Is there a rocket scientist in the room? Somebody here just had a brain freeze.”
The Dragon Payload
NASA has contracted for the CRS-18 mission from SpaceX and therefore determines the primary payload, date/time of launch, and orbital parameters for the Dragon space capsule. It carried the third International Docking Adapter (IDA-3) in its unpressured trunk and it’s weighing 534 kg (1 117 lb). IDA-3 will be attached to the Zenit docking port.
The pressurized capsule carried 1 756 kg of various science and supply materials.
The Dragon spacecraft also featured a handful of ceramic heat shield tiles, meant to flight-test a critical component of the SpaceX Starship spacecraft.
CRS-18 is the 18th commercial resupply mission, which was awarded to SpaceX in February of 2016. This is the third to last Commercial Resupply Mission with Dragon 1, the 5th reuse of Dragon, and the first time a Dragon is reused for a third time.
The Cargo Dragon is expected to arrive at the station ISS within two days after lift off. Once it navigates into position, it will be captured by the Canadarm, and then berthed to the station a few hours later. After about 30 days Dragon will depart ISS, ditch it’s trunk, reenter the atmosphere and splash down in the Pacific Ocean.
SpaceX technicians opened the side hatch of the Dragon vehicle and retrieved the time-critical refrigerated items. The critical cargo items were placed on a fast-boat for the 450 kilometers (280 mi) trip back to California for eventual return to NASA that then took care of the precious science cargo and handled the post-flight analysis of the samples.
The rest of the cargo was unloaded once the Dragon capsule reached SpaceX's test facility in McGregor, Texas.
