On Sept. 1, 2016, a SpaceX rocket exploded on the launch pad at Cape Canaveral, immolating the $300 million commercial satellite on board and causing a scramble among Kennedy Space Center’s first responders to contain the damage. The rocket detonated during a routine pre-flight test after the rocket had been fueled—no one was injured.
But from the ashes of that 2016 mishap came a showdown between the new pioneer of space, SpaceX, versus the old vanguard of the cosmos, NASA. NASA-run programs always filled the tanks of rockets before astronauts boarded. SpaceX’s plan called on filling the tanks after boarding the astronauts inside the Dragon capsule.
Which would prevail?
New Working With Old
Even though it was not their payload, NASA program managers worried. The same rocket system would fly the space agency’s astronauts—and it just detonated on the launch pad. Under the same circumstances, the crew would only have an unproven rocket-powered abort system to rescue them. The safety of the astronauts depended on NASA and SpaceX getting this answer right.
On Friday NASA said that the pair have worked out their two-year-long dispute. Next April, NASA astronauts Bob Behnken and Doug Hurley will board the spacecraft about two hours before launch, and using SpaceX’s recommended method, the astronauts will sit inside the capsule during fueling. Then, the Falcon 9 rocket and Dragon Capsule will deliver the astronauts to and from the International Space Station.
But there are some conditions that need to be met before SpaceX gets the go ahead. According to NASA, there are now “additional verification and demonstration activities” that SpaceX must complete before NASA certifies April’s crewed demonstration flight.
“To make this decision, our teams conducted an extensive review of the SpaceX ground operations, launch vehicle design, escape systems and operational history,” said Kathy Lueders, manager of NASA’s Commercial Crew Program.
The launch pad explosion is the focus of the concern, and NASA has its collective eye on the root cause: a pressurized helium canister located inside the fuel tank.
The gas inside these Composite Overwrapped Pressure Vessels (COPVs) is used to pressurize the liquid oxygen tank. The COPV is made of aluminum and wrapped in protective carbon fiber composite. A slight buckle in the metal liner would provide a pocket for the supercooled oxygen to collect, trapped there when the tank becomes pressurized.
One possibility is that liquid oxygen could have pooled in such a deformation and became solid. Damage to the carbon fiber liner then propagated and caused it to burst, starting a chain reaction that annihilated the rocket and its payload.
SpaceX scrutinized these tanks in early 2016, switching the order of rockets launching so that they could check out what the company called “bad trends” in a number of helium pressurization system bottles. SpaceX also decided to start building them in-house, rather than using an Alabama-based contractor.
SpaceX’s post-explosion investigation took place in Texas, where engineers tested the fuel loading process at the company’s McGregor test facility near Waco. They loaded the cryogenically cooled helium into tanks, testing them until failure. Within weeks the company said it could “re-create a pressure tank failure entirely through helium loading conditions. These conditions are mainly affected by the temperature and pressure of the helium being loaded.”
NASA is now looking at SpaceX’s new loading process to ensure that lessons have been learned. There are now “five crew loading demonstrations of the Falcon 9 Block 5 [that] will be critical to final certification of this plan,” NASA said in a statement.
The Final Hurdle
But even then, SpaceX won’t be cleared for launch.
“After these conditions have been met, NASA will assess any remaining risk before determining that the system is certified to fly with crew,” NASA added.
If the tests and added scrutiny goes well for SpaceX, the COPVs will be loaded with helium and verified to be in a stable configuration before astronauts arrive at the launch pad. The ground crews will leave launchpad 39A and 38 minutes before liftoff the rocket will activate its launch escape systems. Only then will SpaceX mission control staff start loading the kerosene fuel and liquid oxygen.
“The countdown and launch preparations can be stopped automatically up to the last moment before launch,” NASA said. “In the unlikely event of an emergency at any point up to and after launch, the launch escape systems will allow the astronauts to evacuate safely.”
For NASA, this is an unprecedented moment—accepting a substational risk of doing things a new way. For SpaceX, it’s a critical test to prove that their breakneck speed and bargain prices are safe and sustainable for more ambitious crewed flights, for NASA or other paying customers.
How this plan plays out will have a great bearing on the timeline of the launch. With Boeing suffering delays and no Soyuz flights ordered from Russia, the pressure is mounting for SpaceX and NASA to start launching astronauts from U.S. soil.
“Safety for our personnel was the driver for this analysis,” said NASA’s Lueders, “and the team’s assessment was that this plan presents the least risk.”
Previously published by: Popular Mechanics USA