Big Wheeling for Extreme Science - the Mars Science Laboratory

Hogg
by Robert Hogg
Robotics Engineer

Mars Science Laboratory is a mission to create and send to Mars the largest, most capable and most exciting rover that has been sent to another planet to date. It will be a remote robotic scientist that will help us investigate our most Earth-like neighbor in the solar system. It is literally a mobile laboratory — the size of a car, with a wide array of science instruments that will help us determine whether Mars has the capability to support life, both in the past and in the present.

Most of my work at JPL has been in the area of research robotics, small projects with very focused goals, such as the Urban Robot project, the Spiderbot, and many others. These robots were created using a small team of engineers who each covered a wide area of responsibility such as mechanical, electrical, and different areas of computer science for perception and navigation.

Here is a great animation showing everything that Mars Science Laboratory will accomplish, as well as all the different mechanisms and systems that will have to work remotely a hundred million miles away on Mars.

At times, to get one of these robots working right we would “hack” together a solution, and get it implemented in a very short amount of time! By throwing our energy and ideas into each project, we could push the cutting edge of different technologies and robotic capability that could then be used by future projects and researchers.

In contrast I’m now working on the motor control system of the Mars Science Laboratory mission, which as opposed to research is a “flight project” (it’s going to fly!). This is quite a different experience than the research area - the mission is kind of like taking the goal or purpose of the robot, breaking it down into a million pieces, and putting every piece under a microscope to make sure everything will work absolutely perfectly. Instead of 10 or fewer engineers each working on the different subsystems of the robot, we have hundreds of engineers and scientists who are planning, designing, developing, manufacturing, testing and in general creating a very complicated remote-sensing system.

MLS
Latest Mechanical Integration Progress

Sending a robot of any kind to another planet is a completely different story than running any such thing on Earth. For one thing, the robot must operate within very extreme temperatures and handle harsh exposure to the sun’s rays. Future robots may have to deal with steep or challenging terrain, or even a lack of a solid surface such as on Titan, Saturn’s largest moon. And throughout all this, the robot has to work perfectly and stay in communication with Earth. There is no control-alt-delete button to handle software crashes, and no technician around who can run out to push the big red reset button. In other words, if you’re going to run a robot on another planet, it has to land unharmed, work the first time, and run correctly every time you command it to do something, so that you’re guaranteed to get back the vital science data you’re after.

    9 Responses to “Big Wheeling for Extreme Science - the Mars Science Laboratory”

  1. vahid Says:
    September 30th, 2008 at 3:33 am

    Hi Robert,
    What do you mean exactly ?

    the mission is kind of like taking the goal or purpose of the robot, breaking it down into a million pieces …

    I can’t understand the relation between the Motor Control System and this phrase !!

    Hogg says:
    Hi Vahid, What I mean to say is that any robot that is being sent to another planet requires much more analysis and design than anything that will be operating on Earth. That means each system or subsystem of the robot, right down the nuts and bolts and lines of code, gets a lot of design attention, review, and testing to make sure there are no problems and no bugs that will show up when the robot is on Mars. The Motor Control System is just one piece of the overall robot but it itself has thousands of mechanical parts, electronics pieces and lines of software that all have to work with no problems - and each of these is put under a “microscope” before launch to make sure they will all work correctly together.

  2. Montana Says:
    September 30th, 2008 at 8:05 pm

    Wow - This is a great article and I wish you luck. Sounds like quite a project.

  3. bri Says:
    October 1st, 2008 at 9:27 am

    Great post Robert. I’m really looking forward to MSL’s contributions to the recent wealth of data about Mars. That’s quite a touch down sequence. How unique is it?

    Hogg says:
    Thanks for the question bri. Well we’ve used similar landing engines in the past, like on the Viking landers. However parts of it are new or different, for example the brushless motors. One part that is entirely new and exciting is the sky crane part of the landing (where the robot is lowered on wires down to the ground). That has never been done before on Mars but similar designs have been used here on Earth many times with helicopters and such, which is where the name comes from.

  4. PDS Says:
    October 1st, 2008 at 12:30 pm

    WOW, great blog. I’m sure you are going to do an excellent job with the Motor Control System.

    I would be very interested in hearing from those involved in the Entry-Decent-Landing of the MSL.

    Hogg says
    No problem, see posts from my colleague, Ravi Prakash.

  5. George Morfopoulos Says:
    October 1st, 2008 at 7:34 pm

    Very Interesting! More details please. I understand that there would be special challenges to operate equipment that remotely, and in a space environment. Would you be able to post some examples and perhaps compare them to earth vehicles by comparison? Something familiar that we could use to understand the scale of the differences better?

    Hogg says
    Thanks for the question George. An example of a difference between operating in our comfortable Earth environment and the extremes of Mars is in the area of motor gearboxes. We typically use some kind of grease to keep the gears lubricated and run smoothly.
    However in the low-temperature environment of Mars (down to -50 or -90 C where we’re going) any such grease would freeze and seize up the whole assembly. so heaters have to be used to keep the warm and moving. Additionally the large temperature swings cause an unusual amount of expansion and contraction in between the gears due to the steel parts literally changing size. This causes extra play which translates up the gear train to affect the swing and control of the robot’s arm and mast, resulting in “deadbands” of control that have to be handled by the control system and software - which is a whole study and realm of testing in and of itself!

  6. Tony Procopio Says:
    October 4th, 2008 at 6:08 pm

    My incredibly talented cousin ! I am extremly proud of you and your accomplishments ! Keep pushing the boundries. They are there to be explored and developed and your just the type that will accomplish it ! Keep up the awesome work and I look forward to reading more of your trial and tribulations !

    Your Cousin

    Tony

  7. AUDREY SIOBHAIN Says:
    February 23rd, 2009 at 5:08 pm

    Thanks for sharing all of knowledge with all of us!
    blessings!

  8. Recchia Says:
    January 14th, 2010 at 8:20 pm

    It’s so cool, thank for your post

  9. Voelker Says:
    May 20th, 2010 at 8:04 am

    Hey, this is an awesome post. I really think you should do more like this, I’ll be sure to visit your blog again to see your new stuff. Thanks.

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