Boeing Starliner vs SpaceX Crew Dragon: Battle for the ISS

The Boeing CST-100 Starliner and the SpaceX Crew Dragon are both spacecraft designed to transport astronauts to and from the International Space Station (ISS). They were developed as part of NASA’s Commercial Crew Program to ensure that the United States has reliable access to space. Here’s a detailed comparison of their launches to the ISS:
Spacecraft Overview
Boeing CST-100 Starliner:
Manufacturer: Boeing.
Capacity: Up to 7 astronauts.
Launcher: Atlas V rocket (provided by United Launch Alliance, ULA).
Design: Capsule design with a reusable crew module and disposable service module.
SpaceX Crew Dragon:
Manufacturer: SpaceX.
Capacity: Up to 7 astronauts (usually configured for 4 for ISS missions).
Launcher: Falcon 9 rocket (designed and manufactured by SpaceX).
Design: Capsule design with integrated trunk section for additional cargo.
Launch Sequence
Pre-Launch Preparations:
Starliner: Final checks and integration with the Atlas V rocket at ULA’s facilities. Astronauts are transported to the launch pad and board the spacecraft.
Crew Dragon: Final checks and integration with the Falcon 9 rocket at SpaceX’s facilities. Astronauts are transported to the launch pad in Tesla vehicles and board the spacecraft.
Launch Countdown:
Both spacecraft undergo rigorous checks and countdown procedures, including fueling of the rockets and verification of all systems.
Liftoff:
Starliner: Launched atop an Atlas V rocket from Cape Canaveral Air Force Station (now Cape Canaveral Space Force Station) in Florida.
Crew Dragon: Launched atop a Falcon 9 rocket from Kennedy Space Center in Florida.
Ascent and Orbit Insertion:
Both rockets follow a similar trajectory to reach low Earth orbit, but the specifics of their ascent profiles and timing differ based on their launch vehicles.
The first and second stages of the rockets separate, with the second stage completing the insertion into orbit.
Rendezvous and Docking with ISS
Orbital Maneuvers:
After reaching orbit, both spacecraft perform a series of maneuvers to rendezvous with the ISS. These maneuvers include phasing burns to align their orbit with the station.
Approach:
Both Starliner and Crew Dragon use automated systems to approach the ISS. They have manual override capabilities that allow astronauts to take control if necessary.
Docking:
Starliner: Uses the NASA Docking System (NDS) to autonomously dock with the ISS.
Crew Dragon: Also uses the NASA Docking System to autonomously dock with the ISS. The Crew Dragon features a sleek touchscreen interface for astronauts to monitor and control the process.
Stay at ISS and Return
Onboard Operations:
While docked, both spacecraft serve as additional living and working space for the crew. They can stay docked for several months, supporting long-duration missions.
Undocking and Return:
When the mission is complete, both spacecraft undock autonomously and perform deorbit burns to re-enter the Earth’s atmosphere.
Starliner: Lands on solid ground using parachutes and airbags, typically at one of several designated sites in the western United States.
Crew Dragon: Splashes down in the Atlantic Ocean or Gulf of Mexico, slowed by parachutes, and is recovered by SpaceX’s recovery vessels.
Key Differences
Launch Vehicle:
Starliner: Launched by Atlas V, a proven rocket with a long track record.
Crew Dragon: Launched by Falcon 9, known for its reusability and cost-effectiveness.
Landing:
Starliner: Designed for land-based recovery.
Crew Dragon: Designed for water-based recovery.
Development and Testing:
Starliner: Experienced delays and technical issues, including a notable uncrewed test flight in December 2019 where it failed to reach the ISS due to software issues.
Crew Dragon: Successfully completed several crewed and uncrewed missions to the ISS, including the historic Demo-2 mission in May 2020, which was the first crewed orbital launch from the U.S. since the Space Shuttle era.
Both spacecraft represent significant advancements in space travel, providing NASA with redundancy and ensuring that the U.S. maintains continuous human spaceflight capabilities.