A risky mission...STS-125 was the long-awaited final repair mission to the Hubble Space Telescope. Flown by space shuttle Atlantis, STS-125 was launched as an extremely risky mission: not only would the crew not have safe haven on the International Space Station in the case of an emergency with the shuttle's critical systems or thermal protection system, the higher orbit of Hubble ran the risk of damage by space debris.
To rescue the crew in case of an emergency, space shuttle Endeavour sat nearby at launch pad 39B, ready to launch in a matter of days if a problem were to come up.
This mission was also historic in that it's the last mission flown by a space shuttle that doesn't involve space station construction; it's also one of the last flights of Atlantis before the space shuttle program is finished.
This mission was also documented by IMAX with their IMAX-3D system, for an upcoming IMAX release in 2010.
Wind & TemperatureThis launch recording was specially challenging; there were some rather strong winds, which always is disappointing for recording a launch. Since the sound has quite a distance to travel -- a little over three miles -- there's a lot of room for the soundwaves, however strong, to be re-routed due to wind.
Interested in learning more about how sound travels? Here's a very easy explanation.
Also, the launch was scheduled at mid-day, at the highest temperature point of the 24-hour period. This means the sound would travel slightly slower, and possibly have less impact.
One plus was the planned trajectory: Atlantis would roll into a heads-down position and fly directly east from launch pad 39A; previous missions to the ISS launched in a north-northeast direction. This put a majority of the shockwave directly towards the complex 39 press site.
The Right Gear...For this launch, our friends at Earthworks Precision Audio lent a pair of their flagship microphones -- the QTC50. These omnidirectional microphones have a linear-flat response of 9hz to 50kHz, an extremely high-definition range of sound. They're also extremely sensitive while retaining very high SPL handling capabilities.
Following the microphones in the signal chain, I called to action my favorite portable preamplifier, the Grace Design V2. This is my favorite preamp for a variety of reasons; it's operable on a simple 6 volt battery, is super clean, very quiet, and very lightweight. In fact, the whole rig -- battery, preamp, cables, and recorder -- fits into a standard camera bag!
For this recording, I used an evaluation unit of the M-Audio Microtrack II, operating at 24-bit, 96kHz.
The microphones were split 3 feet, pointed due east to capture the shockwave from the liftoff. With omnidirectional microphones, setting them up 3-5 feet apart will help give a large, spatially-balanced stereo image to your recording.
It's showtime...Atlantis launched on time at 2:01 PM EDT on May 11, 2009.
Upon liftoff, the sound was just as I expected: slightly more delayed than usual, due to the temperature (a timestamp shows the sound reached us about 17 seconds after liftoff), and, very surprisingly, quite powerful. The due-east trajectory definitely helped, and many commented at the press site that it was one of the more powerful launches they've felt during the day.
I highly recommend listening to this recording on a system with very good bass response; you'll hear just how powerful the rumble of the solid rocker boosters was this time around!
If you listen closely, you'll also notice that the angle of launch caused a lot of vibrations to bounce off the large Vehicle Assembly Building, giving a sense of first and second reflections by the time it reached us.
Atlantis returned safely to Earth on May 24th after several landing delays due to weather. All elements of the Hubble repair mission were deemed successful.
I continue to get wonderful feedback from readers who love hearing these recordings. Look for new recordings following the upcoming final launches of the space shuttle program, so we can re-live history together, in high-definition audio!