SpaceX Falcon 9 Block 5 - CRS-23 SpX-23 - Launching August 29, 2021
Screenshot from NASA/SpaceX shared Webcast of the CRS-23
Mission Rundown: SpaceX Falcon 9 Block 5 - CRS-23
Written: August 30, 2021
Summer’s over, School’s in and Dragon’s up
Sunday’s CRS-23 launch from LC-39A occurred on August 29 at 03:14:48 EDT - 07:14:48 UTC. Dragon then completed the docking with the ISS on Monday.
Dragon CRS-2 SpX-23 is a Commercial Resupply Service mission that will be heading to the International Space Station (ISS). SpaceX was awarded this mission by NASA in 2016 and will launch it on its Falcon 9 Block 5 rocket using a Cargo Dragon 2, C208-2. The rocket will lift off from Launch Complex 39A, at the Kennedy Space Center in Florida. This mission will mark the third flight for SpaceX under NASA’s CRS Phase 2 contract.
The ISS is a lab like no other, so are dozens of new experiments that will be delivered there by SpaceX’s Dragon. Moreover, this mission will bring the GITAI S1 Robotic Arm Tech Demo to the ISS and deploy ELaNa 37’s 3 CubeSats.
B1061 will after this fourth launch with CRS-23 changes its designation to B1061-4.
B1061-4 did perform a static fire test after refurbishment and waiting for an east coast launch out of the Cape. SpaceX has since Starlink V1.0 L08 omitted this safety precaution many times so far. It is not required to perform a static fire test in house missions like Starlink. Only one mission other than Starlink has omitted the static fire test.
Cargo Dragon Payload
Dragon C208-2 will separate from the second stage of the Falcon 9 Block 5 at ~12 min after launch. After that, it will perform a series of thruster firings to adjust its orbit and reach the ISS. The current schedule suggests that the spacecraft will arrive at the ISS one day later, on August 30, at 11:00 EDT (15:00 UTC). Dragon will autonomously dock to the ISS’ Harmony module. Upon Dragon’s arrival, the crew will proceed with unloading the 2200 kg cargo.
Dragon C208-2 will spend around two months at the ISS. Its mission will end on October 28, 2021. After that, the spacecraft will travel back to Earth and will splash down under parachutes in the Atlantic ocean, returning research and cargo to Earth.
Starting with CRS-2 SpX-23, SpaceX’ cargo missions will have an extended duration – from two months and beyond.
Dragon C208-2 will double as an extra space science laboratory where 4 experiments will share power, downlink data streams and data storage from Dragon C208-2 internal supply. One experiment will be moved from its current home on ISS to its new location on Dragon C208-2, where it will join 3 already installed experiments.
The redesign of Cargo Dragon Capsules will extend ISS ability to conduct experiments, and it seems ISS is due for an extension with an extra laboratory module some time soon.
The Cargo Dragon 2
CRS-23 marks the third launch of SpaceX’s upgraded Dragon 2 spacecraft.
Dragon capsule C208 during processing at SpaceX HQ in Hawthorne prior to CRS-21
Cargo Dragon 2 is essentially a Crew Dragon, without an abort system, so it has all of the upgrades from Crew Dragon. Most importantly, Dragon 2 is designed to be reused up to 5 times, with a turnaround time of under 6 months, which is significantly lower than Dragon One; Dragon One’s fastest turnaround time was 418 days, with most turnaround times being significantly longer.
Dragon 1 was unable to dock with the International Space Station. Meaning that Dragon 1 would hold a position away from the ISS. In this position the Canadarm would capture the spacecraft, and attaching it to the ISS. This is called berthing.
Dragon 2 autonomously attaches itself and docks to the ISS. CRS-23 will mark the seventh fully autonomous docking SpaceX has completed. Since its inaugural flight, Dragon 2 has flown 9 times — 3 crewed and 6 uncrewed.
Cargo Dragon 2’s trunk is also different from both Dragon 1’s and Crew Dragon’s. Dragon 2 has its solar panels integrated into its trunk, while Dragon 1 had a deployable solar array from its trunk. Crew Dragon is equipped with 4 fins, which are used for aerodynamic control during ascent. Cargo Dragon 2’s trunk only has 2 solar cell fins.
Externally, Cargo Dragon 2 differs from its crewed counterpart, lacking windows and the SuperDragon abort system. The differences between Crew Dragon and Cargo Dragon are derived from the fact that Cargo Dragon is not required to have launch escape capability. Crew Dragon is fitted with eight SpaceX-developed SuperDraco engines, located in four, two engine clusters around the outside of the capsule, which are there to pull the capsule and its crew to safety away from a Falcon 9 in the event of a catastrophic failure during fueling or launch.
Since Cargo Dragon does not carry crew, the spacecraft does not have to carry those systems; therefore the SuperDracos have been removed from the Cargo Dragon capsule giving a mass reduction that allows for additional cargo to be carried to ISS.
Cargo Dragon 2 also lacks all of the life support and onboard control systems present on Crew Dragon that are needed for humans. Instead, it carries minimal support systems to ensure conditions are kept acceptable for hatch opening on the Station and ISS Crew ingress to the vehicle.
Cargo Dragon 2 is also significantly more massive, with a dry mass of ~12,000 kg. With this mass increase Dragon 2 is able to carry ~50% more science to the ISS than Dragon One. Because of this, missions past CRS-21 will stay docked to the ISS for 3 months, rather than the 1 month that CRS-21 stayed docked.
Dragon 2’s nose cone is also significantly different as it opens instead of being jettisoned on ascent. It is protecting the docking mechanism.
At a press conference after Crew-1, Gwynne Shotwell said SpaceX is expecting to have a fleet of 8 dragons: 5 Crew Dragons and 3 Cargo Dragons. This will allow SpaceX to conduct up to 25 crewed missions and 15 resupply missions.
Unlike prior cargo resupply missions, the new Cargo Dragon 2 carried too much mass to permit a Return To Launch Site (RTLS) landing of the Falcon 9 first stage. Instead, the first stage — like Crew Dragon, from which Cargo Dragon is now derived — made use of a newly built drone ship “A Shortfall Of Gravitas'' in the Atlantic for landing and recovery.
A Shortfall Of Gravitas
‘A Shortfall of Gravitas’ (ASOG) began life as a barge named Marmac 302, making her a relative of SpaceX’s other two drone ships. Just Read the Instructions (JRTI) and Of Course I Still Love You (OCISLY) are designated Marmac 303 and 304, respectively. SpaceX’s original droneship, also named Just Read the Instructions, was Marmac 300 and supported three missions in 2015, never completing a successful recovery.
On July 9, ASOG left Louisiana for Port Canaveral, Florida. After completing a sea trial offshore, the ship and its tug—Finn Falgout—turned on course towards Florida.
Overall, ASOG appears to be more modern than the others, and her deck lacks the thrown together look of OCISLY and JRTI. The sea van containers used to hold navigational, electrical, and other equipment have largely been contained within a purpose-built superstructure.
The “wings,” or structural pieces added to the sides of the deck in order to increase landing area, also appear to be different, with the corners removed from the normal rectangular shape. While this extra landing area may have been useful in early experimental landings, SpaceX’s matured recovery systems have produced very precise landings more recently.
ASOG features four large thrusters on each corner of the ship which appear to be the same type of thrusters installed on JRTI. The diesel electric engines used to power the thrusters are located within the black superstructure.
While the other drone ships require a tug boat to provide propulsion for the entire several day journey to and from a landing zone, usually several hundred kilometers offshore, Musk confirmed on Twitter that ASOG can indeed operate without a tug. Regulations may still require tugs to move ASOG in and out of port before an autonomous system takes over just offshore, and ASOG’s thrusters will still perform station keeping once at the landing zone, just like the propulsion systems on OCISLY and JRTI.
Like its sisters, ASOG will feature an Octagrabber robot used to secure boosters to its deck after landing. The Octagrabber was built at SpaceX’s Cidco Road facility in Florida, just like the one given to Just Read the Instructions after its move to the east coast.
Prior to ASOG’s arrival, SpaceX operated both JRTI and OCISLY on the east coast. With a drone ship coming, however, and the resumption of Falcon 9 launches from Vandenberg, California, on the horizon, the company opted to send the oldest of the three drone ships OCISLY to the Port of Long Beach via the Panama Canal.
OCISLY completed the journey in around 1 month; she rode on top of the massive transport ship Mighty Servant 1—a ship that can submerge itself in order to take on large cargo. This allowed the droneship to complete the journey more quickly than if it had been towed by a tug the entire way.
While SpaceX launch activity has decreased for the short term future, the company is now in a position to resume launching with an even greater cadence—the vast majority of these launches supporting the company’s Starlink satellite internet constellation. SpaceX plans to launch batches of Starlink satellites to polar orbits from both the east and west coast, as well as continuing mid-inclination launches from Florida.
These next Starlink V1.5 will be upgraded and may feature laser inter-satellite links, an important evolution for the Starlink network. The Starlink launch salvo will likely resume in September.
