The sand dunes on the surface of Mars closely resemble their terrestrial cousins, only bigger. Formed from wind-driven sand and dust, the Martian versions can grow ten-times bigger than any dunes we have on Earth. The High Resolution Imaging Science Experiment (HiRISE) on board NASA’s Mars Reconnaissance Orbiter (MRO) has been taking shots of these distinctive shapes, and although there are examples all over the planet, they seem to have the same characteristics no matter where they form or how they swarm. Now researchers are investigating how these Mars dunes grow and why they are so large…
On the 11th April, I reported on some new HiRISE images of barchan sand dunes that appeared to form on the Red Planet. In this particular case, a flat-topped mountain (or mesa) was being ravaged by the Martian wind, sweeping fine grains of sand and dust downstream. What formed in the mesa’s wake turned out to be quite impressive. Long strands of sand banks, stretching hundreds of miles beyond the mesa mixed with swarms of similarly-shaped dunes. What struck me were the impressive similarities with Earth-based sand dunes we find on our beaches and deserts.
Since this initial report, I have found HiRISE to be quite a prolific dune-seeker. On April 16th, HiRISE released more images of sand dunes in the northern polar regions of Mars, some heavily eroded (pictured below), and others tightly packed and clumsily shaped. I was intrigued. As you may have noticed from some of the Mars stories I cover, I like to see terrestrial processes happening on the surface of Mars. Seeing an impressive Mars avalanche, or a simple rock rolling down a hill, I love it. I think it gives us a special connection with an alien world when we can see processes we commonly associate with Earth happening on an eroding Mars.
So what processes are behind these giant Mars dunes? It might seem obvious (wind blowing sand ain’t that hard to understand after all), but researchers at the Federal University of Ceará in Fortaleza, Brazil have been modelling the effects that the tenuous Mars atmosphere and weak gravity have on sand dune construction. Murilo Almeida and his team have found that when blown around on the surface of Mars, grains of sand “bounce” much higher than their terrestrial counterparts. In fact, they bounce 100 times higher and further. They are also blown 10 times faster. This has the effect of producing a series of sand dunes with very long wavelengths.
This also has a knock-on effect as a possible mechanism that drives the savage dust storms in the thin atmosphere. As there is more bouncing action in Martian grains of sand than here on Earth, more dust particles are thrown aloft and suspended in the air.
Imagine that you have just set up camp on Mars. Everything is up and running. You and your team have not only survived the journey from Earth, you’ve also made it through fiery re-entry and landed within a metre of your planned location. Success! So you crack open a miniature bottle of vintage whisky bottled in the year 2000 and share a sip with your companions. You want to tell the world, you want to check in with your family to say that you are “OK”.
It would be very poor if you were restricted to relaying a message though mission controllers. Simply “phoning home” for a chat wouldn’t be possible (the lag time between sentences would be at least 16 minutes). Could there be a way of sending emails? Possibly; voice messages will be fine too. But could our explorers set up a website or some “Mars blog” to document their travels? This could obviously be done remotely, with a terrestrial website, but there are strong arguments for a distributed Internet service on the Red Planet too. Can a “MarsNet” or “RedNet” be integrated with Earth’s Internet, establishing an “Interplanetary Internet”? Continue reading “Will the First Mars Settlements have Internet Access?”
It’s been a while since I last posted as I’ve been flying from the US to the UK and have only just gotten my office up and running. That’s not to say I haven’t been writing. On the Universe Today, I’ve posted quite a few articles ranging from quite an elaborate April Fools story (but not quite as elaborate as Virgin and Google’s Virgle prank), to a black hole hiding in the middle of Omega Centauri, to rocks rolling around on Mars… here’s a round up of the most interesting… Continue reading “Astroengine.com Roundup and Opinion”
This week has been an exciting week for astronomers. The largest explosion ever seen in the Universe was observed on Wednesday. This gamma ray burst, produced when a star collapses in on itself to create a black hole, is a record breaker. Not only is it the biggest explosion mankind has seen since records began, it is also the furthest and oldest “thing” we have ever observed… Continue reading “Daily Roundup: The Mars Curse and the Biggest Explosion in the Universe!”
It doesn’t get much better than this. A robotic orbiter snaps a photo hundreds of miles above the surface of an alien planet, capturing a geological event as it happens. Yes, we’ve seen Io’s immense volcanoes erupt, and we’ve seen huge storms rage on Jupiter, but often these large-scale planetary events are too massive for us to put into context and so we file them under “astronomy”. But, when we see an event like an avalanche on Mars, we can relate it with events on Earth, we have a “feel” for what this means. Suddenly an avalanche on Mars holds a special meaning to us; we instantly have a connection with other planets in our Solar System.
There has been much debate surrounding observations by the artificial satellites orbiting Mars, but with one discovery, the debate was… non-debatable. Liquid water was flowing (albeit quickly) across the Martian surface intermittently, creating river-like channels flowing down crater sides. But that was until a group of University of Arizona scientists tackled the situation. To their surprise it wasn’t water that was flowing, it was something entirely different… Continue reading “Daily Roundup: “It Ain’t Water On Mars” and Some Want UK Astronauts, But Others Don’t”
This is an interesting thought. We know that rocks from space can fall through the atmosphere and hit the ground as meteorites. But where do these rocks come from? Some come from old remnants of the early solar system, floating through space until they are captured by the Earth’s gravitational pull. Other meteorites come from other planets, ejected pieces of the planet crust (caused itself by a meteorite impact), escaping from the planets gravity by achieving “escape velocity”. We have found samples known to come from the Moon and Mars, but what about the other planets? Venus’ atmosphere is too thick to allow pieces of its surface to fly into space, but what about the first planet from the Sun, Mercury? Can bits of Mercury travel through space and land on Earth? Continue reading “Snippet: Can Pieces of Mercury be Found on Earth?”
We all know that space can be a dangerous place. Many safety measures are put in place by space agency scientists so astronaut’s lives are protected and mission success can be assured. Generally, some degree of certainty can be insured in near Earth orbit, protecting astronauts onboard the International Space Station and Shuttle missions, as most activities go on within the Earth’s protective magnetosphere. But in the future, when we establish a colony on the Moon and Mars, how will human life be protected from the ravages of solar radiation? In the case of Mars, this will be of special interest as should something go wrong, colonists will be by themselves… Continue reading “Protecting Future Mars Colonies From Solar Radiation: An Early Warning System”