Listen To The Martian Wind / China’s Daring Mission To The Lunar Farside

Listen to the sound of Martian winds from NASA’s InSight lander. The fluttering sound is very familiar.

NASA’s InSight lander which touched down on Mars almost two weeks ago has provided the first ever “sounds” of Martian winds on the Red Planet. The lander’s sensors captured the low rumble caused by vibrations from the wind, estimated to be blowing between 10 and 15 mph (15-25 kph) on Dec. 1. The direction of the winds, out of the northwest, was consistent with the direction of streaks left by dust devils in the area observed from orbit.

This image from InSight shows the instruments on the spacecraft’s deck.Taken on Dec. 4, it shows the copper-colored cover protecting the seismometer that will measure marsquakes. The gray dome behind SEIS is the wind and thermal shield, which will be placed over the instrument. The black cylindrical instrument (left) is the Heat Flow and Physical Properties Probe (HP3). HP3 will drill up to 16 feet (5 meters) below the Martian surface, measuring heat released from the interior of the planet. NASA/JPL-Caltech

No one planned to capture the sounds but it so happened that two sensors on the spacecraft — an air pressure sensor inside the lander and a seismometer that’s sitting on the lander’s deck before it’s placed on the surface — were sensitive enough to record the wind noise. The air pressure sensor picked it directly as changes in pressure as wind blew past, while the seismometer recorded lander vibrations as wind moved over the spacecraft’s solar panels. Each is 7 feet (2.2 meters) in diameter and sticks out on either side of the lander, providing a large surface area for the wind to affect.

In a few weeks, mission control will use InSight’s robotic arm to place the seismometer on the surface and then cover it with a domed shield to protect it from wind and temperature changes. It will still detect the lander’s shimmy from wind but through the surface. Ironically, the wind vibrations it’s recording now will be used to cancel out the noise the lander will produce, making it easier to detect actual marsquakes.

This artist concept shows InSight with its instrumenst set up and running including the heat probe (HP3) at left and the seismometer (SEIS) at right. NASA/JPL-Caltech

When earthquakes occur on Earth, the vibrations they create bounce around inside our planet similar to the vibrations produced in a bell when the clapper strikes the metal. The vibrations reveal much about the Earth’s internal structure, and scientists with the InSight mission hope they’ll be able to probe Mars’ interior in a similar way using Mars-tremors.

You might be wondering how a planet that doesn’t have shifting crustal plates, the cause of earthquakes here on Earth, could tremble. But you don’t need a giant quake to make a planet tremble. InSight should be able to sense tremors caused by meteorite impacts, magma moving deep beneath the Martian surface and cracking rock from contraction caused by cooling.

The seismometer readings are in the range of human hearing, but are nearly all bass and difficult to hear on laptop speakers and mobile devices. The video (above) has the original audio and a version pitched up by two octaves to make them audible on mobile devices. To hear the original, raw version, a subwoofer and headphones are recommended. Readings from the air pressure sensor have been sped up by a factor of 100 times to make them audible.

We’ll be hearing much more from Mars when the Mars 2020 lander touches down on the planet in February 2021. It will have two microphones on board, one of them to record the sound of a Mars landing along with the wind and rover at work, and a second to support the SuperCam. SuperCam will examine rocks with a camera, laser and mineral-fingerprinting spectrometer looking for organic compounds. The microphone will be able to detect the sound of the instrument’s laser as it zaps different materials; changes of pitch will help identify the materials getting zapped.

Chang’e 4 lunar probe

In other space news, China launched a daring mission to the far side of the moon on Friday. Named Chang’e 4 for the Chinese moon goddess, it would be the first soft landing on the lunar farside and include a rover to study the surface rocks, listen for moonquakes and gather information on the solar wind and its affects on the moon’s soil and rocks.

The top photo in this panel shows the Chang’e 3 lander and rover taken during China’s last mission to the moon in 2013. The bottom photo of the lander, rover and surroundings was taken by NASA’s Lunar Reconnaissance Orbiter. The new rover-lander is of similar design but with improvements. CNSA (top) and NASA

Because the moon’s rotation nearly matches its revolution, it essentially keeps one face turned toward Earth and the other — the far side — turned perpetually away. No radio communications can penetrate the moon’s rocky body to reach a probe placed on the farside, so earlier this summer China launched a relay satellite 37,300 miles (60,000 km) beyond the Moon into a stable orbital “parking spot” called the L2 Langrange point. From this vantage, it can provide communications from the lander to the Earth and back.

The far side of the moon is extremely rugged compared to the near side. Von Kármán crater is boxed (left) and shown in close-up (right) with the likely landing area within the yellow oval. NASA

The scary part is that the landing will take place completely out of sight according to preprogrammed instructions. The Chinese space program is vague on details, but the landing is expected during the first week of January 2019, when Chang’e 4 will touch down in one of the few relatively smooth and safe areas on the farside, the 112-mile-wide (180 km) Von Kármán crater located in the South Pole-Aitken Basin, the largest, deepest impact basin on the moon. Scientists are hoping to study some of the most ancient rocks exposed here from the deep mantle of the moon.

The lander and rover are equipped with solar panels to generate electricity and plutonium-238 heaters to keep their instruments warm during the lengthy lunar night. More missions are planned including Chang’e 5, expected to launch sometime next year and return rock and soil samples to Earth.

2 Responses

  1. Edward M. Boll

    It has been completely over cast here for the last 2 weeks. It just cleared enough to find Mars the other night and a blue type star, probably Neptune but I have yet to confirm that with my charts. My binoculars are big. This morning despite clouds and fog, I could barely make out Venus.

    1. astrobob

      I feel for you, Edward. I’ve been through these long spells, too. They’re the worst. I hope it clears just in time for you to catch the comet at its best.

Comments are closed.