SpaceX Approaches Key Survival Test for Manned Missions
By Dr. Gary Deel
Faculty Director, School of Business, American Military University
Tomorrow, Elon Musk’s space logistics company SpaceX is scheduled to perform one of the final tests of its Crew Dragon capsule for manned missions to and from low-Earth orbit.
The SpaceX-designed Crew Dragon capsule on Saturday will undergo a test of its inflight abort system, one of its final tests before its maiden voyage with actual astronauts onboard.
The last time the United States had its own means of transporting astronauts into space was the Space Shuttle program that was retired in 2011. Since then, NASA has been relying on Russian Soyuz rockets to get astronauts into orbit and back to Earth. However, the Russian space agency, Roscosmos, has been steadily raising prices, reaching a peak of more than $80 million per seat in 2015.
NASA Has Promoted the Privatization of Routine Space Transport Missions with Commercial Companies
In recent years NASA has promoted the privatization of routine space transport missions through contracts with commercial space logistics companies. So far, this model has worked fairly well. Private sector partners such as SpaceX, Boeing, and Orbital ATK have been able to launch into space payloads such as new satellites and supplies for the International Space Station (ISS) with greater efficiency and lower costs than the government space program, saving American taxpayers time and money.
Competition in the commercial space launch industry has also led to critical leaps in technological innovation, such as SpaceX’s revolutionary recoverable/reusable first stage boosters.
Now, the government looks to the same partners to transport its astronauts. NASA awarded contracts to both SpaceX and Boeing to become the first companies to ferry astronauts between Earth and space, including to the ISS.
Because space rockets are little more than controlled bombs, if something were to go wrong with a rocket at any point during its ascent, the crew capsule must be able to break away from the rocket and escape before it could be destroyed by a catastrophic explosion. This is commonly referred to as an inflight abort system, and it was actually a standard feature on most of the early launch vehicles, including the famous Mercury, Gemini, and Apollo rockets.
The Space Shuttle Had No Such Escape System Due to Design Challenges
When NASA designed the Space Transport System (also known as the Space Shuttle), an inflight abort or escape system was not included due to challenges of designing such a system into the vehicle itself. However, NASA learned a catastrophic lesson when the Space Shuttle Challenger’s main fuel tank ruptured and exploded on ascent during a launch in 1986. The explosion destroyed the vehicle and killed all seven astronauts on board.
So one of the requirements of manned space launch vehicles today is that they be equipped with an inflight abort system capable of carrying the astronaut capsule to safety in the event of a critical failure.
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Most past inflight abort systems were “tractor” escape systems. These usually came in the form of an abort tower mounted on top of the astronaut capsule. The tower was equipped with high-powered rockets capable of pulling the crew capsule away from the launch vehicle if a problem arose. The tower was then jettisoned after ascent was complete.
However, Space X — and its competitor Boeing for that matter — have both decided to eschew the tractor method in favor of a “pusher” approach. With this method, instead of a tower on top of the capsule, rockets are installed at the bottom of the capsule that “push” it up and away from the booster in the event of a failure.
One of the advantages of the “pusher” system over the “tractor” system is that it eliminates a potential point of failure in the launch sequence. If an abort tower were to fail to detach from a crew capsule, it could compromise the success of the mission. But with a “pusher” system there is no need to discard any extra equipment inflight. The “pusher” system also allows the inflight abort system to be recovered with the capsule upon re-entry, which means that the system is reusable, unlike a launch abort tower, which generally is not recovered after it is jettisoned.
SpaceX and Boeing Are Using Liquid Fueled Rockets to Power Their Inflight Abort Systems
SpaceX and Boeing are also using liquid-fueled, due to their simplicity and relative safety as a contingency system.
However, the key disadvantage to solid rockets is that they can’t be throttled or shut off. Once they are ignited, they burn until their fuel is exhausted, regardless of need and direction. With liquid rocket motors, the propulsion can be adjusted as needed. Also, with thrust vectoring an escaping capsule can actually steer itself away from danger and into a safe descent and landing trajectory.
So tomorrow, as part of the NASA safety testing process, SpaceX will launch its Crew Dragon capsule atop a Falcon 9 rocket. At about a minute and a half into the flight, when the rocket is somewhere between eight and 17 miles (14 and 28 kilometers) in altitude, mission control will trigger the inflight abort system.
If All Goes Well, the Capsule Will Separate and Make its Way to a Safe Water Landing
If all goes well, the capsule will separate from the booster and make its way to a safe water landing in the Atlantic Ocean near its launch site at the Cape Canaveral Air Force Station. The booster itself will be unable to maintain flight control after the separation of the capsule due to aerodynamic instability, so it is expected to break up and fall harmlessly into the ocean.
Assuming the test is successful, SpaceX estimates that it should be able to launch the first American astronauts to the ISS within a few months’ time after remaining tests and checklists have been completed.
SpaceX plans to provide livestream coverage of the launch on its website.
About the Author
Dr. Gary Deel is a Faculty Director with the School of Business at American Military University. He holds a JD in Law and a Ph.D. in Hospitality/Business Management. He teaches human resources and employment law classes for American Military University, the University of Central Florida, Colorado State University and others.