Engineering | SCIENCE ON THE WING

October 13, 2012

Curiosity Gives A Wink And A Nod To JPL

Some of you are probably asking why are they using Morse Code code on the Curiosity Rover tires instead of just printing the letters JPL on the tires for Visual Odometry?

The original Engineering design and indeed the original Rover tested in the desert had tires that read JPL as they covered the landscape. Apparently, someone at NASA HQ (we are told by a reliable source) said “no, no, and no” to JPL on the tires. However, Visual Odometry remains an important part of this mission; a decision had to be made about how to accomplish this task.

Original engineering model tires in the back of a garage in the Mars Yard at JPL. photo credit: Hellwinger

Although we can’t say for certain, it would seem that using letters rather than random holes makes sense and given that there are three horizontal treads are devoted to odometric encoding on the Rover’s tires that would give them three letters to work with.

The rest is history as they say; a decision to use Morse Code gives the science and engineering team its Visual Odometry while conveying a sence of wonder and whimsy. For me, I like to think that every time Curiosity looks back at where it’s been, she sees a reminder of her first home, Jet Propulsion Laboratory.

October 13, 2012

Rovin’, Rovin’, Rovin’

This panorama is a great series of shots of Curiosity’s beefy tires. You notice the strategic holes in the tires? They are actually Morse Code, spelling out J – P – L, the acronym for NASA’s Jet Propulsion Laboratory. This unique pattern is used by Curiosity to accurately gauge how far it’s been by creating a unique pattern to use for visual odometry.

By using a known pattern, the Rover can look back and assess any number of situations; when traveling in a relatively featureless area, it can see where it has been, judge traction in high slippage areas, such as sand dunes and compare how far it has actually come along with its actual location. All of this by seeing this unique pattern in the Martian regolith!

. – – – (J), . – – . (P), . – .. (L) photo credit: NASA

To learn more about Visual Odometry visit:

http://www.nasa.gov/mission_pages/msl/news/msl20120829f.html

October 10, 2012

Calibration Targets

I’ve seen them referred to as “eyeshadow”, “paint” and “whatever those are” but in truth, they are an important part of the Mars Science Laboratory’s science mission: calibration targets.

One of the cal targets onboard Curiosity; the colored targets are doped silicone rubber photo credit: NASA/JPL

In the shake, rattle and roll of liftoff, flight and, in the case of Curiosity, the Mars Science Laboratory, seven minutes of terror as it falls to the planet’s surface, things can shake loose, degrade over time or stop working altogether. Calibration activities remain the best way to assure data collected are correct.

When conducting science remotely, it’s important that scientists are sure of what they are looking at and of various findings they make. In other words it’s one the ways scientists can say “how we know what we know”. The best way to achieve this is by including a well-known and characterized source to check your data against. These are referred to as calibration targets or cal targets.

There are many types of cal targets and infinite uses for them from calibrating the white balance on your digital SLR camera to telling a spacecraft light-years away that indeed, what it is looking at is white or, it is blue not white or that the chemical signature we are seeing is cadmium, which shows up as a particular color in the spectrum.

Whatever the composition of the target, the process is the same; a reading is taken from the cal target, from the subject and often from a third source. The readings from each of the sources are compared against each other and if they are in agreement, the instrument is correctly calibrated. If there is disagreement, data from each source is analysed to determine the location of the error.

Category: Engineering