Featured image: NASA
Lift Off Time
|CST-100 Starliner Orbital Flight Test 2|
|United Launch Alliance (ULA)|
|Atlas V N22|
|Space Launch Complex 41 (SLC-41), Cape Canaveral Space Force Station, Florida, United States|
|13,200 kg (29,100 lb)|
Where is the spacecraft going?
|It will rendezvous with the ISS, ~400 km low Earth orbit (LEO) at a 51.6° inclination|
Will they be attempting to recover the first stage?
|No, this is not a capability of ULA|
Where will the first stage land?
|It will crash into the Atlantic Ocean|
Will they be attempting to recover the fairings?
|The Atlas V N22 has no fairings|
Are these fairings new?
How’s the weather looking?
This will be the:
|– 2nd launch of the Atlas V in the N22 configuration |
– 73rd orbital launch attempt of 2021
– 145th ULA mission
– 88th Atlas V mission
Where to watch
|Official livestream (if available)|
What does all this mean?
Boeing is preparing to repeat the first Orbital Flight Test of their Starliner spacecraft, which failed to dock with the International Space Station in 2019 following an issue with the spacecrafts Mission Elapsed Time (MET) clock. The spacecraft will launch atop ULA’s Atlas V N22 rocket, and will dock to the Harmony forward port of the ISS 24 hours later. OFT-2 will demonstrate Starliner’s capability to fly and dock to the ISS.
The rocket was scheduled to launch on August 4th, but an issue with valves meant the rocket had to be rolled back into the factory for further checks.
The OFT-2 mission
Boeing is planning to repeat the first Orbital Flight Test of their Starliner spacecraft, which failed to dock with the International Space Station in December 2019 with it’s OFT-2 mission. During the first mission, the Atlas V rocket launched successfully, but just 31 minutes into flight an error with the MET clock forced an abort to the ISS and sent the spacecraft into an incorrect orbit. It was later announced that the MET clock was offset by 11 hours. NASA and Boeing both attempted to correct the position of the spacecraft but burned too much fuel in the process, meaning rendezvous with the ISS impossible. The spacecraft reentered the atmosphere 3 days later, successfully demonstrating landing capabilities as it touched down at White Sands Space Harbor in New Mexico.
Boeing announced its plans to repeat the Orbital Flight Test (OFT-2) in early 2020. NASA accepted the plans to redo the test but at no additional cost to American taxpayers, meaning there was an estimated out-of-pocket cost of $410 million. Boeing and NASA originally targeted March 29, 2021 for the launch of OFT-2, however this has shifted several times since then.
OFT-2 Mission Objectives
The OFT-2 mission is expected to last six days, during which time Starliner will show docking and undocking capabilities with the ISS and land back in the United States. It will take the spacecraft just over 24 hours to reach the ISS, where is will then demonstrate autonomous rendezvous and docking. The spacecraft will remain docked to the ISS for 5 days, undocking on August 5th and landing back on Earth, at the White Sands Missile Range, just a few hours later. On the way to the ISS, the Starliner capsule will carry 200 kg (440 lb) of supplies and test equipment, simulating future missions that will have astronauts and cargo on board. On the return journey it will carry 260 kg (573 lb).
To make way for the arrival of Starliner, the Crew Dragon Endeavour, which was docked to the Harmony forward docking port of the ISS relocated to the Harmony zenith docking port on 21 July 2021.
The Boeing CST-100 Starliner spacecraft is a reusable crew capsule designed to take passengers to the ISS and other LEO destinations, manufactured by Boeing for NASA’s Commercial Crew Program. CST stands for Crew Space Transportation and the 100 stands for 100 km – the height of the Kármán line. The spacecraft has been designed to remain in orbit for up to seven months and can be reused for up to ten missions. Although it is being paired with an Atlas V for the OFT-2 mission, it is also compatible with the Delta IV, Falcon 9, and Vulcan Centaur rockets.
The spacecraft is split into two main sections, the crew module and the service module. The crew module is 4.56 m (15 ft) in diameter, for reference this is larger than the Apollo command module and smaller than the Orion capsule. It is capable of holding a crew of up to seven people, however for NASA missions to the ISS, it will carry four crew members and small cargo. The crew module is the only part that will survive reentry. Boeing modified the Starliners docking system design following the first orbital test flight. Now a hinged reentry cover will provide extra protection during the capsules atmospheric reentry.
The service module is where the propellant tanks and thrusters for orbital maneuvering, and the launch abort motors are. Four Areojet Rocketdyne RS-88 engine will be used for the launch escape system. The solar cells are also located on the bottom of the service module and on top of the micro-meteoroid debris shield, providing more than 2.9 kW of electricity.
Starliner lands using parachutes and a set of airbags, making it the first orbital capsule to land on solid ground in the US. Two drogue chutes are deployed at 9 km in altitude, before the trio of main chutes is deployed at 3.6 km. The heat shield is jettisoned at 1.5 km in altitude, after which the six airbags are inflated. These airbags ensure a soft landing on the ground, but are also useful in an abort situation as they will provide buoyancy when landing on water. There are five landing sights across the western United States, which allows the Starliner 450 landing opportunities across the year.
The first crewed flight (Boe-CFT) was initially scheduled for the summer of 2019, pending a successful first orbital test flight. The flight is now planned for the end of 2021, though this could slip into early 2022. The mission will fly three NASA astronauts, Barry Willmore, Michael Fincke, and Nicole Anuapu Mann to the ISS.
The Atlas V N22
The Atlas V is an expendable medium lift launch system and a member of the Atlas rocket family. The rocket has flown 87 times since it’s inaugural flight on August 21, 2002, and is one of the most reliable launch vehicles in the world, having no complete failures. OFT-2 is the second Atlas V flight without a payload fairing and with a dual-engine Centaur upper stage. This upper stage uses two RL 10 engines, which is required for all Starliner flight as a means of providing a launch trajectory that allows safe abort at any point during the mission.
An Atlas V in the N22 configuration supports this mission. The first number indicates the payload fairing diameter in meters. Normally this is 4 or 5, but as previously mentioned, this the second Atlas V flight to go without fairings, thus this configuration is N. The second number indicates the number of strap-on Solid Rocket Boosters (SRBs), which in this case is two. The final number is the amount of RL-10 engines on the Centaur Upper Stage, which is also two.
The Atlas V uses a Common Core Booster (CCB) as the first stage. It is powered by a single RD-180 engine, which burns a highly purified form of kerosene called Rocket Propellant-1 (RP-1) and liquid oxygen (LOx). The CCB has a Specific Impulse (ISP) of 311.3 s at sea level and 337.8 s in vacuum, and provides 3,827 kN (860,300 lbf) of thrust. The CCB will burn for 253 seconds before crashing into the Atlantic ocean.
Two GEM-63 solid rocket boosters (SRBs) assist the first stage’s Common Core Booster during lift off. These are 20.1 m (66 ft) tall and run on QDL-4, HTPB, 19% Aluminum. They have an ISP of 279 s and provide 1,234 kN (277,590 lbf). The booster stage starts with ignition of the CCB’s RD-180 engine system, followed by SRB ignition, which will burn for 97.6 seconds.
The Atlas V second stage is the Centaur Upper Stage, which uses a pressure stabilized propellant tank design and cryogenic propellants. Two RL10A-4-2 engines power this configuration of the Atlas V, opposed to the normal one RL-10C-1-1 engine. The RL10A-4-2 is an expander cycle turbo-pump fed engine which runs on liquid hydrogen (LH2) and liquid oxygen (LOx). The stage will burn for ~700 seconds, has an ISP of 451.0 s and provides 99.1 kN (22,300 lbf) of thrust.