Dragon CRS-2 SpX-23 | Falcon 9 Block 5

Lift Off Time
August 29, 2021 07:14 UTC | 03:14 EDT
Mission Name
Dragon CRS-2 SpX-23, a Commercial Resupply Service mission to the International Space Station (ISS)
Launch Provider
(What rocket company launched it?)
(Who paid for this?)
Falcon 9 Block 5 B1061-4
Launch Location
Launch Complex 39A (LC-39A), Kennedy Space Center, Florida, USA
Payload mass
~2,200 kg (4,800 Ib) of cargo
Where did the spacecraft go?
Dragon C208-2 rendezvoused with the ISS, ~400 km low Earth orbit (LEO) at a 51.66° inclination
Did they attempt to recover the first stage?
Where did the first stage land?
It landed on the Autonomous Spaceport Drone Ship A Shortfall Of Gravitas (ASOG)
Did they attempt to recover the fairings?
There are no fairings on the Dragon 2
Were these fairings new?
There are no fairings on the Dragon 2
This was the:
– 1st mission for the ASOG drone ship
2nd flight of Cargo Dragon 2 C208-2
2nd launch of a Robotic Arm to the ISS in 2021
3rd SpaceX launch under the CRS 2 contract
3rd Dragon 2 flight to the ISS in 2021
4th flight of the B1061-4
3rd cargo resupply mission with an upgraded Dragon 2
– 23rd SpaceX Commercial Resupply Services mission
– 21st launch for SpaceX in 2021
– 90th booster landing
– 28th launch of any variant of Dragon
26th visit of any variant of Dragon to the ISS
124th Falcon 9 launch
130th SpaceX mission
84th orbital launch attempt of 2021 (79th successful)
Where to re-watch
SpaceX’s replay

NASA’s replay

How did it go?

Dragon CRS-2 SpX-23 is a Commercial Resupply Service mission that arrived at the International Space Station (ISS) on August 30, 2021. SpaceX was awarded this mission by NASA in 2016 and launched it on its Falcon 9 Block 5 rocket using a Cargo Dragon 2, C208-2.

The rocket lifted off on Sunday, August 30, from Launch Complex 39A, at the Kennedy Space Center in Florida. The first attempt on Saturday was scrubbed in the final minutes due to the no-go range weather. This mission marked the third flight for SpaceX under NASA’s CRS Phase 2 contract.

CRS-2 SpX-23 mission patch
CRS-2 SpX-23 mission patch (Credit: NASA)

CRS-2 SpX-23

The ISS is a lab like no other, so are dozens of new experiments that were delivered there by SpaceX’s Dragon. Moreover, this mission brought GITAI S1 Robotic Arm Tech Demo to the ISS and deployed ELaNa 37 CubeSats.

Research Payloads


REducing Arthritis Dependent Inflammation First Phase (READI FP) is a project that will study how microgravity and space radiation affect normal metabolism of the bone tissue. It is known that astronauts at the ISS show a loss of bone mineral density, which is caused by the process called resorption. This phenomenon is led by the activation of osteoclast cells. This disease can be a serious issue for future long-duration space missions, thus, effective countermeasures need to be found.

The READI FP project will evaluate a protective effect of bio-collagen with a mixture of natural bioactive metabolites (extracted from wine-making wastes) on bone tissue. The results of this study can be crucial not only for astronauts, but also for everyday people here on Earth. For instance, they could contribute to prevention and control of bone loss due to disability, and to osteoporosis in post-menopausal women.

DLR-EAC Retinal Diagnostics Study

The DLR-EAC study aims at implementing small, non-invasive, non-contact retinal imaging devices into daily practice for astronauts. This project will be documenting progression of vision problems that are common among the crew at the ISS (called Space-Associated Neuro-Ocular Syndrome). The tool will use commercially available ophthalmology lens attached to a mobile gadget. Compared to some older eye diagnostics devices, the new ones offer several advantages in size, weight, and diagnostic capability.

DLR-EAC Retinal Diagnostics Study, the hardware, CRS-2 SpX-23
A preflight view of the hardware for DLR-EAC Retinal Diagnostics Study (Credit: DLR/EAC)

The team at the ISS will simply clip the hardware to their onboard iPad Pro. At several time points, crew members will take video images of each other’s retinas, after which the data will be downlinked via the application. Then, a machine learning model will be used to detect retinal abnormalities.

Project Maleth

Maleth is the first ever Maltese mission that went to space! This project was created by the Ministry of Foreign and European Affairs of Malta and Space Applications Services NV/SA (Belgium). It is led by Prof. Joseph Borg, current President of the Malta Association of Biomedical Scientists, whose research interests are experimental haematology and molecular genetics.

A Bio-cube that was sent to the ISS contains human skin microbiome samples from Type 2 Diabetic patients with diabetic foot ulcers that are resistant to treatment. Diabetes is a huge issue not only in Malta (12.2% of the population suffer from this disease) but also worldwide. The study aims at finding a number of biomarkers of this disease, which could give rise to molecular therapy and precision-based medicine. The samples will be analyzed in a multi-omic manner before the launch and at the ISS. This way scientists will be able to determine their adaptation and changes to the space environment.

Project Maleth, CRS-2 SpX-23
A Bio-cube with samples for the project Maleth (Credit: SpaceOMIX)

Another Maltese project will study how microgravity affects haemoglobin expression in humans.

Making Space for Girls Challenge

The 2020 Making Space for Girls challenge was a competition open to young female researches in the United States. Three of the proposed projects won and will fly to the ISS on the CRS-23 mission. All of them will study living organisms in a microgravity. The first one will examine microgravity’s effects on ant behavior, the second one will look at plant growth in space, and the last one will observe brine shrimps (sea monkeys) at the space laboratory.

Student Spaceflights Experiments Program – Mission 15

The Student Spaceflight Experiments Program (SSEP) will launch its 15th mission. Like the previous missions, this one brought several student experiments to the ISS. Four of them will study germination techniques as potential food production options for astronauts on deep space missions. Another will evaluate how tardigrades (water bears) adapt to space. Finally, the sixth experiment will assess aluminum corrosion.


Optical Sensors based on CARbon materials: QUantum BElgium (OSCAR-QUBE) is a team of 15 students from Hasselt University (Belgium) who won the second edition of Orbit Your Thesis! This program is conducted by ESA Academy. As its name suggests, it selects outstanding students’ projects to be launched to the ISS. The first edition started in 2018 with the AIM “Artery In Microgravity” team.

Optical Sensors based on CARbon materials: QUantum BElgium (OSCAR-QUBE), CRS-2 SpX-23
Orbit Your Thesis! hardware OSCAR QUBE (Credit: The European Space Agency)

OSCAR-QUBE is developing a new generation of magnetic field sensors. The core of sensors consists of a single crystal diamond that contains a defect in the crystalline lattice called Nitrogen-Vacancy (NV) centers. This defect can be used as a magnetic field probe and has several unique characteristics such as sub-picotesla sensitivity, fast response (<200 ns) to the changes in the magnetic field, and wide dynamic range (fT – mT). With this approach, the students want to measure the magnetic field in LEO and create a high-resolution map around the Earth.


Among others projects, CRS-2 SpX-23 brought the Advanced Plant EXperiment-08 (APEX-08) to the ISS. This study will try to engineer plants that grow better in microgravity. It was shown that plants grown in space conditions display evidence of stress. All because compounds known as polyamines that usually mitigate stress levels on Earth are not properly expressed under microgravity.

In the APEX-08 project, scientists will work with different genotypes of the Arabidopsis thaliana plant to reveal the one with a more active polyamine metabolic pathway.


Materials International Space Station Experiment-15-NASA (MISSE-15-NASA) arrived to the ISS to evaluate the effect of the low-Earth orbit environment on the characteristics of various materials and components. MISSE-15-NASA will include tests of concrete, protective fiberglass composites, polymer materials, thin-film solar cells, radiation protection materials, and the Electrodynamic Dust Shield (EDS). Moreover, thermal protection coatings that can be used for future spacecraft and reentry heat shields will be among the samples.

The MISSE-15-NASA’s samples (Credit: NASA)


Nanofluidic Implant Communication Experiment (NICE) aims to develop a drug delivery system that can be used on the ISS and operated remotely from Earth. This system is intended to be implanted and release precise doses of a drug on demand over an extended period of time. The device does not use any catheters or moving mechanical components (like an infusion pump), which makes this approach minimally invasive.

The CRS-2 SpX-23 mission delivered these implants immersed in saline so the crew can test remote control between Earth and the ISS. This study will be performed at the station’s Faraday Research Facility using the EXPRESS racks.

GITAI Robotic Arm

Nanoracks-GITAI Robotic Arm is the second robot that was delivered to the ISS this year. The first one was the new European robotic arm (ERA) that was launched together with the Russian science module “Nauka” in July.

Designed by GITAI Japan Inc., the robot will work as a general-purpose helper under the pressurized environment inside the Bishop Airlock. It will operate tools and switches and run scientific experiments. The next step will be to test it outside the ISS in the harsh space environment. The robot will be able to perform tasks both autonomously and via teleoperations. Its arm has eight degrees of freedom and a 1-meter reach.

Nanoracks-GITAI Robotic Arm, CRS-2 SpX-23
Nanoracks-GITAI Robotic Arm (Credit: GITAI)

ELaNa 37 CubeSats

Among the payload in the Dragon spacecraft were three CubeSats that were designed by University of Illinois at Urbana-Champaign, University of Massachusetts Lowell, and Inter-American University of Puerto Rico.

ELaNa is an initiative that was proposed by NASA and is managed by the Launch Services Program (LSP) at NASA’s Kennedy Space Center. The main aim of this program is to collaborate with universities all across the US to design, manufacture, and launch research satellites into space. ELaNa brings university students closer to real space missions, giving them opportunities to dive in and to get involved in the process from A to Z, from designing and assembling CubeSats, to launching and operating them.

CRS-2 SpX-23 Mission Profile

Dragon C208-2 separated from the second stage of the Falcon 9 Block 5 at ~11 min 45 s after launch. After that, it performed a series of thruster firings to adjust its orbit and reach the ISS. The spacecraft arrived at the ISS one day later, on August 30, at 10:30 EDT (14:30 UTC). Dragon autonomously docked to the ISS’ Harmony module. Upon Dragon’s arrival, the crew proceeded with unloading the cargo.

Cargo Dragon 2 after its separation from the upper stage, CRS-23 mission
Cargo Dragon 2 after its separation from the upper stage (Credit: SpaceX via Twitter)

Dragon C208-2 will spend around one months at the ISS. Its mission will end in late September or early October. 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.

Approximate Timeline

All times are approximate.


From Lift-Off
– 00:38:00SpaceX Launch Director verifies go for propellant load
– 00:35:00RP-1 (rocket grade kerosene) loading begins
– 00:35:001st stage LOX (liquid oxygen) loading begins
– 00:16:002nd stage LOX loading begins
– 00:07:00Falcon 9 begins pre-launch engine chill
– 00:05:00Dragon transitions to internal power
– 00:01:00Command flight computer to begin final prelaunch checks
– 00:01:00Propellant tanks pressurize for flight
– 00:00:45SpaceX Launch Director verifies go for launch


From Lift-Off
– 00:00:03Engine controller commands engine ignition sequence to start
+ 00:01:12Maximum dynamic pressure (Max Q)
+ 00:02:27Main engine cutoff (MECO)
+ 00:02:30Stage separation
+ 00:02:38Second engine start-1 (SES-1)
+ 00:02:43First stage boostback burn begins
+ 00:05:49First stage entry burn begins
+ 00:07:38First stage landing
+ 00:08:34Second engine cutoff-1 (SECO-1)
+ 00:11:45Dragon separation

What is Falcon 9 Block 5?

SpaceX’s Falcon 9 Block 5 is a medium-lift launch vehicle that stands out among others for its partial reusability. By re-flying boosters and fairings, SpaceX not only cuts down the cost of space access, but also increases the reliability of the rocket. Block 5 is the final iteration of the Falcon 9 that is designed, manufactured, and operated by SpaceX.

Lift-off of the Falcon 9 Block 5 with Cargo Dragon 2, CRS-21 mission
Lift-off of the Falcon 9 Block 5, CRS-21 mission (Credit: SpaceX)

The rocket consists of a reusable first stage, an interstage, and a second stage. Falcon 9 Block 5 can be flown with either a fairing or a Dragon spacecraft. On the SpX-23 mission, the Cargo Dragon C208-2 was used to deliver research and other payloads to the ISS.

Falcon 9 Block 5 is about 70 meters (229.6 ft) in height and 3.7 meters (12 feet) in diameter. The vehicle’s structures are made of an aluminum-lithium alloy, which results in a total dry mass of 549,054 kg (1,207,920 lb). The rocket’s payload lift capacity to low-Earth orbit (LEO) is 22,800 kg (50,265 lb).

First and Second Stage

First StageSecond Stage
Engine9 Merlin 1D engines1 vacuum optimized Merlin engine
Thrust Per Engine845 kN (190,000 Ibf), sea level
934 kN (209,971 Ibf), vacuum
992 kN (223,100 lbf)
Specific Impulse (ISP)285 s, sea level
313 s, vacuum
348 s

The Falcon 9’s first stage consists of aluminum-lithium alloy tanks for propellants and four landing legs, which are stowed at the base and deploy just before landing. Nine sea-level Merlin 1D engines power this stage. The second stage also consists of tanks for propellants and is powered by a single vacuum optimized Merlin engine or MVac. The main difference between these two variations of the Merlin engine is that the latter has an expanded nozzle that results in improved performance in near-vacuum conditions. The second stage is what carried Dragon to its intended orbit allowing the spacecraft to rendezvous with the ISS.

Merlin engine powers Falcon 9 Block 5 stages
Schematic representation of the Merlin engine. (Credit: Everyday Astronaut)

The Merlin engine runs on rocket-grade kerosene (RP-1) and liquid oxygen (LOx), and uses a gas generator cycle. Falcon 9 uses helium as a pressurant to backfill the propellant tanks as RP-1 and LOx are being consumed by the engines during ascent.

The interstage connects the first and second stages of the vehicle and is responsible for their separation during flight. It also accommodates four hypersonic grid fins at the base. They help to orient the booster during re-entry.

The booster supporting this mission was B1061-4. It has already flown on three missions, thus, the CRS-22 mission marked its fourth flight.

Cargo Dragon 2

The CRS-22 mission was the second mission to the ISS for Cargo Dragon C208-2. Its first mission was the CRS-21, the first SpaceX’ launch under the CRS-2 contract.

Cargo Dragon 2 is 8.1 m (26.6 ft in) in height and 3.7 meters (12 feet) in diameter. Compared to the original Cargo Dragon, the upgraded spacecraft can and will automatically dock to the ISS. The old version had to be manually berthed by the Canadarm2.

The upgraded version of SpaceX’s Cargo Dragon spacecraft, Dragon 2, CRS-23 mission
The upgraded version of SpaceX’s Cargo Dragon spacecraft, Dragon 2 (Credit: NASA)

The Cargo Dragon 2 shares a similar design with the Crew Dragon intended to carry astronauts to the ISS and back to Earth. However, there are some differences. The Cargo Dragon 2 does not have SuperDraco abort engines, nor a life support system since there will be no human passengers on board. In the pressurized section, the seats and crew displays have been swapped for cargo racks. The environmental control system has been also reduced both in size and complexity.

Overall, the CRS-2 SpX-23 mission’s success criteria were successful deployment of the Cargo Dragon 2 to the dedicated orbit, its docking to the ISS, and recovery of the B1061-4 booster. All of them were met on this mission.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: