Identification of Acoustic Sources on Antares Launch Pad Using Microphone Phased Array

Abstract

A microphone phased array (MPA) was mounted in the vicinity of pad 0A of Mid-Atlantic Regional Spaceport located on NASA’s Wallops Flight Facility to identify the evolution of acoustic sources from hold-down to an elevation of [Formula: see text] during the launch of an Antares rocket (Northrop Grumman [NG]-19). The MPA was equipped with 70 piezo-resistive dynamic pressure sensors, a visible-band and an infrared-band camera, and a two-axis accelerometer. The noise map demonstrated an effective use of the water injection system to attenuate noise from plume impingement on the pad. They also pointed out the outlet of the exhaust duct, through which the steam and plume mixture ejected out, to be the primary noise source during a significant interval of time. A comparison with prior such measurements during the maiden launch of the Antares vehicle in 2013 showed significant attenuation of noise sources during the NG-19 launch. A strong source caused by the impingement of plume on the pad surface during the 2013 launch was found to be attenuated in 2023. The results showed the utility of an MPA in quantifying the impact of changes made to a launch pad.