SpaceX’s Crew Dragon Endeavour will begin its second mission Friday, with a crew of four astronauts on a long-duration trip to the International Space Station. Liftoff, atop a Falcon 9 rocket from Florida’s Kennedy Space Center, is expected at 05:49:02 EDT / 09:49:02 UTC on Friday, 23 April 2021.
The Crew-2 mission will see Endeavour carry NASA astronauts Shane Kimbrough and Megan McArthur, Thomas Pesquet of the European Space Agency (ESA) and Akihiko Hoshide of the Japan Aerospace Exploration Agency (JAXA) to join the Expedition 65 crew aboard the International Space Station (ISS). It will be the third crewed mission overall for SpaceX and its Crew Dragon vehicle following its Demo-2 flight last year and the Crew-1 mission which remains in orbit.
Background
SpaceX developed an initial version of the Dragon spacecraft under NASA’s Commercial Orbital Transportation Systems (COTS) program to provide cargo services to the Station. This version of Dragon first flew in December 2010 and went on to make 20 resupply runs to ISS under a Commercial Resupply Services (CRS) contract.
This version has now been retired, with the enhanced Dragon v2 spacecraft developed as part of the Commercial Crew Program, taking its place. This v2 Dragon can fly in the crewed configuration that is being used for Friday’s mission while an uncrewed version has also been developed to take over cargo missions under the second phase of CRS.
SpaceX was also one of two companies selected to carry US and international crews to the Station under NASA’s Commercial Crew program, with Boeing’s Starliner also chosen. The third spacecraft used for ISS crew rotation is Russia’s Soyuz.
Like the Space Shuttle before it, Crew Dragon is reusable – the first reusable human capsule launch and entry system in the world. The Crew-2 mission will mark the second flight to orbit for Endeavour, spacecraft C206, which flew the historic Demo-2 mission in May 2020.
The first crews to fly on a new Dragon v2 have the honor of choosing the craft’s name – with Endeavour’s being announced by her first crew shortly after she reached orbit on the Demo-2 mission. It was named specifically after and in honor of the Space Shuttle Endeavour, the last of NASA’s Space Shuttle orbiters to be built and the first spacecraft aboard which both of the Demo-2 astronauts flew.
Unlike the Shuttle, however, Dragon Endeavour is designed to remain in orbit for extended stays at the Space Station. Dragon Endeavour will arrive at the ISS while her sister ship Resilience, which launched last November with Crew-1, is still docked at the outpost. This will be the first time since Project Gemini in the 1960s that two US crewed missions have been in orbit at the same time and the first time in history that two US human spacecraft will be docked at the Station at the time.
The Dragon v2 fleet (both human and cargo versions) docks with the ISS using one of two International Docking Adaptors (IDAs) connected to a Pressurised Mating Adaptor (PMA) that formerly supported Space Shuttle missions. The IDAs, which convert the PMAs from the APAS-95 standard that was used by the Shuttle to the International Docking System Standard (IDSS) used by NASA’s Commercial Crew vehicles, were delivered on previous cargo Dragon missions.
Endeavour will initially dock to PMA-2/IDA-2 at the forward end of the Harmony/Node-2 module before being relocated to PMA-3/IDA-3 on the Harmony’s zenith, or space-facing, port during its stay.
Launch to docking timeline
Endeavour and her crew will ride to orbit aboard SpaceX’s semi-reusable Falcon 9 rocket. First flown in 2010, the two-stage Falcon 9 has completed over 100 successful launches in the last 10 years and quickly became a workhorse for the American space industry.
Pre-launch timeline:
| T- time to launch | Time (EDT/UTC) | Event |
| T-5hrs | 00:04 EDT / 04:49 UTC | Dragon IMU alignment & configuration for launch |
| T-4hrs 40mins | 01:09 EDT / 05:09 UTC | Go/No Go for Dragon propellant tank pressurization |
| T-4hrs 30mins | 01:19 EDT / 05:19 UTC | Dragon propellant tank pressurization |
| T-4hrs 25mins | 01:24 EDT / 05:24 UTC | Launch escape health checks |
| T-2hrs 35mins | 03:14 EDT / 07:14 UTC | Crew ingress begins |
| T-1hr 55mins | 03:54 EDT / 07:54 UTC | Dragon hatch closure for flight |
| T-45mins | 05:04 EDT / 09:04 UTC | Launch Director verifies go for propellant loading |
| T-42mins | 05:07 EDT / 09:07 UTC | Crew Access Arm retraction |
| T-38mins | 05:11:02 EDT / 09:11:02 UTC | Dragon Launch Escape armed |
| T-35mins | 05:14:02 EDT / 09:14:02 UTC | Falcon 9 propellant loading begins |
| T-17mins | 05:32:02 EDT / 09:32:02 UTC | Stage 2 RP-1 kerosene load complete |
| T-16mins | 05:33:02 EDT / 09:33:02 UTC | Stage 2 densified liquid oxygen loading begins |
| T-7mins | 05:42:02 EDT / 09:42:02 UTC | Merlin 1D chilldown begins |
| T-5mins | 05:44:02 EDT / 09:42:02 UTC | Dragon to internal power |
| T-4mins 30secs | 05:44:32 EDT / 09:44:32 UTC | Strongback retract to 88.5° |
| T-2mins 55secs | 05:46:07 EDT / 09:46:07 UTC | Stage 2 engine Thrust Vector Control gimbal checks |
| T-2mins | 05:47:02 EDT / 09:47:02 UTC | Propellant load complete; Falcon 9 to internal power |
| T-1min | 05:48:02 EDT / 09:48:02 UTC | Dragon enters countdown mode |
| T-45secs | 05:48:17 EDT / 09:48:17 UTC | Launch Director verifies GO for launch. |
| T-3secs | 05:48:59 EDT / 09:48:59 UTC | First stage Merlin 1D engine start commanded |
| T0 | 05:49:02 EDT / 09:49:02 UTC | LIFTOFF |
The Falcon 9 design has evolved significantly over its career, with the current Block 5 configuration – which SpaceX considers to be the final, definitive, version – having been introduced in 2018.
Falcon 9’s first stage, known as the booster, was designed to be recovered and re-used for multiple launches. Equipped with nine Merlin-1D engines, it powers Falcon 9 away from the launch pad and through the dense lower regions of Earth’s atmosphere. After releasing the second stage to continue on to orbit, the booster performs a series of additional engine burns to complete a soft landing either back at the launch site or aboard an Autonomous Spaceport Drone Ship (ASDS) positioned downrange along its flightpath.
Missions that carry lighter payloads to lower orbits typically feature the booster returning to the launch site, while heavier payloads or those bound for higher-energy orbits will use a drone ship recovery. Targeting a landing aboard the ASDS means that the booster does not need to make an additional boostback burn to change its course back towards the landing pad, meaning more fuel can be put towards the primary mission.
Crew-2 marks the second flight for booster 1061, which previously launched the Crew-1 mission last November. This is the first time a flight-proven booster has been used to launch a Crew Dragon mission. SpaceX will be aiming to recover the booster again following launch, with the ASDS Of Course I Still Love You positioned in the Atlantic Ocean to receive it after the second stage and Endeavour have been deployed towards orbit.
Falcon 9’s second stage has a single Merlin Vacuum (MVac) engine, which is a modified Merlin-1D optimised to perform more efficiently in the vacuum of space. After the first stage has boosted it through most of Earth’s atmosphere, the second stage takes over the job of injecting Dragon into orbit.
Launch timeline:
| T+ time since launch | Time (EDT/UTC) | Event |
| T0 | 05:49:02 EDT / 09:49:02 UTC | Stage 1a abort available |
| T+1mins 02secs | 05:50:04 EDT / 09:50:04 UTC | Max-Q |
| T+1min 14secs | 05:50:17 EDT / 09:50:17 UTC | Stage 1b abort available |
| T+2mins 35secs | 05:51:37 EDT / 09:51:37 UTC | Stage 2a abort available |
| T+2mins 36secs | 05:51:38 EDT / 09:51:38 UTC | Stage 1 shutdown |
| T+2mins 39secs | 05:51:41 EDT / 09:51:41 UTC | Stages 1/2 separation |
| T+2misn 47secs | 05:51:49 EDT / 09:51:49 UTC | Stage 2 ignition |
| T+7mins 27secs | 05:56:29 EDT / 09:56:29 UTC | Stage 1 entry burn |
| T+8mins 05secs | 05:57:08 EDT / 09:57:08 UTC | Stage 2b abort available |
| T+8mins 30secs | 05:57:32 EDT / 09:57:32 UTC | Stage 2c abort available |
| T+8mins 39secs | 05:57:42 EDT / 09:57:42 UTC | Stage 2d abort available |
| T+8mins 46secs | 05:57:49 EDT / 09:57:49 UTC | Stage 2e abort available |
| T+8mins 49secs | 05:57:51 EDT / 09:57:51 UTC | Stage 2 engine shutdown / orbit insertion |
| T+9mins 03secs | 05:58:05 EDT / 09:58:05 UTC | Stage 1 landing burn |
| T+9mins 31secs | 05:58:33 EDT / 09:58:33 UTC | Stage 1 landing |
| T+11mins 58secs | 06:01:00 EDT / 10:01:00 UTC | Dragon Endeavour separation from Stage 2 |
| T+13mins 02secs | 06:02:04 EDT / 10:02:04 UTC | Dragon nosecone open sequence begins |
Endeavour’s crew are in good hands with Falcon 9. It is an extremely reliable rocket, with only one in-flight failure across 112 orbital launches of the single-core Falcon 9 since its debut in 2010. This failure involved an earlier version of the rocket which disintegrated during ascent in 2015 after a composite overwrapped pressure vessel (COPV) broke free inside the second stage oxidiser tank. A second Falcon 9 was destroyed by an explosion during a pre-launch static fire test in 2016, due to a design flaw which caused the second stage COPVs to buckle and rupture while the rocket was being fueled.
In the unlikely event that something should go wrong with launch, Dragon is equipped with a launch abort system to carry the spacecraft and her crew to safety. This consists of eight liquid-propellant SuperDraco engines built into the sides of the Dragon capsule. If the onboard computer senses an emergency, or the abort system is activated manually, the capsule will separate and the engines will fire to propel it clear of the rocket.
Dragon has several abort modes: 1a and 1b during first stage flight would see Dragon splashdown off the eastern seaboard of the United States. Abort modes 2a through 2d cover different phases of second stage flight, with landing points on either side of the Atlantic Ocean, while mode 2e would account for a problem at the end of the second stage burn where Dragon could safely reach orbit under its own power.
Launch day operations will begin with a readiness briefing 5.5 hours before liftoff. Flight controllers will arrive on station half an hour later, and the process of preparing Endeavour for flight will commence with alignment of the spacecraft’s inertial measurement units (IMUs) and pressurisation of its propellant tanks.
The Endeavour atop the Falcon 9 at 39A. (Credit: Thomas Burghardt for NSF)
Following a weather briefing, the crew will don their spacesuits around four hours before the planned liftoff, followed about 40 minutes later by walkout to a waiting fleet of Tesla cars that will take them to the launch pad.
Upon their arrival at Launch Complex 39A, Endeavour’s crew will take a few moments to view their rocket before boarding the elevator that will take them to the crew access level. Ingressing Endeavour will begin about 2 hours 35 minutes before liftoff. Once the crew are in their seats, the seats will be rotated into launch position, with the hatch closed 1 hour and 55 minutes before launch.
Endeavour will remain at the Station until at least October, although it will undock and redock once to free up the forward port for other missions.
The Crew
The four astronauts who will fly aboard Crew-2 arrived at the Kennedy Space Center on Friday. Endeavour’s all-veteran crew is commanded by Shane Kimbrough, making his third trip to space. Kimbrough, 53, graduated from the US Military Academy and served in the US Army prior to joining NASA. He rose to the rank of Colonel.
After initially working in NASA’s aircraft operations division, Kimbrough was selected as an astronaut in 2004. His first mission was aboard the Space Shuttle Endeavour in 2008 for the STS-126 mission. During the 16-day flight, Kimbrough made two spacewalks as part of the effort to repair the solar alpha rotary joints (SARJs) of the Station’s truss structure.
Kimbrough’s second mission was a long-duration stay aboard the ISS from September 2016 to April 2017 as part of Expeditions 49 and 50, the latter of which he served as Commander for. On this mission, Kimbrough travelled to and from the Station aboard the Soyuz MS-02 spacecraft and made a further four spacewalks during his time on the outpost.
For Megan McArthur, 49, Crew-2 will be her second trip to space and her first visit to the International Space Station. A graduate of the University of California at Los Angeles with a doctorate in Oceanography from the University of California at San Diego, McArthur was selected as an astronaut in 2000. Her previous flight was aboard the highly-watched mission of the Space Shuttle Atlantis on STS-125: the final Hubble servicing mission, STS-125. During the 13 day flight, McArthur operated the Shuttle’s robotic arm, including both the capture and release of the Hubble telescope.
She holds the distinction of being the last human in history – per the current plan – to directly interact with Hubble, sending the physical command to release the observatory from the end of Atlantis’ Canadarm.
Yesterday was a whirlwind, but the good kind: Depart Houston! Arrive Kennedy! Rocket! Spaceship! pic.twitter.com/Ul22wnLHSC
— Megan McArthur (@Astro_Megan) April 17, 2021
With Crew-2, McArthur will also become only the fourth woman in history to pilot a US crewed space mission following Eileen Collins, Susan Still, and Pamela Melroy (current nominee for NASA’s Deputy Administrator) of the Shuttle era.
Thomas Pesquet, 43, of the European Space Agency’s astronaut corps, will make his second trip into space on this mission. Born in France, he earned his Master’s degree in engineering with a focus on spacecraft design and control from École nationale supérieure de l’aéronautique et de l’espace in Toulouse in 2001 and went to work that year as a spacecraft dynamics engineer for a remote sensing mission for GMV Innovating Solutions in Spain.
He worked at the Centre national d’études spatiales (CNES) – the French space agency – where he served as a research engineer on space mission autonomy before leaving for Air France’s flight training program, where he earned an Airline Transport Pilot License and worked for Air France as a commercial aviation pilot from 2006 to 2009.
In 2009, he officially joined ESA and completed basic astronaut training in November 2010. Pesquet participated in ESA’s CAVES underground course in 2011; in 2013, he served as a member of the support crew for NASA’s NEEMO 17 underwater mission.
He is a veteran of one previous long-duration visit to the International Space Station as a member of the Expedition 50 and 51 crews from 2016 to 2017 – launching and landing aboard Russia’s Soyuz MS-03.
The European Space Agency names each of their astronauts’ missions, separate from the overall flight they are participating in. Pesquet’s mission has been named “Alpha” after the star Alpha Centauri, which was the winning entry in a competition.
The final member of Endeavour’s crew is Akihiko Hoshide, of the Japan Aerospace Exploration Agency (JAXA). A veteran of two previous space missions, Hoshide, 52, graduated from Tokyo’s Keio University before earning a master’s degree in aerospace engineering at the University of Houston. Having joined Japan’s National Space Development Agency (NASDA – a precursor to JAXA) in 1992, he participated in the development of Japan’s H-II rocket and was later involved with JAXA’s astronaut program before being selected as an astronaut himself in 1999.
Hoshide’s first mission was aboard Space Shuttle Discovery during 2007’s STS-124 mission which delivered the pressurised section of the Japanese Experiment Module – Kibo – to the ISS. His second mission was a four-month stay aboard the Station in 2012 during Expeditions 32 and 33 – travelling to and from the outpost aboard Soyuz TMA-05M.
Thanks everybody for waiting for us at NASA Kennedy Space Center today! So happy to be here for launch, so honored to be part of the team, and so thrilled to see our own spacecraft & rocket! Now time to go to bed so we can sleep shift for our 6:11 am EST launch… pic.twitter.com/ZRBbItkhTU
— 星出 彰彦 (JAXA宇宙飛行士) (@Aki_Hoshide) April 16, 2021
Endeavour’s crew will join Russian cosmonauts Oleg Novitsky and Pytor Dubrov, and NASA’s Mark Vende Hei – who arrived aboard Soyuz MS-18 earlier this month – as members of the Expedition 65 crew aboard the International Space Station. Upon docking, Endeavour’s arrival will mark the second time two Japanese astronauts are aboard the Station together when Aki joins Soichi Noguchi, who is part of the soon-to-leave Crew-1 mission.
Shortly arriving at the Station, Aki Hoshide will take command of the outpost, only the second time a Japanese astronaut has commanded the ISS.
(lead image: Crew Dragon Endeavour atop the Falcon 9 rocket less then 24 hours before launch. Credit: Thomas Burghardt for NSF)