Max Launch Abort System

{{Short description|Proposed pusher alternative to the Orion escape rockets}}

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File:Fabrication and launch of the Max Launch Abort System - July 8 - 2009.ogg

File:MLAS components.jpg

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The Max Launch Abort System (MLAS) was a proposed alternative to the Maxime Faget-invented "tractor" launch escape system (LES) that was planned for use by NASA for its Orion spacecraft in the event an Ares I malfunction during launch required an immediate abort.{{cite web|url=https://www.nasa.gov/exploration/features/MLAS_overview.html|title=NASA's Max Launch Abort System (MLAS) Overview|publisher=NASA|access-date=August 15, 2024}}

Designed by NASA engineers and reported on the website NASASpaceFlight.com on December 6, 2007, the proposed MLAS used four existing Huntsville-built Thiokol solid-rocket motors (built in 1988) placed at 90° intervals within the Orion's bullet-shaped fairing.{{cite news|url=https://www.nasaspaceflight.com/2007/12/nasa-considering-alternate-launch-abort-system-for-orion/|title=NASA Considering Alternate Launch Abort System for Orion|work=NASASpaceFlight.com|date=December 6, 2007|access-date=August 15, 2024}} The fairing 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 was 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.{{cite web|url=https://www.nasa.gov/mission_pages/constellation/main/index.html|title=NASA's Constellation Program: Max Launch Abort System|publisher=NASA|access-date=August 15, 2024}} The bullet-shaped MLAS was also expected to provide better aerodynamic qualities during the first two minutes of flight, reducing stresses when the vehicle encounters the "max Q" region of hypersonic flight.{{cite web|url=https://www.nasa.gov/feature/max-q-the-ultimate-challenge-of-space-flight|title=Max Q: The Ultimate Challenge of Space Flight|publisher=NASA|date=October 29, 2019|access-date=August 15, 2024}} The MLAS was also expected to simplify production, as existing hardware would be employed.{{cite web|url=https://www.nasa.gov/centers/wallops/news/feature10.html|title=NASA's Wallops Flight Facility and the MLAS|publisher=NASA/Wallops Flight Facility|date=July 1, 2009|access-date=August 15, 2024}}

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 on top of the LIDS docking ring assembly.{{cite book|last=Isakowitz|first=Steven J.|title=International Reference Guide to Space Launch Systems|publisher=AIAA|year=2010|isbn=978-1-60086-784-2|pages=357–359}} 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.{{cite journal|last1=Wood|first1=Eric M.|title=Reliability Considerations of Multiple Solid Rocket Motors in Launch Abort Systems|journal=Journal of Spacecraft and Rockets|volume=47|issue=2|year=2010|pages=317–321|doi=10.2514/1.47414|doi-broken-date=1 November 2024 }}

Like the existing LES, the MLAS would provide protection to the Orion spacecraft crew during the first {{frac|2|1|2}} minutes of flight, with the MLAS being jettisoned, along with the service module's fairing panels, after the solid-rocket first stage was jettisoned.{{cite book|last=Connors|first=Mary M.|title=Launch Escape Systems and Emergency Recovery: Historical Overview and Future Prospects|publisher=NASA|year=2008 |pages=112–115}} If implemented, the Orion/Ares I stack would have resembled the towerless Gemini-Titan stack used between 1965 and 1966, in which ejection seats were used as the primary form of escape for the astronauts who flew on the ten Gemini missions.{{cite book|last=Shayler|first=David|title=Gemini: Steps to the Moon|publisher=Springer-Praxis|year=2001|isbn=978-1-85233-405-5|pages=192–194}}

The MLAS concept was dropped with the transformation of the Crew Exploration Vehicle into the Orion Multi-Purpose Crew Vehicle, and the switch of the launch vehicle from Ares I (with its perennial underperformance) to the Delta IV Heavy or Space Launch System.{{cite web|url=https://www.nasa.gov/exploration/systems/mpcv/index.html|title=NASA's Orion Multi-Purpose Crew Vehicle (MPCV)|work=NASA |date=15 January 2015 |access-date=August 15, 2024 |last1=Garcia |first1=Mark }}