Late last night, Mars Science Laboratory (MSL) Curiosity successfully navigated its way through Seven Minutes of Terror and touched down on the surface of the Red Planet, heralding a new age of extraterrestrial exploration that will eventually result in the human colonization of Mars.

The first photos from Curiosity are starting to trickle in (right), and very soon we’ll start to see scientific data gathered by Curiosity’s on-board science lab, so I thought it would be a good time to discuss the hardware and software that actually makes MSL Curiosity possible.

Hardware

At the heart of Curiosity there is, of course, a computer. In this case the Mars rover is powered by a RAD750, a single-board computer (motherboard, RAM, ROM, and CPU) produced by BAE. The RAD750 has been on the market for more than 10 years, and it’s currently one of the most popular on-board computers for spacecraft. In Curiosity’s case, the CPU is a PowerPC 750 (PowerPC G3 in Mac nomenclature) clocked at around 200MHz — which might seem slow, but it’s still hundreds of times faster than, say, the Apollo Guidance Computer used in the first Moon landings. Also on the motherboard are 256MB of DRAM, and 2GB of flash storage — which will be used to store video and scientific data before transmission to Earth.

The RAD750 can withstand temperatures of between -55 and 70C, and radiation levels up to 1000 gray. Safely ensconced within Curiosity, the temperature and radiation should remain below these levels — but for the sake of redundancy, there’s a second RAD750 that automatically takes over if the first one fails.

Software

On the software side of things, NASA again stuck to tried-and-tested solutions, opting for the 27-year-old VxWorks operating system. VxWorks, developed by Wind River Systems (which was acquired by Intel), is a real-time operating system used in a huge number of embedded systems. The previous Mars rovers (Sojourner, Spirit, Opportunity), Mars Reconnaissance Orbiter, and the SpaceX Dragon spacecraft all use VxWorks. VxWorks also powers BMW iDrive, the Apache Longbow helicopter, and the Apple Airport Extreme and Linksys WRT54G routers (really).

I said that VxWorks is 27 years old, but that’s a bit unfair: The initial release was in 1985 (around the same time as MS-DOS 3.0), but it has been in constant development since then, reaching v6.9 last year. Why does Curiosity use VxWorks? It’s reliable, has a mature development toolchain, and presumably its low-level scheduling and interrupt systems are ideal for handling real-time tasks like EDL (entry, descent, and landing; aka, seven minutes of terror).

Instrumentation

MSL Curiosity is quite literally a science lab on wheels, and as such its instrumentation armament is rather insane. There are 17 cameras in total, four of which (the highest-resolution ones) are equipped with 1600×1200 (2-megapixel) CCD sensors. The camera that we’re most interested in is MastCam, which will take high-res true-color images of the Martian landscape, and 720p video at 10 fps. Looking down rather than out, the Mars Hand Lens Imager, which is attached to the robotic arm, will take microscopic images of the soil and rock beneath Curiosity.

Science-wise, the most important camera is probably ChemCam, which will vaporize rocks and soil with an infrared laser, and then use spectroscopy to analyze the sample. There are lots of other spectrometers on-board, too, a radiation monitor, a water/hydrogen detector, and an instrument suite (chemistry set?) that will analyze samples that are scooped up from the ground.

Until MastCam is raised — which should happen in the next day or two — most of the imagery we will receive from Curiosity comes from the hazard avoidance cameras, or Hazcams. These are grayscale cameras attached to the four corners of Curiosity, which build up a 3D map of the rover’s surroundings. This map is then used to autonomously navigate around hazards (rocks larger than 75cm or so, chasms, little green men, etc.)

Communication

Beyond the landing procedure — which we’ve discussed in the past — by far the coolest aspect of Curiosity is that we’re controlling a human-made robot that’s up to 250 million miles away, and in turn it will send back terabytes of data over the next few years.

As you can imagine, transmitting data over 250 million miles requires a lot of power. Curiosity generates 125 watts of electricity from a 2000-watt plutonium-based radioisotope thermoelectric generator. Waste heat is used to keep the MSL’s systems at optimum temperature.

Curiosity can either communicate directly with Earth’s Deep Space Network (DSN) antenna via an X band (8GHz) link, or it can use a UHF (300MHz-3GHz) transmitter to relay signals through Mars Odyssey and Mars Reconnaissance Orbiter, which orbit a few hundred miles above Curiosity. Because it’s a lot cheaper for Curiosity to use UHF, and because the Mars Reconnaissance Orbiter has a very-high-speed 6Mbps X band antenna, relaying will be Curiosity’s main way of sending data back to Earth.

The next few days

While we’re fairly certain that Curiosity made a perfect landing on Mars, NASA will now spend the next few days confirming it. Once mission control is convinced that Curiosity hasn’t landed on the edge of a crevasse or a pit of quicksand, the mast, robotic arm, and high-gain antenna will be deployed. In a week or so, we should be looking at the first high-res panoramas created by MastCam. In the next few days we’re also expecting a photo taken by the Mars Reconnaissance Orbiter of Curiosity’s descent and landing. If you didn’t know, MRO is equipped with HiRISE, an 800-megapixel camera that shoots 2-gigabyte photos.

Eventually, we’ll even get some movies of Curiosity roving across the surface of the Red Planet at a heady 90 meters per hour. I wouldn’t be surprised if, in a few years, you can see Curiosity: The Movie at your local IMAX theater.

Updated: Added: Multiple photos taken by Curiosity; a new photo of Curiosity, taken by Mars Reconnaissance Orbiter, during descent; and a video captured by Curiosity itself, during its last two minutes of descent.

Updated again: Added a very cool photo of the Curiosity landing site, taken by the Mars Reconnaissance Orbiter. You can see all the debris, including the sky crane, heat shield, etc. Also added the first high-resolution image of the Martian surface, taken by one of the black and white navigation cameras.

Read: Curiosity, and the future of human space exploration