Falcon 9 First Booster Landing (2015): Reusable Rockets

The first landing of a Falcon 9 booster took place on 21 December 2015, when the American company SpaceX launched 11 satellites and then flew the rocket’s first stage back to land upright at Cape Canaveral, Florida. It was the first time the main stage of an orbital-class rocket had returned intact to a landing pad after a launch to orbit. The achievement made rocket reusability, long discussed but rarely practised, a working reality.

Background: throwaway rockets

Since the first satellites of the late 1950s, nearly all launch vehicles have been expendable: each stage falls into the sea or burns up after a few minutes of use. Building a new rocket for every flight is one of the main reasons spaceflight has been so expensive.

The US Space Shuttle, first flown in 1981 as described in the article on STS-1, was partly reusable. Its orbiter and solid rocket boosters flew again, but the boosters had to be fished from the ocean and extensively refurbished, and the external tank was discarded. The shuttle never achieved the low costs once hoped for.

SpaceX was founded by the entrepreneur Elon Musk in 2002 with the declared aim of cutting launch costs, and recovering rocket stages was part of its plan from early on. The company’s Falcon 9 first flew in 2010. Its first stage, powered by nine Merlin engines, was designed so it could restart some engines on the way down and steer with grid fins and cold-gas thrusters.

Early attempts

Between 2012 and 2014 SpaceX tested vertical take-off and landing with a prototype called Grasshopper and its successor, F9R Dev1, which hopped to heights of up to about a kilometre. On real missions, Falcon 9 stages then performed controlled descents onto the ocean surface.

In January and April 2015 SpaceX tried to land boosters on an unmanned barge, which the company calls an autonomous spaceport drone ship, in the Atlantic. Both stages reached the ship but crashed or toppled. On 28 June 2015 a Falcon 9 carrying cargo to the International Space Station broke up about two minutes after launch, grounding the rocket for six months.

The night of 21 December 2015

The return-to-flight mission, known as Flight 20, used an upgraded version of the rocket, later called Falcon 9 Full Thrust, with more powerful engines and super-chilled propellants. It lifted off from Space Launch Complex 40 at 20:29 Eastern Standard Time (01:29 UTC on 22 December) carrying 11 ORBCOMM OG2 satellites.

About two and a half minutes after launch, the first stage separated. It flipped around, fired three engines to reverse course back towards the coast, then made a re-entry burn to slow down in the thicker atmosphere. A final burn of a single engine brought it down onto Landing Zone 1, a pad built on the site of the former Launch Complex 13. The booster touched down roughly ten minutes after lift-off, its sonic booms heard along the Florida coast.

The upper stage meanwhile placed all 11 satellites into orbit, so the mission was a complete success. Crowds at SpaceX’s headquarters in Hawthorne, California, watched the live webcast and cheered. The landed booster never flew again; it was later put on display outside the company’s headquarters.

Firsts and fair comparisons

Only a month earlier, on 23 November 2015, the company Blue Origin had landed its New Shepard booster after a suborbital hop to just over 100 km. That was also a significant milestone. However, an orbital first stage separates much higher and far faster, at several times the speed of sound, which makes recovery considerably harder.

Falcon 9 was also not the first craft to land vertically using rocket power: the Apollo lunar modules and experimental vehicles such as the McDonnell Douglas DC-X in the 1990s did so. The December 2015 flight was the first to combine a rocket landing with an operational orbital launch.

Legacy: reuse becomes routine

On 8 April 2016 a Falcon 9 booster landed on a drone ship for the first time. On 30 March 2017 a previously flown booster launched the SES-10 satellite, the first reflight of an orbital-class first stage. Within a few years, landing and reusing boosters had become standard practice for SpaceX, with individual boosters flying more than 20 times.

Reusability helped SpaceX dominate the commercial launch market and fly missions far more often than any previous launch provider. Other organisations in the United States, China and Europe began developing reusable rockets of their own.

Timeline

• 2002: Elon Musk founds SpaceX.
• 2010, 4 June: Falcon 9 makes its first flight.
• 2015, January and April: Two attempts to land a booster on a drone ship fail.
• 2015, 28 June: A Falcon 9 breaks up during a cargo flight to the ISS.
• 2015, 23 November: Blue Origin lands its suborbital New Shepard booster.
• 2015, 21 December: Falcon 9 Flight 20 launches 11 ORBCOMM satellites and lands its first stage at Landing Zone 1.
• 2016, 8 April: First successful Falcon 9 landing on a drone ship.
• 2017, 30 March: A landed booster flies again, launching SES-10.

Why it matters

The December 2015 landing showed that the most expensive part of an orbital rocket could be brought back intact. It turned reusability from an aspiration, pursued since the pioneering work of figures like Robert Goddard, into an everyday part of spaceflight, changing the economics of reaching orbit.