DPA MICROPHONES ON MARS

Hear the sound of Martian wind

Until recently, no one had ever heard anything from within the Martian atmosphere. In fact, the first sounds were only heard on December 1, 2018. A highly-sensitive seismometer on board NASA's InSight Mars Lander recorded vibrations caused by Martian wind. In addition, the vehicle's air pressure sensor also recorded the sound of wind. The sounds were picked up by instruments made for other purposes than sound thus the recordings are analogies to what you could expect to hear.

To gain some further insights into the Martian soundscape, the Mars 2020 Rover will be outfitted with audio equipment from DPA Microphones. Just imagine the range of sounds that a dedicated microphone could record during the trip – leaving outer space, entering the atmosphere and, eventually, on the planet's surface.

What DPA equipment is making the trip?

For this partnership, NASA has strenuously tested a variety of mics and chosen a selection of equipment from DPA. The 4006 Omnidirectional Microphones will be the Rover's "ears"; attached to the vehicle and paired with MMP-G Modular Active Cables, which will act as ultra-transparent preamplifiers. Inside the body of the vehicle, acting as the auditory part of the "brain", will be a MMA-A Digital Audio Interface. The MMA-A's job is to digitalize the audio in the highest quality and send it to a computer in the Rover through a USB connection.

The trip to Mars is not a simple walk in the park. It will subject the Rover to extreme temperatures (as low as -100°C/ -148°F), wildly varying travel pressure and intense vibrations. To ensure that the equipment lands on Mars in good working order, the spacecraft design team has created a specialized enclosure to mount the MMA-A interface inside the rover chassis. In addition, NASA's Jet Propulsion Laboratory (JPL) and the DPA R&D team worked together to create a custom MMP-G amplifier housing to bolt onto the exterior of the Rover.

Besides the customized amplifier housing, no major changes were made to the equipment once it left the DPA factory. The mic you know and love, the one that captures your favorite orchestra arrangement or records ambient sound for your favorite TV series is the same as the one that will take the long trip to Mars.

What will the mics be used for?

One of the riskiest parts of the mission, entry, descent and landing (EDL) tracks the Mars 2020 Rover from the time it enters the atmosphere until touchdown in the Martian dust. No one has ever seen or heard a parachute opening in the Martian atmosphere, the rover being lowered down to the surface of Mars on a tether from its descent stage, the bridle between the two being cut or the descent stage flying away after the Rover lands!

The DPA microphones' mission is to capture these sounds for NASA. Not only will this allow project engineers and scientists to hear the fascinating sounds of the Rover descending, but the curious public will be able to follow along as well.

Update 18/3/2021

After over two weeks of dramatic temperature changes and dusty winds on the surface of Mars, the DPA solution, consisting of a 4006 Omni Mic, MMA-A Digital Audio Interface and MMP-G Modular Active Cable, is still going strong. 

The Perseverance rover is currently rolling around the bumpy terrain of Mars and it isn't a quiet drive through the country. Bangs, pings and rattles from the rover's six wheels are clearly audible in the tracks released by NASA. The wheels are made of metal and the vehicle is driving over rocks, which is why it is so noisy. 

"If I heard these sounds driving my car, I’d pull over and call for a tow. But if you take a minute to consider what you’re hearing and where it was recorded, it makes perfect sense.”

–  Dave Gruel, lead engineer for Mars 2020’s EDL Camera and Mic subsystem

Update 22/2/2021

NASA’s Mars 2020 Rover took off on July 30, 2020, for a seven-month journey to the mysterious Red Planet. It touched down successfully on February 18, 2021 with a DPA 4006 Omnidirectional, an MMA-A Digital Audio Interface and an MMP-G Modular Active Cable in tow.

"Everything about the mission — from the launch to the landing — is hostile, insofar as a microphone is generally concerned. It’s very exciting to know that DPA was able to record something from so many millions of miles away, and have the sound travel back to us so quickly."  

–  René Mørch, product manager at DPA Microphones

After the rover touched down, audio and video files were recorded from the surface and transmitted to NASA’s base station. NASA sent these files to DPA’s engineering team for processing and review. Now you can hear the first sound ever captured on Mars with a microphone. 

DPA and Apollo 13

The first collaboration took place close to 50 years ago. Apollo 13 was sent into space in April 1970 and B&K measurement mics (the predecessor of current DPA microphones) were used to record the sound of liftoff. The capsule used was called the B&K 4133, which is the father of DPA's 4004/4007.

Mission STS-63

Mission STS-63 to launch Space Shuttle Discovery into space (with the first female shuttle pilot) in February 1995 was also recorded with DPA microphones. These mics were the same type as used during the Apollo 13 mission.

Recording Shuttle launches present some extraordinary technical difficulties, not least because sound pressure levels can reach 170 dB. In addition, the microphones used must be able to survive the blast, which is an extremely violent affair. At the moment of lift off, there is intense heat and flames as well as chemicals sprayed all over the launch pad.

One mic was set just 500 feet away from the launch pad, where it handled 170 dB without distortion. Another was set 1400 feet away and subjected to 146 dB. A mile away, a third mic recorded 125 dB of SPL. The sounds recorded from these mics were subsequently used by a number of broadcast networks, including ABC, NBC and CNN.