As part of a media teleconference for its second operational flight test (OFT-2) for the Orion spacecraft, representatives of The Boeing Company assured members of the press that the rapid success of Space Exploration Technologies Corporation’s (SpaceX) Dragon spacecraft is not affecting them in any way. Boeing and SpaceX are both a part of the National Aeronautics and Space Administration’s (NASA) commercial crew program which aims to develop a sustained American capability of conducting crewed flights to the International Space Station (ISS).
Boeing Assures It Is Ready To Conduct Crucial Flight Test Of Crewed Spacecraft
As part of her prepared remarks, Boeing’s vice president and deputy general manager of Space and Launch, Ms. Michelle Parker explained the measures that her company has undertaken to ensure that the Starliner vehicle is ready to take to the skies later this month. This mission, dubbed OFT-2, was set to take off in July last year but got delayed as an accident on the ISS made the space station unavailable for docking. Then, a month later in August, Boeing stepped down from the launch attempt, and it explained that valve problems on the vehicle made the launch unfeasible. Now, nine months after disocvering the problem, Boeing is confident that the Starliner propulsion valves are free from fault. Ms. Parker, who was the chief engineer for testing the vehicle after the launch delay, outlined that: Later on in the event, Marcia Dunn of the Associated Press attempted to steer the conversation away from the technical side of things to the motivational angle and asked the Boeing representatives whether they were frustrated by watching SpaceX regularly launch crews to the ISS. If you recall when we first experienced the issue in august we immediately set up an integrated investigation team. So that was all team members, NASA, Boeing and ourselves involved to look at all possible causes with the goal of understanding the issue, mitigating it, and returning to the launch pad safely and as efficiently as possible, and I am glad to be able to say that the team has accomplished this goal and we’re ready to go. As you may recall we followed a rigorous process to make sure we understood the behavior; we went through a fault tree analysis; we looked at all the potential causes, used facts and data to eliminate all the potential causes, and hone in on the root cause. So this remains the cause that we talked about in about the October timeframe, of this combination within the valve of the nitrogen tetraoxide or the NTO, ambient moisture, and the aluminum housing of the valve. So you need all three of those aspects to come together in order for the first two, the NTO and the ambient moisture, to react to create nitric acid, which then reacts with the aluminum housing of the valve causing corrosion products and those corrosion products then result in preventing the valve motion which is a very very small motion like 30 mil (millimeter) of motion and just the presence of those corrosion products can hinder that progress. So that’s the root cause that we’ve had. We’ve completed testing both on and off the vehicle. So we did return the vehicle to the factory as you know. We did a lot of testing on service module two with the valves that had experienced this issue to understand the behavior and really hone in on what we were seeing. We have also been able to remove those valves since then and do disassembly of valves, a valve that was stuck, a valve that was intermittent, and a valve that wasn’t stuck. And what we saw within those valves were these corrosion products as we’ve mentioned. So we were able to confirm the presence of those products in the way that I just said. We’ve also done off-vehicle material testing, and we’ve done off-vehicle valve testing with valves that had not been on the spacecraft at White Sands to confirm the generation of these corrosion products that these three constituents present. And in that testing also we have exposed those valves to the environmental conditions that the valves had seen and also those environmental conditions that we expect to be seen on OFT-2 and confirmed that our mitigation methods are appropriate. So again as I talk a little bit about the mitigation that we’ve put in place, and Mark has touched on this also. As I mentioned in order to have this reaction, you need these three components, the NTO, the moisture the ambient moisture in the air, and the aluminum housing. Without those three components, you don’t get the reaction. So without the moisture, if you can eliminate the moisture from the valve, you won’t have this reaction and it won’t lead to corrosion. So we’ve done a number of things for the mitigation, including a dry purge of the valves, so the valves have compartments through which we’ve got CN2 purging the valves to prevent any moisture from getting into the valve. We’ve also sealed out a potential moisture path in the electrical connector to ensure that we don’t get any ambient humidity through that path. So those two things will prevent the moisture from getting into the valve to start that reaction at all. And then in addition we’ve loaded the NTO later, Mark mentioned the vehicle is loaded, we do that loading later in the flow so there’s less time of exposure of the NTO. And we’ve added operationally we’ve added cycling of the valves every two to five days post-load until the time that we launch to ensure that the valves remain operational. We’ve been doing that cycling, we’ve done that successfully, we’ll continue to do that. The last cycle will be on the 17th and then during the nominal countdown launch procedure on the 19th we’ll cycle the valves again. In response, Ms. Parker stated: She was joined by Boeing’s vice president and program manager for the CST-100 Starliner program, Mr. Mark Nappi, who stressed that safety was paramount for his company. According to him: Finally, NASA’s associate administrator of the Space Operations Mission Directorate Ms. Kathryn Leuders clarified that Boeing and SpaceX were part of the same team and that her agency was grateful to SpaceX for having provided it with the ability to conduct detailed safety investigations while having the option of conducting human spaceflight simultaneously. As Ms. Leuders explained: The NASA-Boeing OFT-2 mission is set to take to the skies from the agency’s facilities in Florida on May 19th. If successful, it will pave the way for the pair to conduct the first crewed test for the vehicle after Starliner returns to Earth.
