Since the 1960s and 70s, scientists have come to view Mars as something of a “dead planet.” As the first close-up images from orbit and the surface came in, previous speculation about canals, water, and a Martian civilization were dispelled. Subsequent studies also revealed that the geological activity that created features like the Tharsis Mons region (especially Olympus Mons) and Valles Marineris had ceased long ago.
However, in the past few decades, robotic missions have found ample evidence that Mars is still an active place. A recent indication was an image taken by the Mars Reconnaissance Orbiter (MRO), which showed relatively fresh landslides in a crater near Nili Fossae. This area is part of the Syrtis Major region and is located just north of the Jezero Crater (where the Perseverance rover will be landing in six weeks!)
In many ways, Mars is the planet that is most similar to the Earth. The red world has polar ice caps, a nearly 24-hour rotation period (about 24 hours and 37 minutes), mountains, plains, dust storms, volcanoes, a population of robots, many of which are old and no longer work, and even a Grand Canyon of sorts. The ‘Grand Canyon’ on Mars is actually far grander than any Arizonan gorge. Valles Marineris dwarfs the Grand Canyon of the southwestern US, spanning 4,000 km in length (the distance between LA and New York City), and dives 7 kilometers into the Martian crust (compared to a measly 2km of depth seen in the Grand Canyon). Newly released photos from the High-Resolution Imaging Science Experiment (HiRISE) aboard the Mars Reconnaissance Orbiter (MRO) reveal a stunning look at eroding cliff faces in Candor Chasma, a gigantic canyon that comprises a portion of the Valles Marineris system.
Just like Earth, Mars undergoes seasonal changes due to its axial tilt. And while summer heat on Mars can’t compare with Earth’s, along with the Martian summer warmth comes an increase in small whirling storms known as dust devils.
NASA’s Mariner 9 was the first spacecraft to orbit another planet when it reached Mars in late 1971. It got there only a few weeks before the Soviet Union’s Mars 2 and Mars 3 spacecraft, despite being launched 11 days later than those missions. Unfortunately, there was a major dust storm when Mariner 9 arrived, and NASA had to wait until January before the spacecraft could get good images.
When it did get those images, they revealed a surprise: volcanoes and lava flows cover large portions of the Martian surface.
Impact craters have been called the “poor geologists’ drill,” since they allow scientists to look beneath to the subsurface of a planet without actually digging down. It’s estimated that Mars has over 600,000 craters, so there’s plenty of opportunity to peer into the Red Planet’s strata – especially with the incredible HiRISE (High Resolution Imaging Science Experiment) camera on board the Mars Reconnaissance Orbiter which has been orbiting and studying Mars from above since 2006.
I remember the Summer of 1997 when a shoebox-sized Mars rover literally broke the Internet.
Sojourner – the first rover we sent to another planet – had just landed on Mars in a giant space airbag bouncing along the surface to a safe stop. The Internet was new. And I was a young space enthusiast with a dial-up modem. For the first time, images from a space exploration mission were beamed to an audience that was connected online. Now we use the term “broke the Internet” as a hyperbolic phrase for various Internet phenomena, but interest in the Mars mission in 97 drove so many hits to NASA mirror servers around the world that global web traffic was disrupted. Patiently I watched as, line by line, orange sky to red stone, the first image posted by NASA loaded on my screen…it took about an hour. Each line resolved was like my own exploration of the planet. And finally, the landing site, in “real time”, was revealed to me and the entire world all at once. What would we discover together?
The HiRISE (High-Resolution Imaging Science Experiment) instrument on NASA’s Mars Reconnaissance Orbiter (MRO) has given us a steady stream of images of the Martian surface. It’s been in orbit around Mars since March 2006, and has greatly outlived its intended mission length.
One of the latest Hi-PODs, or HiRISE Pictures of the Day, is this one, of sedimentary rock on Mars being eroded away.