SpaceX: Congressional testimony

[Dr Mordrid]

Elon Musk and others testified before Congress today re: Commercial Crew Development.

Prepared comments....(PDF)

His comments varied from the prepared ones in one major area: while the NASA milestones call for an official test of the Launch Abort System SuperDraco thrusters in Q2 of next year, SpaceX plans on testing them several months ahead of schedule - Q4 of this year.

Selected bits from the prepared statement -

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The Dragon LAS is a vehicle-integrated, side-mounted engine system selected for its safety, reliability and performance after a system-level analysis conducted by SpaceX. Eight abort engines (known as SuperDracos because they are modified versions of Dragon’s existing Draco thrusters) are located around the periphery of the Dragon service section and fed by hypergolic propellant stored in the spacecraft propellant tanks.

The LAS will be enabled after crew ingress and securing on the pad and will be disabled on orbit after Dragon separation from the second stage. The launch vehicle malfunction detection system for automatic abort will monitor the Falcon 9 and Dragon for engine failures, flight control failure, failure of the booster propellant tank and failure of the booster’s primary structure, among other signatures.

Abort responses will be determined by failure(s) detected and the phase of flight, in order to maximize survivability. For example, a significantly off-nominal change in tank pressure while the vehicle is on the pad may result in an instantaneous high-acceleration abort, while a performance-related failure of the second-stage engine during ascent may result in a delayed abort until ideal entry conditions are met, a pre-abort shutdown of the second-stage engine and a low-acceleration abort profile.
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SpaceX is designing the Dragon to carry seven crewmembers seated in two rows. The seats will be conformal and a mechanical force accommodation system will cushion any off-nominal landing impacts to assure crew safety. The crew will wear spacesuits to protect them from any rapid cabin depressurization emergency event. The suits will be rated for operation at vacuum and provide communication and cooling systems.

The Dragon environmental control and life support systems will provide the crew with fresh air ventilation, remove carbon dioxide and control humidity and cabin pressure. Fire detection and suppression systems will protect the crew in the event of an emergency. Accommodations will be provided for food preparation and waste disposal.

During the span of the CCDev2 SAA, SpaceX is completing preliminary designs on modifications to our launch pad and mission control center to be ready to fly astronauts. The launch pad will have a new tower and access arm to allow crew to enter the Dragon and egress quickly in the event of a launch pad emergency. Mission control will have a new console position for a flight surgeon for human missions.

In addition to these crew vehicle systems, the operation of the vehicle for nominal, contingency and emergency situations is being outlined for all phases of flight. A crew cabin mock-up is being constructed to allow NASA astronauts to evaluate crew accommodations and other human factors considerations. We are conducting preliminary designs for crew display and manual control hardware. The detailed operation of the launch abort system is also being characterized by defining abort modes, triggering events and abort trajectories. Finally, the safety and mission assurance analyses are being evaluated with the goal of ensuring that the Dragon and Falcon 9 vehicle will achieve a level of safety better than any human spacecraft ever flown.
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SpaceX Falcon 9 / Dragon vs. Russian Soyuz

The Russian Soyuz is an unquestionably capable vehicle with significant flight heritage. Indeed, SpaceX has benefited from lessons learned from Soyuz operations and predecessor spacecraft. That said, we do not intend to duplicate the capabilities of Soyuz, but to improve upon them. Critically, the Dragon will have the capability to transport up to seven crew members to the ISS – four more astronauts than Soyuz. Further, the Dragon has the capability to carry additional unpressurized cargo to the ISS as well as the capability to return cargo from the ISS – areas in which the Soyuz is highly limited.

Additionally, the Dragon and Falcon 9 offer several safety improvements relative to the Soyuz, including:

• modern electronic control systems and computers;
• improved redundancy in the automatic control system;
• simpler and safer egress from the vehicle during an emergency on the launch pad;
• improved data displays for ascent and entry;
• capability for the crew to initiate an abort during the launch phase of the mission;
• capability for the crew to initiate the deploy of the landing parachutes;
• first stage engine out capability; and
• NASA insight into design, testing and production (NASA has limited insight to the Soyuz rocket design as well as limited access to the production facilities for the spacecraft and the rocket).

One of the largest safety distinctions between the Falcon 9 and Dragon system over the Soyuz transport system is the reduction in separation events – failure of separation events is one of the most common events leading to mission failures of space systems. The Soyuz launcher and spacecraft must release four side-mounted booster modules, the second stage, the third stage, the launch escape tower, fairing, propulsion module and habitation module prior to the point where the crew can enter safely in the Soyuz descent module. For the Dragon and Falcon 9, there are only four separation events which must occur prior to the Dragon’s entry: separation of the first stage, second stage, external cargo module or trunk and for a nominal mission separation of the nose fairing.
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