Wednesday, September 2, 2015

Orion Spacecraft Arrives in Colorado for Post-Flight Testing

Orion spacecraft arrives in Colorado for post-flight testing. Credit: Lockheed Martin

NASA’s Orion spacecraft that flew 3,600 miles into space during the Exploration Flight Test-1 in December 2014, has been shipped to the Lockheed Martin Space Systems Company headquarters in Littleton, Colorado for final decontamination and testing. The crew module will undergo post-flight analysis of selected components, and will evaluate a new acoustic technology called Direct Field Acoustic (DFA) testing.

DFA is a technique used for acoustic testing of aerospace structures by subjecting them to sound waves created by an array of acoustic drivers. The evaluation of DFA testing will determine if the method can produce enough energy to simulate the acoustic loads Orion will experience during launch and ascent on the Space Launch System (SLS) rocket.

During the test, customized, high-energy speakers, configured in a circle around the Orion spacecraft, will use a specific algorithm to control how much energy reaches the vehicle. Lockheed Martin, which built the capsule, revealed that the amount of speakers needed for the test will fill up three tractor-trailers. The tests will conclude in early 2016.

DFA method could be used in the future to evaluate and verify Orion’s ability to withstand acoustic loads during its next flight, Exploration Mission-1 (EM-1) in November 2018. The vehicle will be also reused around 2017 for a launch abort test. When fully developed, Orion will be capable of sending humans to deep space destinations such asteroids and Mars.

The DFA system employs arrays of narrow-dispersion enclosures loaded with high-capability drivers combined with extremely high output stereo amplifiers. This method can be used to produce an acoustic environment that can simulate helicopter, aircraft, jet engine or launch vehicle sound pressure fields. The system is capable of producing 130dB to 147dB Overall Sound Pressure Levels for more than one minute over a frequency range from 25 Hz to 10 kHz.

DFA has been used for production testing for over 12 years with more than 85 tests successfully completed. For example, it was performed on NASA’s QuikSCAT spacecraft in October 1998. The spacecraft was surrounded with a three-meter-high ring of large, electrodynamic speakers, spaced approximately 1.3 meters (4.26 ft.) away from the two-meter-diameter, 2,000 lbs. spacecraft. The thirty-one speaker cabinets were driven with 40,000 rms watts of audio amplifier power. The acoustic specification, with an overall sound pressure level of 135 dB, was achieved one meter in front of the speakers.

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