Falcon 9 flight 20 (also known as Orbcomm OG2 M2) was a

Falcon 9 Falcon 9 is a partially reusable medium lift launch vehicle that can carry cargo and crew into Earth orbit, produced by American aerospace company SpaceX. The rocket has two stages. The first (booster) stage carries the second stage and pay ...

space launch that occurred on 22 December 2015 at 01:29:00 UTC (21 December, 8:29:00 pm local time). It was the first time that the first stage of an orbital rocket made a successful return and vertical landing. The successful landing of the first stage at

Landing Zone 1 Landing Zone 1 and Landing Zone 2, also known as LZ-1 and LZ-2 respectively, are landing facilities on Cape Canaveral Space Force Station for recovering components of SpaceX's VTVL reusable launch vehicles. LZ-1 and LZ-2 were built on land le ...

, near the launch site, was the result of a five-year technology development program to develop a

reusable launch system A reusable launch vehicle have parts that can be recovered and reflown, while carrying payloads from the surface to outer space. Rocket stages are the most common launch vehicle parts aimed for reuse. Smaller parts such as rocket engines and boos ...

and came on a

flight test Flight testing is a branch of aeronautical engineering that develops specialist equipment required for testing aircraft behaviour and systems. Instrumentation systems are developed using proprietary transducers and data acquisition systems. D ...

that followed the primary launch mission. Following separation of the second stage, SpaceX conducted the eighth of its controlled booster descent tests of the spent first stage, the first in which the descent target location was on land, and also the first ever successful landing. Prior to this flight, SpaceX's two previous attempts at a vertical landing and booster recovery ended in failure to recover the rocket. The success of flight 20 marked a significant milestone en route to the company's goal of creating a reusable rocket system that would significantly reduce the cost of launching payloads into orbit. Falcon 9 flight 20 was the first launch of the substantially upgraded

Falcon 9 Full Thrust Falcon 9 Full Thrust (also known as Falcon 9 v1.2, with variants Block 1 to Block 5) is a partially reusable medium-lift launch vehicle, designed and manufactured by SpaceX. Designed in 2014–2015, Falcon 9 Full Thrust began launch operations ...

version of the Falcon 9

launch vehicle A launch vehicle or carrier rocket is a rocket designed to carry a payload ( spacecraft or satellites) from the Earth's surface to outer space. Most launch vehicles operate from a launch pads, supported by a launch control center and ...

. It carried 11

Orbcomm-OG2 Orbcomm is a family of low Earth orbit communications satellites, operated by the United States satellite communications company Orbcomm. , 51 such satellites have orbited Earth, with 50 still continuing to do so. Satellite types Orbcomm-CD ...

satellites to

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

orbit. The launch was also notable as it was the first SpaceX launch following the catastrophic failure of a

Falcon 9 v1.1 Falcon 9 v1.1 was the second version of SpaceX's Falcon 9 orbital launch vehicle. The rocket was developed in 2011–2013, made its maiden launch in September 2013, and its final flight in January 2016. The Falcon 9 rocket was fully designed ...

launch vehicle's second stage on

Falcon 9 Flight 19 SpaceX CRS-7, also known as SpX-7, was a private American Commercial Resupply Service mission to the International Space Station, contracted to NASA, which launched and failed on June 28, 2015. It disintegrated 139 seconds into the flight a ...

in June 2015.

Launch schedule history

SES SES, S.E.S., Ses and similar variants can refere to: Business and economics * Socioeconomic status * Scottish Economic Society, a learned society in Scotland * SES, callsign of the TV station SES/RTS (Mount Gambier, South Australia) * SES S.A., ...

announced in February 2015 that it would provide the payload on the first launch of the revised-design

(also called Falcon 9 v1.2 ). At the time, SES expected its

SES-9 SES-9 is a geostationary communications satellite operated by SES S.A. It was launched from Cape Canaveral SLC-40 by a Falcon 9 Full Thrust launch vehicle on 4 March 2016. Satellite description SES-9 is a large communications satellite operat ...

geostationary communications satellite would launch by September 2015. SES kept the decision despite the loss of the launch vehicle and payload of another SpaceX mission in June 2015, but postponed the launch until late 2015. On 16 October 2015, after considering all options, SpaceX announced a change:

Orbcomm ''ORBCOMM'' is an American company that offers industrial Internet of things (IoT) and machine to machine (M2M) communications hardware, software and services designed to track, monitor, and control fixed and mobile assets in markets including ...

's 11 OG2 satellites would be the payload on the return-to-flight launch of the redesigned Falcon 9 instead of SES-9. The Orbcomm payload with its lower orbit would allow SpaceX to test relighting the second-stage engine, a capability required to successfully put the heavier SES-9 on a geostationary orbit. The launch was delayed to mid-December or later, while SES-9 was scheduled to follow within a few weeks. A required pre-launch static-fire test was initially scheduled for 16 December 2015, but a few issues emerged with the new processes required for the colder propellants for the launch vehicle and the related ground support equipment. The test was successfully carried out on 18 December 2015, which resulted in a launch delay of one day to 19 December 2015 (local time). The launch was subsequently delayed an additional day after statistical analysis indicated a somewhat higher probability of recovering the booster on the later date.

New launch vehicle

The

launch vehicle used on flight 20 had a number of significant modifications from the previous

vehicle. These included: * increased second stage tank length and propellant volume * larger

Merlin 1D vacuum Merlin is a family of rocket engines developed by SpaceX for use on its Falcon 1, Falcon 9 and Falcon Heavy launch vehicles. Merlin engines use RP-1 and liquid oxygen as rocket propellants in a gas-generator power cycle. The Merlin eng ...

engine nozzle * larger and stronger interstage with revised stage-separation mechanism * revised

grid fin Grid fins (or lattice fins) are a type of flight control surface used on rockets and bombs, sometimes in place of more conventional control surfaces, such as planar fins. They were developed in the 1950s by a team led by and used since the 197 ...

design to support the continuation of the

Falcon 9 booster controlled-descent and landing tests The Falcon 9 first-stage landing tests were a series of controlled-descent flight tests conducted by SpaceX between 2013 and 2016. Since 2017, the first stage of Falcon 9 missions has been routinely landed if the rocket performance allowed it, a ...

, and ultimately, the operational

Reusable Falcon 9 SpaceX is private spaceflight, privately funding the development of Orbital spaceflight, orbital spacecraft, launch systems that can be reusable launch vehicle, reused many times, in a manner similar to the reusability of aircraft. SpaceX has ...

launch system * upgraded structure in the landing legs, also to support the reusable development program and objectives * upgraded first stage structure and

octaweb Falcon 9 v1.1 was the second version of SpaceX's Falcon 9 orbital spaceflight, orbital launch vehicle. The rocket was New product development, developed in 2011–2013, made its Falcon 9 Flight 6, maiden launch in September 2013, and its Falcon ...

engine support structure * denser

liquid oxygen Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an app ...

and

RP-1 RP-1 (alternatively, Rocket Propellant-1 or Refined Petroleum-1) is a highly refined form of kerosene outwardly similar to jet fuel, used as rocket fuel. RP-1 provides a lower specific impulse than liquid hydrogen (LH2), but is cheaper, is s ...

propellants through the use of

subcooling The term subcooling (also called undercooling) refers to a liquid existing at a temperature below its normal boiling point. For example, water boils at 373 K; at room temperature (293 K) the water is termed "subcooled". A subcooled liqui ...

, refrigeration below the typical temperature of previous Falcon 9 launch conditions. * first stage booster can reach

low Earth orbit A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never mor ...

as a single stage if not carrying the upper stage and a heavy satellite.

Launch and on-orbit test

Flight 20 was launched on 22 December 2015 at 01:29 UTC (21 December, 8:29 pm local time).

Second stage re-ignition

Following successful launch and deployment of the OG2 satellites, the Merlin Vacuum (1D) second-stage engine successfully re-ignited, demonstrating its capability to launch SES-9 into geostationary transfer orbit. The engine burn de-orbited the second stage as planned for a destructive

re-entry Atmospheric entry is the movement of an object from outer space into and through the gases of an atmosphere of a planet, dwarf planet, or natural satellite. There are two main types of atmospheric entry: ''uncontrolled entry'', such as the entr ...

, preventing it from becoming space debris.

Payload

Falcon 9 Flight 20 carried 11

second-generation satellites, which will provide enhanced ORBCOMM messaging capabilities, increased data capacity, and automatic identification systems (AIS) service. All 11 satellites were successfully deployed by the Falcon 9 second stage, beginning approximately 14 minutes after takeoff. All 11 satellites successfully checked in with ground control stations. The satellites were placed by the launch vehicle "within a fraction of a degree in inclination and in altitude of the intended orbit, "and by 9 January 2016, were in the middle of on-orbit testing, while executing propulsion maneuvers that had spread the 11 satellites over a orbital arc. Initial ORBCOMM customer message traffic began to be tested by late January 2016. Satflare reported in February 2016 that one of the 11 flight 2 satellites will reenter Earth's atmosphere in late-February 2016. The satellite manufacturer,

Sierra Nevada Corporation Sierra Nevada Corporation (SNC) is an American, privately held aerospace and national security contractor specializing in aircraft modification and integration, space components and systems, and related technology products for cybersecurity and ...

, completed checkout work and handed all 11 satellites off to ORBCOMM in early March 2016.

Post-mission landing

SpaceX performed a controlled-descent test on the rocket's first stage — the eighth propulsive return test of the series. For the first time, SpaceX was able to vertically land and successfully recover the first stage. Earlier tests had proven the high-altitude deceleration and atmospheric re-entry portions of the test protocol, but no landing attempt had previously been successful, including two attempts earlier in 2015 to land a first stage on a

floating landing platform A floating launch vehicle operations platform is a marine vessel used for launch or landing operations of an orbital launch vehicle by a launch service provider: putting satellites into orbit around Earth or another celestial body, or recovering ...

. The entire controlled-descent through the atmosphere and landing attempt is an arrangement that is unusual for other

s. The flight test was planned for the twentieth Falcon 9 launch, even after the manifested payload was switched from SES-9 to the 11-satellite Orbcomm OG-2 payload.SpaceX preparing for Static Fire test on first Full Thrust Falcon 9 First Stage
24 October 2015, accessed 26 October 2015 The test was scheduled for and successfully carried out on 21 December 2015, when the first stage landed intact at

. SpaceX decided not to fly the

B1019 A Falcon 9 first-stage booster is a reusable rocket booster used on the Falcon 9 and Falcon Heavy orbital launch vehicles manufactured by SpaceX. The manufacture of first-stage booster constitutes about 60% of the launch price of a single expe ...

again. Rather, the rocket was moved a few miles north to

Launch Pad 39A Launch Complex 39A (LC-39A) is the first of Launch Complex 39's three launch pads, located at NASA's Kennedy Space Center in Merritt Island, Florida. The pad, along with Launch Complex 39B, were first designed for the Saturn V launch vehicle. Ty ...

, recently refurbished by SpaceX at the adjacent

Kennedy Space Center The John F. Kennedy Space Center (KSC, originally known as the NASA Launch Operations Center), located on Merritt Island, Florida, is one of the National Aeronautics and Space Administration's (NASA) ten field centers. Since December 1968 ...

, to conduct a static fire test. This test aimed to assess the health of the recovered booster and the capability of this rocket design to fly repeatedly in the future. The historic booster was eventually displayed outside SpaceX headquarters in

Hawthorne, California Hawthorne is a city in the Los Angeles metropolitan area, located in southwestern Los Angeles County, California. It is part of a seventeen-city region commonly called the South Bay. As of the 2020 US census, Hawthorne had a population of 88, ...

Evaluation of the recovered first stage

On 31 December 2015, SpaceX announced that no damage had been found on the stage and that it was ready to perform a

static fire Launch vehicle system tests assess the readiness of a launch system to safely reach orbit. Launch vehicles undergo system tests before they launch. A wet dress rehearsal (WDR) and a more extensive static fire tests a fully assembled launch vehicl ...

again.Falcon 9 back in the hangar at Cape Canaveral. No damage found, ready to fire again.
Elon Musk, via Twitter, 31 December 2015, accessed 2 January 2016 SpaceX had initially moved the booster to their hangar at LC-39A, but they moved the stage to SLC-40 — the pad from which it was launched — on 12 January 2016. On 15 January 2016, SpaceX conducted the static fire test on the recovered booster, obtaining good overall results except for one of the outer engines experiencing thrust fluctuations. Elon Musk reported that this may have been due to debris ingestion.Falcon 9 booster fires again at Cape Canaveral
Spaceflight Now, 16 January 2016, accessed 18 January 2016 In February 2016, SpaceX President and

COO COO or coo may refer to: Business * Certificate of origin, used in international trade * Chief operating officer or chief operations officer, high-ranking corporate official * Concept of operations, used in Systems Engineering Management Process ...

Gwynne Shotwell Gwynne Shotwell ( Rowley; born November 23, 1963) is an American businesswoman and engineer. She is the president and chief operating officer of SpaceX, an American space transportation company, where she is responsible for day-to-day operation ...

indicated that some unspecified modifications to the stage design would occur as a result of the booster's post-flight evaluation and static fire.

Display

In August 2016, the returned first stage was put on permanent display on a stand outside SpaceX headquarters in

Live coverage

SpaceX live coverage of the launch and landing included cheering crowds and tours of the SpaceX manufacturing and launch facilities. ''

The Atlantic ''The Atlantic'' is an American magazine and multi-platform publisher. It features articles in the fields of politics, foreign affairs, business and the economy, culture and the arts, technology, and science. It was founded in 1857 in Boston, ...

'' technology editor Robinson Meyer called the scripted broadcast "a way of treating a rocket launch not like a dry engineering procedure, but like some combination of the

Macy's Thanksgiving Day Parade The Macy's Thanksgiving Day Parade is an annual parade in New York City presented by the U.S.-based department store chain Macy's. The Parade first took place in 1924, tying it for the second-oldest Thanksgiving parade in the United States with ...

and the Super Bowl". Upon the unprecedented first stage landing, a SpaceX engineer announced "The Falcon has landed", reminding audiences of the first Apollo landing.

References

External links

SpaceX video of full mission

Musk pre-launch backgrounder on Falcon 9 Flight 20
22 December 2015
Round-trip rocket flight gives SpaceX a trifecta of successes
Spaceflight Now, 22 December 2015
Elon Musk's SpaceX returns to flight and pulls off dramatic, historic landing
''Washington Post'', December 2015 {{Orbital launches in 2015 2015 in spaceflight Falcon 9 2015 in Florida Rocket launches in 2015