Dragon receives long-planned propulsive landing upgrade after years of development

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SpaceX announced a new capability for the Dragon spacecraft on Sept. 27 in the unlikely event of a parachute failure. Dragon now has built-in redundancy to propulsively land using its SuperDraco thrusters, saving the vehicle and potential crew from a rough landing or imminent danger. 

SpaceX introduced the concept of a propulsive landing Dragon over ten years ago. When SpaceX revealed Dragon 2, it was marketed as capable of propulsively landing anywhere on Earth and was initially designed to land exclusively with the SuperDracos. However, SpaceX ultimately pursued the use of parachutes as the main form of recovery for Dragon 2 missions.

Much has had to change with Dragon 2 since May 30, 2014, to make it the reliable crewed spacecraft we know it as today. Now, SpaceX has decided to bring back one of the main capabilities that was believed to have been left behind in development.

Rendering of Dragon 2 propulsively landing using eight SuperDraco thrusters. (Credit: SpaceX)

Why land a crewed capsule propulsively?

Rapid reusability was a major priority in SpaceX’s initial plans for flying Dragon. When returning from space, SpaceX planned for Dragon to light eight SuperDraco engines and propulsively slow the capsule’s velocity. When the velocity reached zero, the capsule would land on extendable landing legs on a designated landing pad. This action could have sped up the time it takes to refurbish Dragon and get it back on the launch pad.

Landing on a concrete landing pad on land rather than in the ocean has many advantages, particularly when it comes to the long-term reusability and refurbishment of Dragon capsules. When landing in the ocean, saltwater can corrode the aluminum body and carbon fiber bonds that Dragon is constructed of. Propulsively landing on Earth would have prevented invasive corrosion from occurring in the first place, making rapid reusability a much more achievable goal. 

What’s more, landing Dragon propulsively would’ve also been safer for the crew when exiting the spacecraft. Getting astronauts out of a capsule is an extended process, especially when they have been exposed to microgravity for extended periods of time. The motion of ocean waves and the process of retrieving Dragon from the water has proven to be quite lengthy, and landing on a solid pad on land would have allowed recovery teams to approach and egress the crew inside Dragon substantially quicker.

At the time of Dragon 2’s announcement and the reveal of Dragon’s capabilities to propulsively land, SpaceX was planning to ultimately use Dragon to land on the surface of Mars. This mission, dubbed “Red Dragon,” was technically possible, but SpaceX would later drop the plans in favor of Starship.

Mars has an atmosphere that is much less dense and more thin than Earth’s, meaning that parachutes are much less useful for landing. In the case of Red Dragon, Mars’ thin atmosphere meant that Dragon would have needed to propulsively land on the surface without the use of parachutes. With plans for Red Dragon in place and knowing that propulsive landings would be a necessity for future missions to Mars, SpaceX elected to pursue propulsive landings on Earth as well.

Rendering of Red Dragon propulsively landing on the surface of Mars. (Credit: SpaceX)

Why Dragon’s propulsive landing plans were canceled

Certifying a spacecraft for flight involves a long and in-depth process before it is allowed to reach orbit. These safety measures exponentially slowed the progress of a Red Dragon mission launching to Mars, even without crew. When NASA decided not to fund Red Dragon for a possible Mars sample return mission, SpaceX retired the Red Dragon mission and focused on further developing Dragon 2 for missions on Earth.

SpaceX began submitting bids for NASA’s Commercial Crew Program with a design for a crewed spacecraft featuring a powerful thruster system planned to double as a launch escape abort system. After proving Dragon 1’s ability to reach the International Space Station (ISS), SpaceX was selected by NASA to produce a crewed spacecraft for the Commercial Crew Program — which would eventually become Dragon 2.

While Dragon 2 and its involvement with the Commercial Crew Program differed from Red Dragon, the idea of propulsively landing Dragon was not immediately canceled after SpaceX’s contract was awarded. It was initially planned that, in the case of an issue with the propulsive landing sequence, precise water landings using two drogue parachutes and four main parachutes would become a backup plan. Months later, however, it was announced that SpaceX had switched its choice of landing system, and was now pursuing water landings via parachutes rather than land landings with the SuperDraco engines.

With parachutes now serving as Dragon’s main landing system, propulsively landing Dragon was no longer a main focus of Dragon 2’s development. It was later revealed that NASA desired a higher “loss of crew” reliability rating for Dragon and felt more comfortable with a parachute landing system than a propulsive landing system. NASA also believed that the small openings in Dragon’s heat shield for the four extendable landing legs could lead to the quick formation of hotspots during reentry, potentially leading to the break up of the vehicle. 

Returning to propulsive landings

In March 2019, SpaceX completed Demonstration Mission-1 (DM-1), during which Crew Dragon (the crewed variant of Dragon 2) successfully flew to the ISS and back without any significant problems. Following the mission, Elon Musk, when asked about propulsively landing Dragon, mentioned that it was “contingent upon NASA review and approval.” 

Just over a month after DM-1’s success, Crew Dragon C204 experienced an anomaly during a SuperDraco firing test. This anomaly resulted in the complete loss of the vehicle, which likely led to widespread delays with any plans SpaceX had for propulsively landing Dragon. Outside of SpaceX, it was assumed the anomaly marked the end of any plans for propulsive landings of Dragon.

Today, Crew Dragon is known to be an extremely reliable and well-tested vehicle — flying 15 successful crewed missions to the ISS and other low-Earth orbits and suffering little to no issues with its parachute landing system. During the Crew-9 pre-launch briefing, NASA announced that Dragon now had the capability to activate its SuperDraco engines and perform a propulsive landing if a failure of the parachutes were to occur. Should an anomaly with the parachutes occur, the four main parachutes would be cut and Dragon would ignite its eight SuperDraco engines to slowly perform a propulsive splashdown. NASA stated that such a landing would be “tolerable” for any crew inside Dragon.

This new propulsive landing system was available for the first time on Crew-7 in August 2023 and has been functional on all private SpaceX missions since then, and is expected to be used for future NASA ISS crew missions.

(Lead image: SpaceX testing Dragon’s eight SuperDraco’s during a hover test in 2015. Credit: SpaceX)

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