How It Works

Spacex Dragon capsule

The first-ever commercial spacecraft to leave and return to Earth explained


When the NASA Space Shuttle was retired in 2011, several different companies competed to become NASA’S new choice for cargo and crew transporta­tion to the Internatio­nal Space Station (ISS) – and possibly beyond.

In 2006 and 2008 NASA awarded the private company Spacex two contracts totalling roughly $2 billion (£1.59 billion), paving the way for the Dragon capsule to complete its first successful orbit and re-entry in December 2010.

Powered by a combinatio­n of solar panels and an advanced lithium battery, the Dragon capsule is large, allowing for the transporta­tion of up to seven crew members or up to six tonnes of cargo. It uses 18 liquid-fuel thrusters equipped with dinitrogen tetroxide and mono methyl hydrazine to manoeuvre while in orbit. Like NASA’S Orion, the conical shape of the Dragon capsule is deemed the best for Earth re-entry, while also allowing for a sizeable interior.

One of its defining features is a variant of NASA’S Phenolic-impregnate­d Carbon Ablator (PICA) heat shield. Spacex’s PICA-X heat shield advances on NASA’S design in a number of places, notably its significan­tly reduced cost and added reusabilit­y. This allows it to be used hundreds of times, whereas NASA’S currently does not survive its flight. This shield protects the capsule as it re-enters Earth’s atmosphere at several thousand degrees and keeps the interior close to room temperatur­e.

Three oversized parachutes slow its descent to Earth, although it can operate on only one if the other two should fail. The capsule has to land in water. The last flight of Dragon’s first iteration touched down in the Atlantic Ocean off the coast of Florida after ferrying supplies to the ISS on 7 March 2020. Resupply missions – as well as missions delivering crew – will now be taken over by Dragon 2.

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