Listening to Winds On Alien Worlds Is More Complicated Than it Sounds

InSight’s recording of Martian winds isn’t what you’d hear if you were on the planet yourself

Artist’s impression of the European Huygens lander that descended through Titan’s atmosphere and landed on the Saturn moon’s surface [ESA]

We live in a world where spacecraft are now routinely landing on other worlds and recording their sounds. Soviet probes aimed at Venus captured the thunder and howling winds on the volcanic world, giving us the first ever audio recording captured beyond Earth. We’ve been able to reconstruct the sound of alien rain on Saturn’s moon Titan. And now, for the first time, we get to hear the low hum of Martian winds sweeping down the planes. Except not exactly. You see, while InSight did in fact record a 10 to 15 mile per hour draft on Martian, the recording’s pitch had to be dialed up and its frequency sped up roughly 100 times for the human ear to make any real sense of it. But why is it so hard to hear them otherwise?

Unlike Venus or Titan, Mars has an extremely thin, barely there atmosphere stripped away by solar winds and with virtually no protection from its weak magnetosphere. It’s so thin and fragile that it might actually make the planet impossible to terraform if we ever wanted to try to make it even a little more like our world. Even hurricane force winds would feel like a gentle breeze because there’s just not enough air to impart any meaningful kinetic energy. So, if you were able to stand on the surface of Mars without a spacesuit, you’d probably hear and feel nothing, hence NASA had to help us out so we could get some appreciation of what they were able to record, which is still exquisitely haunting and beautiful in the end.

What about winds on other planets and moons?

With extremely thick atmospheres, you’d have absolutely no problem hearing and feeling the full force of the wind on worlds like Venus, Jupiter and the other gas giants, and of course, Titan. In the turbulent clouds of gas giants, the winds would never stop and without anything solid to act as a brake, gusts can howl at astonishing speeds. Neptune boasts the fastest winds in the solar system at 1,200 miles per hour, with Saturn not far behind as 1,118 mile per hour gales whip around its equator, making Jupiter seem almost inert by comparison with peak wind speeds of 384 miles per hour around its Great Red Spot.

Exactly how hard that wind would hit you will depend on your altitude in the gas giants’ vast atmospheres but analogies with the impacts of anything between a tornado and a freight train come to mind. At this point, we would consider the kinetic energy of winds on Venus and Titan because they have solid surfaces and very thick atmospheres, but on both worlds, a very odd and interesting thing happens as you descend through the clouds. That atmospheric thickness means that gasses are compressed as you get close and closer to the surface and winds very quickly die down under the mass of the air through which they have to move.

On Titan, winds reach maybe 2 miles per hour at ground level at their strongest. On Venus, they peak at 3 miles per hour. Still, because there’s so much mass in motion, they would feel like a stiff breeze of 20 to 25 miles per hour if we note that the gusts in question are strong enough to scatter small rocks and use the Beaufort scale to translate that into comparable conditions right here on Earth. You would certainly hear it as well, deeper and more ominous than you’d expect, with absolutely no need to increase the pitch or speed up frequency for your ear to know what’s happening.

So, in case you ever look at the night sky and wonder about how different other planets are from the one on which you’re standing, consider that something seemingly as simple as the sound of moving air can be vastly different from world to world, what you’d consider a gentle breeze could be imperceptible on one planet and blow an umbrella out of your hand on another, and that sometimes, to appreciate what our robotic probes are detecting, we need to specially process the data they’ve gathered so you can even start making sense of it.

[This article originally appeared on World of Weird Things]

InSight Mars Lander Gets Used to Its New Digs, Snaps a Selfie

The NASA mission looks like it’s getting comfortable in Elysium Planitia.

The view from InSight’s Instrument Deployment Camera (IDC), which is attached to the lander’s robotic arm, looking over the flat and rock-strewn plane of Elysium Planetia, on sol 14 of its mission. The lens flare is caused by the Sun that is just out of shot [NASA/JPL-Caltech]

Like any self-respecting social media influencer, Mars’s latest resident is hard at work snapping photos of its new digs. The robot has even thrown in a beautiful selfie for good measure.

NASA’s InSight lander touched down on the Red Planet on Nov. 26 and since then its mission controllers have been hard at work checking out the instrumentation and surroundings. Using its Instrument Deployment Camera, or IDC, InSight has been giving us a tour of its permanent home. Fans on social media have even been nominating names for the rocks that can be seen embedded in the dusty regolith — the only rocks we’ll see close up for the duration of the mission. 

Dusty with a dash of small rocks, perfect ground for InSight’s work [NASA/JPL-Caltech]

Very early on, NASA scientists knew they’d landed in the right place. The beautifully-flat plain of Elysium Planitia has a landscape that is in stark contrast to Curiosity’s Mount Sharp environment; instead of seeing a smorgasbord of geological features — created by ancient water action and ongoing aeolian (wind-blown) processes — Elysium is flat, dusty and appears to only have small-ish rocks strewn over its surface. You see, InSight cares little for what’s on the surface; the science it’s after lies below the stationary lander, all the way to the planet’s core.

“The near-absence of rocks, hills and holes means it’ll be extremely safe for our instruments,” said InSight’s Principal Investigator Bruce Banerdt of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., in a statement. “This might seem like a pretty plain piece of ground if it weren’t on Mars, but we’re glad to see that.”

One of InSight’s three legs can be seen here slightly sunken into the Martian regolith, showing us how soft and powdery the uppermost layers of the mission’s landing zone is. Oh, and that rock to the right? Luckily InSight missed it [NASA/JPL-Caltech]

Now that InSight’s raw image archive is churning out new pictures daily, mission scientists are scoping out its “work space” directly in front of the lander’s robotic arm. Over the coming weeks, optimal positions for InSight’s two main experiments — the Seismic Experiment for Interior Structure (SEIS) and Heat Flow and Physical Properties Package (HP3) —will be decided on and then commands will be sent to the lander to begin the painstaking task of retrieving them from its deck and setting them down on the ground. The main task will be to determine exact locations that are smooth, flat and contain small rocks that are no bigger than half an inch. This will ensure stable contact with the ground so seismic and heat flow measurements can be continuously carried out. InSight is basically going to give Mars an internal examination 24/7, listening to the slightest seismic waves like a doctor would listen to your heartbeat. And it looks like InSight has landed inside a depression, likely created by an ancient crater that has been filled with loose material over time — this is great news for HP3 that has a self-digging probe (called the “mole”) that will now have an easier task of burrowing meters underground.

But what about that selfie? Well, here you go:

InSight says hi! [NASA/JPL-Caltech]

This photo is a mosaic composed of 11 different images snapped by the lander’s robotic arm-mounted camera. You can see the lander’s open solar panels and stowed instrumentation on the deck, including SEIS and HP3. And no, the selfie isn’t a fake; by sticking a bunch of individual photos together, they’ve overlapped to edit out any trace of the arm itself. Curiosity does the same thing; so did Opportunity and Spirit. InSight’s older sibling, Phoenix also did it. Selfies are as much the rage on Mars as they are on Earth. Not only do they look cool, they are also useful for mission controllers to monitor the build-up of dust on solar panels, for example.

For now, as we await the science to start flowing in (well, there’s been some early science before the robot has even gotten started), enjoy checking back on InSight’s raw photos, it won’t be long until we’ll be browsing through potentially thousands of snaps from Elysium Planitia. Oh, and don’t forget about Curiosity that’s still going strong on the slopes of Mount Sharp!

We’re Really Confused Why Supermassive Black Holes Exist at the Dawn of the Cosmos

eso1229a
ESO

Supermassive black holes can be millions to billions of times the mass of our sun. To grow this big, you’d think these gravitational behemoths would need a lot of time to grow. But you’d be wrong.

When looking back into the dawn of our universe, astronomers can see these monsters pumping out huge quantities of radiation as they consume stellar material. Known as quasars, these objects are the centers of primordial galaxies with supermassive black holes at their hearts.

Now, using the twin W. M. Keck Observatory telescopes on Hawaii, researchers have found three quasars all with billion solar mass supermassive black holes in their cores. This is a puzzle; all three quasars have apparently been active for short periods and exist in an epoch when the universe was less than a billion years old.

Currently, astrophysical models of black hole accretion (basically models of how fast black holes consume matter — likes gas, dust, stars and anything else that might stray too close) woefully overestimate how long it takes for black holes to grow to supermassive proportions. What’s more, by studying the region surrounding these quasars, researchers at the Max Planck Institute for Astronomy (MPIA) in Germany have found that these quasars have been active for less than 100,000 years.

To put it mildly, this makes no sense.

“We don’t understand how these young quasars could have grown the supermassive black holes that power them in such a short time,” said lead author Christina Eilers, a post-doctorate student at MPIA.

Using Keck, the team could take some surprisingly precise measurements of the quasar light, thereby revealing the conditions of the environment surrounding these bright baby galaxies.

discoveryint
MPIA

Models predict that after forming, quasars began funneling huge quantities of matter into the central black holes. In the early universe, there was a lot of matter in these baby galaxies, so the matter was rapidly consumed. This created superheated accretion disks that throbbed with powerful radiation. The radiation blew away a comparatively empty region surrounding the quasar called a “proximity zone.” The larger the proximity zone, the longer the quasar had been active and therefore the size of this zone can be used to gauge the age (and therefore mass) of the black hole.

But the proximity zones measured around these quasars revealed activity spanning less than 100,000 years. This is a heartbeat in cosmic time and nowhere near enough time for a black hole pack on the supermassive pounds.

“No current theoretical models can explain the existence of these objects,” said Joseph Hennawi, who led the MPIA team. “The discovery of these young objects challenges the existing theories of black hole formation and will require new models to better understand how black holes and galaxies formed.”

The researchers now hope to track down more of these ancient quasars and measure their proximity zones in case these three objects are a fluke. But this latest twist in the nature of supermassive black holes has only added to the mystery of how they grow to be so big and how they relate to their host galaxies.

Supermassive black hole with torn-apart star (artist’s impress
A supermassive black hole consumes a star in this artist’s impression (ESO)

These questions will undoubtedly reach fever-pitch later this year when the Event Horizon Telescope (EHT) releases the first radio images of the 4 million solar mass black hole lurking at the center of our galaxy. Although it’s a relative light-weight among supermassives, direct observations of Sagittarius A* may uncover some surprises as well as confirm astrophysical models.

But as for how supermassive black holes can possibly exist at the dawn of our universe, we’re obviously missing something — a fact that is as exciting as it is confounding.