SpaceX CRS-21

T+00:00: Liftoff
T+01:18: Maximum aerodynamic pressure
T+02:30: First stage main engine cutoff (MECO)
T+02:34: Stage separation
T+02:41: Second stage engine start
T+06:37: First stage entry burn begins
T+08:38: Second stage engine cutoff (SECO)
T+08:38: First stage landing on drone ship
T+11:49: Dragon separation
T+12:35: Dragon nose cone open sequence begins

BioAsteroid is an experiment designed to test the infrastructure and tools needed for asteroid, lunar, and Martian rock biomining. It will use microorganisms (the bacterium S. desiccabilis and the fungus P. simplicissimum) to extract metals from L-chondrite, testing the possibility to use this technique to obtain resources that will allow long-term and long-distance human space exploration and extraterrestrial settlements.

Hemocue is a test of the system for white blood cell testing on the Moon and Mars. The systems were developed under Earth's gravity, and still need to be tested in zero-g's.

The Brain Organoid experiment is a continuation of the first Brain Organoid experiment. Its goal is to validate the first round of experiments and to continue the research recorded during those first tests. The program studies the early developed human brain, its movements in microgravity, and can help address and create better models of neurodegenerative disorders.

Cardinal Heart is a continuation of a previous experiment. This experiment will study cardiomyocytes in human heart tissue and its reaction to a zero-g environment. NASA Astronaut Kate Rubins was present for the experiment on station a few years ago, and she said that, paraphrased, few things on station make her gasp, but this is one thing that does.

Subsa-Brains studies the effects of micrometeorites and space junk and the damage they can cause, as well as the process to repair the tissue, called brazing, and if it still works in a zero-gravity environment.

Three-Dimensional Microbial Monitoring (3DMM) is a project that aims to construct a three-dimensional map of bacteria and metabolites that are present at various locations throughout the ISS, and determine how the spaceflight environment affects the various species identified.

Monoclonal Crystal Research in Microgravity (MCRM) is a protein crystallization experiment by the American pharmaceutical company Bristol Myers Squibb. NASA astronauts will study the crystallization of monoclonal antibodies in space, with the aim of improving drug formulation and delivery for patients on Earth. Monoclonal antibodies are lab-created proteins designed to interact with specific targets, called antigens. Monoclonal antibodies are used in the treatment of numerous diseases, including cancer.[23]

Rodent Research-23 (RR-23), will study the effects of spaceflight on the eyes, specifically on the structure and function of the arteries, veins, and lymphatic vessels that are needed to maintain vision.

Student Spaceflight Experiments Program: The Student Spaceflight Experiments Program (SSEP) has 27 experiments manifested as part of Mission 14A.[24]

The CRS-21 pressurized capsule carries a variety of other research including studies on how space conditions affect the interaction between microbes and minerals.[20]

Beginning with returning capsules or lifting bodies under the CRS-2 contract, NASA reports major hardware (failed or expended hardware for diagnostic assessment, refurbishment, repair, or no longer needed) returning from the International Space Station. The SpaceX CRS-21 mission ended on 14 January 2021 with re-entry into Earth's atmosphere and splash down near the western coast of Florida with 2,002 kg (4,414 lb) of return cargo. This cargo included:[16]

Treadmill Data Avionics Unit: Failed avionics unit that supports the treadmill, a critical item returning to the ground following the on-orbit replacement with a good spare.

Carbon Dioxide Removal Assembly (CDRA) Air Selector Valve: Critical degraded valve returning for repair and refurbishment to support the carbon dioxide removal capability on-orbit.

Nitrogen Oxygen Recharge System (NORS) Tank: Depressurized tank capable of flying oxygen or nitrogen, and will be utilized for future on-orbit demand in 2021.

Rodent Research Habitats and Transporters: Live rodents from the Rodent Research-23 (RR-23) mission and used habitats and transporters that support future research missions and analysis.

Minus Eighty Laboratory Freezer for ISS (MELFI) Electronics Unit: Failed cold stowage item requiring ground repair to enable future cold stowage missions.

Thermal Amine Bulk Water Save Valve: Failed valve that supports efficient usage of the Thermal Amine system returning to ground for repair, will help inform robustness of similar valve design on Orion capsule.