The Crew Dragon Launch Abort System is designed to propel the SpaceX Crew Dragon spacecraft away from a failing launch vehicle. It is equipped with 8 SuperDraco engines, each capable of generating 71 kN of thrust. The abort system has several modes, or procedures for performing an abort in different phases of flight, including a pad abort, an in-flight abort, and the ability to use the abort system to fly into a lower than expected orbit should a failure occur late in flight. __TOC__

Design

Traditionally, spacecraft like

Apollo Apollo is one of the Twelve Olympians, Olympian deities in Ancient Greek religion, ancient Greek and Ancient Roman religion, Roman religion and Greek mythology, Greek and Roman mythology. Apollo has been recognized as a god of archery, mu ...

and

Soyuz Soyuz is a transliteration of the Cyrillic text Союз (Russian language, Russian and Ukrainian language, Ukrainian, 'Union'). It can refer to any union, such as a trade union (''profsoyuz'') or the Soviet Union, Union of Soviet Socialist Republi ...

have utilized solid-fueled "puller" launch escape systems, with the main spacecraft beneath a protective fairing attached to the escape system. Once in space, the escape system and the fairing are jettisoned, with the spacecraft's mode of abort switched to using its orbital maneuvering thrusters or upper stages. Crew Dragon, however, has its abort system permanently attached to the sides of the spacecraft. Part of the reasoning behind this design is that it was originally planned to land dragon propulsively using the launch abort system. These plans were dropped after skepticism from

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

and the cancellation of

SpaceX Space Exploration Technologies Corp., commonly referred to as SpaceX, is an America, American space technology company headquartered at the SpaceX Starbase, Starbase development site in Starbase, Texas. Since its founding in 2002, the compa ...

's Red Dragon capsule. However, the capability was introduced on Crew-8, though only in the event of a parachute failure. Additionally, the ability to keep the abort system attached to the rocket throughout the entire ascent rather than jettisoning the launch escape system after stage separation allows for an abort capability in all stages of flight, increasing crew safety. Crew Dragon's "trunk", or cargo bay, also plays an important role in the abort sequence. Rather than leaving the trunk with the rocket like

, Dragon keeps the trunk attached during an abort for aerodynamic stability.

History

Pad Explosion

On 20 April 2019,

Crew Dragon C204 Crew Dragon C204 was part of Crew Dragon flight vehicle SN 2-1 (sometimes incorrectly called C201) manufactured and operated by SpaceX and used by NASA's Commercial Crew Program. Used in the uncrewed Demo-1 mission, it was launched atop a Falc ...

was destroyed in an incident while testing its SuperDraco engines. A video leaked shortly after the incident shows the capsule exploding on a launch mount.

and

confirmed the explosion and stated that there were no injuries. Vertical Ball check valve

Following an investigation, SpaceX stated that the explosion was the result of a faulty valve. During a nominal ignition sequence, valves keeping helium inside COPVs (Composite Overwrapped Pressure Vessels) are opened, causing the helium to flow through one-way check valves into the propellant tanks, pushing the fuel into the

combustion chamber A combustion chamber is part of an internal combustion engine in which the air–fuel ratio, fuel/air mix is burned. For steam engines, the term has also been used for an extension of the Firebox (steam engine), firebox which is used to allow a mo ...

. In this incident, however, the one-way oxidizer valve had allowed nitrogen tetroxide (NTO) to leak back through the helium tube. When the helium valve was opened, the "blobs" of NTO inside the helium line were accelerated at high speeds, slamming into and nearly instantaneously destroying the one-way oxidizer valve. The internal titanium components of the destroyed valve were then exposed to the NTO, resulting in combustion and the loss of the vehicle.

In-Flight Abort Test

On 19 January 2020,

conducted a test of Crew Dragon's launch abort system. After a successful liftoff, the launch abort sequence was initiated 1 minute and 26 seconds into flight. Crew Dragon C205 successfully separated with the

Falcon 9 Falcon 9 is a Reusable launch system#Partial reusable launch systems, partially reusable, two-stage-to-orbit, medium-lift launch vehicle designed and manufactured in the United States by SpaceX. The first Falcon 9 launch was on June 4, 2010, an ...

rocket, with the rocket breaking up seconds later under the intense aerodynamic forces of max-q. After separating the trunk, Crew Dragon reached an

apogee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...

of 42 kilometers before splashing down in the

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

Abort modes

The Crew Dragon has multiple abort modes for different phases of flight, each with its own landing zones and procedures. As the flight progresses, SpaceX

mission control A mission control center (MCC, sometimes called a flight control center or operations center) is a facility that manages space flights, usually from the point of launch until landing or the end of the mission. It is part of the ground segment ...

calls out switches between abort modes. For typical launches, recovery zones are placed along the 51.64-degree

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

of the ISS, and can be targeted with higher levels of precision than spacecraft such as Orion and Shenzhou due to the throttling abilities of the SuperDraco engines. The recovery areas for a 2a type abort are along the East Coast of the United States and

The Maritimes The Maritimes, also called the Maritime provinces, is a region of Eastern Canada consisting of three provinces: New Brunswick, Nova Scotia, and Prince Edward Island. The Maritimes had a population of 1,899,324 in 2021, which makes up 5.1% of ...

on Canada's Atlantic coast, with a 2b abort landing the Crew Dragon capsule near

Nova Scotia Nova Scotia is a Provinces and territories of Canada, province of Canada, located on its east coast. It is one of the three Maritime Canada, Maritime provinces and Population of Canada by province and territory, most populous province in Atlan ...

and the 2c and 2d abort modes resulting in a landing in Western Ireland. 1a and 1b aborts result in landings near the American East Coast.

References