CEV abort system gains a brain

by Chris Bergin

NASA has approached Texas Tech University to develop the software that may ultimately be used to save the lives of astronauts – during the ascent stage onboard the CEV (Crew Exploration System).

The scientists at Texas Tech are developing the Onboard Abort Executive (OAE), a software capable of making the immediate and crucial decision to decide the safest course of action during an ascent failure.

The CEV – and initially the CLV (Crew Launch Vehicle) – is currently set to debut between 2012 and 2014, replacing the Space Shuttle ahead of NASA’s next stage of the Vision for Space Exploration – with a return to the Moon and a manned mission to Mars the new goals of NASA’s return exploration outside of Low Earth Orbit (LEO).

The new vehicle will address one of the biggest criticisms of the Shuttle, a Crew Abort System, capable of saving the crew during one of the most dangerous stages of a mission – the launch and ascent.

A lengthy pole/pylon structure will be seen rising out of the top of the CEV, embedded with rockets capable of pulling the crew module clear of the first and second stages of the rocket, should a critical and dangerous failure occur during ascent, or even on the launch pad.

While the system wouldn’t of saved the crew of Columbia during STS-107, it may have saved the seven astronauts that perished on board Challenger in 1986, as their mission (STS-51L) failed during ascent due to a series of events surrounding an O-Ring failure on the right Solid Rocket Booster (SRB).

While the crew would have had no time to react to the disaster that was to occur, Challengers computers were already reacting to crippling problems in advance. However, while the Orbiter had no means of saving her crew, the CEV’s computers will have that option.

From January, NASA’s guidance, navigation and control engineers will work with Texas Tech scientists as they develop the software that will ‘monitor the crew exploration vehicle for problems, predict its abort capability and determine an appropriate strategy for doing so.’

‘The prototype will use a declarative language called SequenceL developed at Texas Tech,’ a Texas Tech release noted. ‘The language, created by Texas Tech computer science department chair Dr. Daniel Cooke, will be used to test the abort executive’s behaviour before NASA commits to building costly onboard software. This should result in fewer errors and reduce overall development costs.’

The CEV is based on a similar design as the vehicle that last transported astronauts to the Moon in the late 1960s and early 70s, earning the tag as ‘Apollo on steroids’ from NASA administrator Mike Griffin. Some of those steroids will come in the form of its state of the art computer technology being the centrepiece of the vehicle’s brain.

NASA want to see if the OAE proves to be a preferential option, with the possibility of applying its SequenceL language to other systems on the CEV – thus saving time building the brain of the vehicle.

‘Creating software prototypes and system requirements that would be easier to develop and understand while requiring less coding would allow the engineers to build and deploy new systems more rapidly – something that could be necessary as unexpected situations arise during lunar or Mars exploration missions,’ added the release.

‘The new project will determine whether SequenceL should be used to develop requirements and create software prototypes for the new Crew Exploration Vehicle.’

This collaborative project will be led by Howard Hu, Johnson Space Center’s Aeroscience and Flight Mechanics Division chief engineer for Crew Exploration Vehicle Guidance, Navigation and Control. It will also involve Cooke, faculty member Dr. J. Nelson Rushton and Texas Tech – Abilene doctoral candidate Robert Watson, who will relocate to Houston for six months.

Texas Tech are also working on NASA’s current vehicles, the Shuttle Orbiters – which will be in action for up to 19 more missions before retirement in 2010 – developing the A-Prolog language.

Created by Texas Tech computer science professor Dr. Michael Gelfond in collaboration with KSC and Houston-based space operations company United Space Alliance, A-Prolog will quickly find solutions in response to multiple failures of the Orbiter’s Reaction Control System (RCS), which are a series of thrusters that ‘steer’ the Orbiter in space. It can also be used in a similar fashion for other types of onboard systems.

‘A Concrete State Machine Language, developed by Rushton, is a language to tie A-Prolog and SequenceL into existing onboard systems,’ said Daniel Cooke, chairman, Department of Computer Science, Texas Tech University. ‘If this succeeds, it will result in a more general, integrated and formal approach to the implementation of different types of systems, including guidance, navigation and life support.’

Specific forum thread:

CEV section:

Related Articles