Rocket noise: What does it mean for Australian spaceports?
Kent L. Gee – kentgee@byu.edu
Twitter (x): @KentLGee
Instagram: @gee.kent
Brigham Young University, Provo, UT, 84602, United States
Logan T. Mathews, Bradley McLaughlin, Mark C. Anderson (@AerospaceMark), Grant W. Hart
Brigham Young University, Utah, USA
@BYU_PASCAL
@BYUAcoustics
Daniel Edgington-Mitchell
Monash University, Victoria, Australia
@MonashUni
Popular version of 5PNSa1 – Rocket noise: What does it mean for Australian spaceports?
Presented at the 185th ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0023749
Please keep in mind that the research described in this Lay Language Paper may not have yet been peer reviewed.
The global space industry is rapidly expanding. Rockets are being launched from a greater number of spaceports and a recent exponential increase in annual global orbital launches (Figure 1) has surpassed numbers seen during the 1960s’ Space Race. While about 75% of rockets are currently launched from the United States and the People’s Republic of China, an increasing number of countries are tapping into a global space launch services market projected to reach USD 33.4 billion in 2028. The Australian Space Agency was created in 2018 to support the growth of Australia’s space industry and the use of space across the broader economy. Australia is well-situated for launching payloads to a variety of orbits and multiple spaceports are being constructed or planned.
Figure 1. Global orbital launches by year.
Figure 1. Global orbital launches by year.The power generated by rockets during liftoff and ascent generates lots of noise, which can cause possibly damaging vibration of the payload, rocket, and launchpad structures. Farther away, the noise may have short and long-term impacts on communities and the environment, although these impacts are at present poorly understood.
Rocket noise is generated by the high-speed turbulent exhaust plume mixing with the outside air. Although less than 1% of the plume’s mechanical power is turned into sound during liftoff, even a small orbital rocket creates several times more sound power than a military jet aircraft at afterburner. The most powerful orbital rocket, NASA’s Space Launch System (SLS), generates sound power equal to nearly 900 T-7A aircraft.
Near-term, orbital rockets that will launch from Australian spaceports are relatively small. From U.S.-based Phantom Space’s Daytona rocket to Gilmour Space Technologies’ Australian-built Eris rocket, these vehicles will have a much smaller noise footprint than SLS or SpaceX’s oft-launched rocket, the Falcon 9 (see Fig. 2.) However, peak noise levels within several meters of these rockets will still exceed 180 dB and maximum sound levels tens of kilometers away will be above typical background noise, particularly at low frequencies. For example, Figure 3 is a maximum sound level map from a small rocket launched to the east over the Great Barrier Reef. Maximum launch levels along portions of the reef are predicted to be 70-75 dB, not including the ascent sonic boom, which can be significantly louder.
Figure 2. Near-term orbital launch vehicles to be launched from Australia are significantly smaller than the well-known Falcon 9.
Figure 2. Near-term orbital launch vehicles to be launched from Australia are significantly smaller than the well-known Falcon 9.
Figure 3. RUMBLE-predicted maximum sound level footprint over the Great Barrier Reef for a small orbital rocket launch from the Bowen Orbital Spaceport.
Figure 3. RUMBLE-predicted maximum sound level footprint over the Great Barrier Reef for a small orbital rocket launch from the Bowen Orbital Spaceport.Will launches from Australian soil create damaging vibrations or harmful environmental noise impacts? That is a complex question that depends on vehicle size and design, launch cadence, distance to structures, habitats, and communities, weather patterns, and other factors. Continued study of the multiple facets of generation, propagation, and reception of rocket noise will help find answers and improve our access to space, from Australia and worldwide.