Max Launch Abort System

Fabrication and launch of the Max Launch Abort System test vehicle - July 8, 2009.

Components of the MLAS test vehicle

Concept of test vehicle operations

The Max Launch Abort System (MLAS) is a proposed alternative to the Max Faget-invented "tractor" Launch Escape System (LES) currently planned for use by NASA for its Orion spacecraft in the event an Ares I malfunction during launch requires an immediate abort.

A "pad abort" flight test of the MLAS was performed at NASA's Wallops Flight Facility on July 8, 2009 just after 6:25 a.m.^[1] A primary test goal was the successful separation of a mock crew capsule from the abort system.

Designed by NASA engineers and reported on the website nasaspaceflight.com on December 6, 2007, the proposed MLAS uses 4 existing Thiokol-Huntsville built solid-rocket motors (built in 1988) placed at 90° intervals within the Orion's bullet-shaped boost protective cover. The boost protective cover was originally designed to protect the Orion spacecraft from aerodynamic stresses during launch, and to provide an interface between the spacecraft's crew module with the LES.

The MLAS is designed with the aim of reducing the height of the Orion/Ares I stack while also reducing weight and center-of-gravity issues of a traditional LES. The bullet-shaped MLAS is also expected to provide better aerodynamic qualities during the first two minutes of flight, reducing stresses when the vehicle encounters the "Max Q" regions of hypersonic flight. The MLAS is also expected to simplify production, as existing hardware would be employed.

There are several drawbacks to MLAS. First, the bullet-shaped protective cover would have to be modified and reinforced to allow for the use of the solid-rocket motors, something not needed with the LES, which bolts atop of the LIDS docking ring assembly. Second, the necessity to fire multiple motors (LES uses one motor and multiple nozzles) simultaneously for an abort decreases the theoretical reliability of the launch abort system by introducing more failure modes.

Like the existing LES, the MLAS would provide protection to the Orion spacecraft crew during the first 2½ minutes of flight, with the MLAS being jettisoned, along with the service module's fairing panels, after the solid-rocket first stage is jettisoned. If implemented, the Orion/Ares I stack would resemble the towerless Gemini-Titan stack used between 1965–66, in which ejection seats were used as the primary form of escape for the astronauts who flew on the ten Gemini missions.

The MLAS concept was dropped with the transformation of the CEV into the MPCV, and the switch of the launch vehicle from Ares I (with its perennial underperformance) to Delta IV-Heavy or SLS.

July 2009 test launch

A Max Launch Abort System test vehicle was launched July 8, 2009, at 6:26 a.m. EDT.^[1][2] The test vehicle weighed over 45,000 pounds (20,000 kg) and was over 33 feet (10 m) tall.^[3]

The test vehicle was different from the actual system in many ways. The main difference is that the four propulsion rockets were not located in the forward fairing, but in a boost skirt located at the bottom of the test vehicle. The rockets in the fairing were represented by geometric dummies. The propulsion thrust was not balanced between the rockets by a manifold system, contrary to what is foreseen with the actual system.

See also

• Boilerplate

Media related to Max Launch Abort System at Wikimedia Commons

References

• NASA Spaceflight (main page)
• NASA Spaceflight: MLAS - the alternative Orion Launch Abort System gains momentum (full article)
• NASA page on MLAS and the Wallops pad abort test
• NASA news release on pad abort test rescheduling
• Detailed article on Wallops pad abort test on SpaceRef.com; accessed 19 June 2009
• Article on pad abort test date delay to July 2009; accessed 24 June 2009
• NASA announcement of successful pad abort test with launch photo; accessed 8 July 2009

1. ^ ^{a b} NASA Tests Alternate Launch Abort System for Astronaut Escape
2. ^ "MLAS Image Gallery (Image 1)". NASA ESMD. July 8, 2009. http://www.nasa.gov/exploration/multimedia/galleries/mlas-13.html. 
3. ^ "MLAS". NASA Wallops. http://www.nasa.gov/centers/wallops/missions/mlas.html. Retrieved July 11, 2009.