SpaceX Crewed Dragon: Pressing home the advantage
With all three Commercial Crew partners providing a status update at the Kennedy Space Center (KSC) this week, SpaceX have outlined their path towards launching a crew on their Dragon spacecraft in 2015. With the advantage of already flying cargo missions on a near-human rated Dragon, SpaceX are leading the drive to return domestic crew launch capability to the United States.
SpaceX Crewed Path:
The latest Dragon spacecraft is currently preparing for its third flight to the International Space Station (ISS) under their Commercial Resupply Services (CRS) contract with NASA.
This next flight (CRS-2/SpX-2) – scheduled to launch at 10:10am on March 1 from Cape Canaveral – will be carrying critical supplies to the orbital outpost, ahead of completing its mission by providing what is now the rare commodity of downmass capability for returning hardware and experiments.
The mission is pending a final go-ahead from NASA, after SpaceX briefed the agency’s Mike Suffredini and William Gerstenmaier on what is now understood to be a confirmed root cause of the Engine 1 failure during Falcon 9’s previous launch with the CRS-1 (SpX-1) Dragon.
The first stage issue related one of the nine Merlin 1C engines, after – it is understood – the fuel dome above the nozzle ruptured. The engine did not explode, but did cause the fairing that protects the engine from aerodynamic loads to rupture and fall away from the vehicle due to the engine pressure release.
According to SpaceX’s Commercial Crew project manager, Garrett Reisman, some details into the root cause of the failure will be revealed to the public in the coming weeks. However, due to the proprietary nature of SpaceX’s hardware, only SpaceX – and their customer, NASA – will ever get to see the full overview from the joint CRS-1 Post-Flight Investigation Board report.
The results are also likely to include details of the second issue, relating to the upper stage that failed a propellant mass check at SECO-1, resulting in its secondary payload passenger – an Orbcomm satellite – being left in an unworkable orbit, prior to deorbiting.
The key to the continued confidence NASA have in SpaceX comes via the success of the primary mission objectives, as Dragon behaved well on orbit and suffered no ill effects of its launch vehicle having a tantrum during the ride uphill.
With the Dragon that is already flying being a vehicle that is partly crew-rated already, SpaceX are working a parallel process to their current campaigns to complete the drive that will fully enable their spacecraft to safely carry astronauts to the ISS.
This process is currently in the Commercial Crew integrated Capability (CCiCAP) stage, maturing from the Commercial Crew Development (CCDev) process that has resulted in three companies earning NASA money to bring their spacecraft up to spec for NASA astronauts.
However, as reported by NASASpaceflight.com’s Pete Harding, it is unlikely that any NASA astronauts will get to ride on a commercial vehicle until late 2016 – as shown in ISS Flight Planning Integration Panel (FPIP) charts (available on L2) on the current plan for ISS crew rotations using what are tagged as USCVs (US Commercial Vehicles).
According to the FPIP chart, the first USCV will launch in December 2016, for a docking to the Node 2 Forward port – via the use of an ISS Docking Adapter (IDA) attached to PMA-2. A Soyuz spacecraft is also pencilled in for the same date as a back-up (all USCVs on the chart have Soyuz back-ups assigned, should the USCV not be available).
The USCV will carry four crewmembers, meaning that once it docks to the ISS, the crew of the station will be boosted to seven – allowing significant extra research activities to be performed. However, one of the crewmembers on the USCV will be Russian – just as one American crewmember will continue to be rotated on the Soyuz.
This is done in order to ensure that a US crewmember is always present on the ISS, even when no USCV is docked to the station. It is not known at this point whether the seat on the USCV will be provided to Russia in exchange for a US seat on the Soyuz.
Per the commercial crew update briefing, only SpaceX have said they will be able to conduct crew launches as early as 2015 – meaning the crew will be selected in-house, as opposed to being assigned by NASA.
This “crew ability” date is based on the milestones laid out past the current range of objectives currently provided through to the end of the CCiCAP phase in 2014, allowing for a notional forward roadmap based on the projections per company.
“We laid out a plan that gets us to flying the first test flight in the middle of 2015, followed by flying a crew to the ISS by the end of 2015,” noted Mr Reisman. “That would be done with a test pilot crew.
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“(However,) because this would be done prior to final (NASA) certification, we are not legally allowed to use NASA astronauts to be part of that test pilot crew – so it will be SpaceX test pilots for that crew. We’re not selling tickets, so don’t call our toll-free number.”
Mr Reisman, a two-time Shuttle astronaut, intimated he is not interested in becoming one of the test crew.
In order to get to the promised land of being the first commercial company to launch humans to the ISS, several key elements of the Dragon spacecraft require development – not least the Launch Abort System (LAS).
Dragon sports a series of eight liquid SuperDraco engines, built into the side walls of the Dragon spacecraft, capable of producing up to 120,000 pounds of axial thrust to drive the Dragon away from its failing launch vehicle.
Advantages of the SuperDraco liquid thruster – when compared to the traditional use of solid propellent – includes how the engine can be put through a series of throttling ranges, in turn allowing for redundancy, with SpaceX claiming they could lose one of the eight abort engines and still recover the vehicle and crew successfully. The engines can also be restarted multiple times.
Another advantage is the fact it’s not a tower system, which normally requires jettison shortly after first stage flight. Any failure of this key sequence of ascent would end the mission, given the flight profile wouldn’t be designed for carrying the LAS along for the ride.
Because the system is integrated into the Dragon itself – as opposed to departing the spacecraft during jettison – the spacecraft can technically abort within much longer periods than the tower version. With Dragon returning with the engines on board, they can also be reused on future launches.
There is also a large amount of commonality between the 18 maneuvering engines built into Dragon and the SuperDraco LAS engines – bar the fact the SuperDraco engines would burn through propellant 200 times faster.
The additional applications of these thrusters, when unused during a nominal mission – is the ability for them to enable a return to a landing strip on land. This is a key goal as part of the fully reusable launch system SpaceX are working on, along with the potential use for landing on exploration missions, such as the surface of Mars.
A large amount of testing has already been conducted via the CCDev-2 portion of the Commercial Crew association with NASA, with the CCiCAP phase taking this literally to new heights.
First up will be the Pad Abort Test Review in March of this year, a key review ahead of a detailed plan – expected in the summer. The actual pad abort test itself will take place in December, resulting in a full-up Falcon 9 and Dragon being integrated on the Cape Canaveral launch site, prior to aborting the Dragon from the pad for a full test.
During the year, reviews will take place into the second abort test, which will result in a Falcon 9 with Dragon launching as per usual, prior to aborting at the “worst possible time” during ascent. That “In Flight Abort Test” is expected in April of 2014.
Large amounts of work will continue with upgrading the flight systems, ranging from displays to the crew to the implementation of the Merlin 1D on the upgraded Falcon 9.
However, SpaceX do not lack the drive to push foward with their human space flight ambitions, not least because their founder, Elon Musk, wants to be on a SpaceX flight to Mars while he’s still young enough.
(Images: via L2’s SpaceX Dragon Mission Special Sections – Containing presentations, videos, images (Over 2,500MB in size), space industry member discussion and more. Now includes CRS-1 Image Dump, every single hi res photo taken from the ISS – 350 Hi Res images – of which produced the lead image for this article).
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