Boeing’s Starliner spacecraft is preparing for two major flight tests before the end of the year, which will pave the way for the spacecraft’s first crewed flight in 2020. The capsule is being developed under NASA’s Commercial Crew Program to provide transportation services to and from the International Space Station.
NASA provided an official update on Boeing’s flight test dates last Friday. Starliner’s pad abort test is currently scheduled for no earlier than November 2nd, with the Orbital Flight Test (OFT) occurring no earlier than December 17th.
The pad abort test will see a Starliner capsule perform the abort sequence that would be necessary if there were to be a problem with the launch vehicle on the pad.
November’s abort test will occur from a test stand at the White Sands Missile Range in New Mexico.
During the flight, Starliner will be tasked with executing a complicated set of maneuvers in short succession.
The flight will begin with the spacecraft’s four primary abort engines firing to pull the vehicle away from the pad. During the ascent, smaller attitude control thrusters will also be used to maintain stability.
After approximately four and a half seconds of burn time, the four abort engines will shut down. The attitude control system will continue to operate as Starliner coasts to apogee.
Once near apogee, the attitude control system will flip the Starliner around and the drogue parachutes will be deployed. Deployment of the three primary parachutes will follow shortly after that.
Starliner’s service module will then be jettisoned – leaving just the crew module to complete the remainder of the test.
Next up will be the jettison of the crew module’s heat shield. This step is necessary to make way for airbag inflation. Starliner’s airbags are used to cushion the impact at touchdown.
If successful, the test will conclude with a soft touchdown in the New Mexico desert – demonstrating a critical safety system for Starliner.
The capsule’s abort system is also capable of performing an escape maneuver while being lifted into space by the launch vehicle – a major improvement compared to the Space Shuttle which had very limited abort capabilities.
After the pad abort test, the next major item on Starliner’s plate will be the Orbital Flight Test (OFT). OFT is the uncrewed demonstration mission of Starliner to the International Space Station.
The mission will be the first time that Starliner is launched into orbit.
Like all of its currently manifested missions, Starliner will be launched atop a United Launch Alliance Atlas V rocket during the OFT flight.
The launch will occur from Space Launch Complex 41 at Cape Canaveral Air Force Station in Florida.
An Atlas V in the N22 configuration will be used for the Starliner missions. The N stands for “No fairing,” the first 2 represents the number of solid rocket boosters, and the final 2 indicates that the Atlas will be flying with a dual-engine Centaur upper stage.
While a dual-engine Centaur second stage has flown into space numerous times in the past, this will be the first time that one flies on an Atlas V rocket.
The single-engine Centaur configuration did not provide adequate thrust to fly the required flight profile for Starliner. Consequently, an additional RL10 engine was added.
One particularly unusual aspect of the Starliner missions is that the spacecraft will be placed into a suborbital trajectory by the Atlas V, rather than being inserted directly into orbit.
“United Launch Alliance is flying a very unique trajectory specifically for Starliner. The booster is flying both a flatter trajectory and at lower thrust than uncrewed Atlas V missions to both limit G loading on crew members and enable an abort during all phases of powered ascent to orbit,” said a Boeing spokesperson.
“This is also the reason a dual engine Centaur upper stage is used on Starliner flights. While Centaur will push Starliner most of the way to orbit, the unique flight trajectory makes it necessary for Starliner’s Orbital Maneuvering and Attitude Control system to conduct an Orbital Insertion burn to stabilize the orbit and put itself on a rendezvous trajectory with the International Space Station.”
During the ascent, the Atlas V’s Emergency Detection System (EDS) will closely monitor the performance of the rocket. If something were to go wrong during a crewed flight, the system is capable of commanding an abort if necessary. However, the EDS system will be in a passive mode during the OFT flight – meaning that it will not be capable of executing an abort during the test mission.
This is to ensure that the EDS system does not interfere with the other aspects of the mission if it was to be triggered erroneously. Once the EDS has been validated during the uncrewed OFT, it will then be ready for active use during future crewed flights.
After Starliner reaches orbit during OFT, it will then attempt its first docking with the International Space Station. The spacecraft will stay at the station for a few days before undocking and returning to Earth.
Boeing has not officially confirmed the preferred landing site for the OFT mission, but the capsule will likely either touchdown at the U.S. Army’s Dugway Proving Ground in Utah or the White Sands Missile Range in New Mexico.
Starliner is designed to be able to target a number of landing locations in case there is inclement weather at one of the locations.
By landing on land instead of the ocean, Starliner avoids the corrosive saltwater environment – aiding its reusability. The capsules are being designed to fly up to 10 times.
While the OFT mission is currently scheduled for no earlier than December 17th, there are still several important milestones ahead before the launch can occur.
“Boeing, NASA and United Launch Alliance teams will be conducting a full Integrated Day of Launch Test (IDOLT) ahead of the Orbital Flight Test. The event will include all prelaunch activities similar to what will occur on the actual day of launch including fuel loading, pad operations and a full countdown to T-0,” said a Boeing spokesperson.
Additionally, the traditional prelaunch Flight Readiness Review (FRR) is also expected to determine if everything is go to proceed with the OFT mission.
One major preflight milestone was accomplished on Wednesday, with the command and service modules of Starliner for the OFT mission being mated together.
— Boeing Space (@BoeingSpace) October 17, 2019
Assuming that all goes according to plan with the pad abort test and OFT, the Crewed Flight Test (CFT) will be the final test flight before Starliner is certified for regular crew rotation missions.
CFT will be a crewed demonstration mission to the Space Station. The flight will feature three crew members, NASA astronauts Michael Fincke and Nicole Mann, along with Boeing test pilot Christopher Ferguson.
The CFT flight was originally supposed to feature a two-week stay at the Space Station. The duration was later extended to be a full-duration crew rotation mission – to account for delays with the Commercial Crew Program.
Thus, the CFT mission will now last for several months.
If all goes well with the upcoming test flights, there is a chance that CFT could occur in the first half of 2020.
— Christopher Ferguson (@Astro_Ferg) August 21, 2019
During the operational crew missions which will commence after CFT, Starliner will be capable of transporting up to four crew members to the Space Station.
In the meantime, NASA continues to rely on the Russian Soyuz rocket and spacecraft to carry its astronauts to the orbiting laboratory. This has come at an expensive price – with Russia charging NASA as much as $85 million per seat.
NASA is expected to purchase one final Soyuz seat while it awaits for its Commercial Crew Program to come online.