Skip to main content

Why don't they just..?

It seems every time I come across a story about the Mars Curiosity rover there will be many people commenting on the technology used starting with "Why don't they just..?" and usually pointing out things like: the processor in their smart phone is way faster than the one of Mars, or they have way more memory on their iPad, or their digital camera is way better than the one sending back pictures. These "Why don't they just..?" questions are both annoying and to be expected.

Annoying because the underlying thought is "Those NASA/JPL guys are so dumb LOL" and to be expected and encouraged because we wouldn't make any progress without asking questions and, in particular, asking why.

But it doesn't take much research to find the answer. (Even though I'm tempted to answer: "Because it's on friggin' Mars, doofus!")

1. The Mars Science Laboratory project was started eight years ago in 2004. So, all the technology on it is at least eight years old.

2. The trip to Mars means flying in an area with high amount of radiation (from things like cosmic rays, all manner of stuff flying out of the Sun and the Van Allen radiation belt). That means all the electronics needs to be radiation hardened. So, you don't start with just whatever you can get from Fry's Electronics in 2004. You need specifically radiation hardened components like the RAD750 processor in Curiosity.

3. You need to be a bit conservative. The thing you're sending to Mars is going to be on its own and unrepairable. It had better work. So, you're likely to reuse components and techniques that you know work. It has been reported that the skycrane used to land Curiosity used components derived from the 1970s Viking landers and algorithms used on the Apollo craft.

4. And once you've worried about radiation hardening, reliability, and weight you need to worry about bandwidth back to earth. It's no good taking gigapixel photographs if you can't get them back to Earth. For example, Curiosity can communicate with the Mars Reconnaissance Orbiter for a few minutes per day at 2Mbps and with Mars Odyssey at 256kbps.

But rather than explaining all this stuff, I think there's a better way: build, land and operate a rover here on Earth.

The Rover Challenge

I've done one high-altitude balloon flight and watched the progress of many others. Although going to Mars is a very different situation there are similar challenges: weight, environment, communications, landing.

A good way to see how hard it is to build and operate a rover would be to build one designed for operation in an inhospitable part of Earth. Launch it via a high-altitude balloon with parachute descent and then operate it without GPS over a slow, high latency radio link.

It would actually be a fun project. On a balloon you can probably have about 2kg of payload maximum for your rover. Now imagine 2kg weight budget for a semi-autonomous rover that would be dropped into a desert in the South Western USA, or the Sahara, or the Australian outback.

The rover would have to withstand high tempertures, dust, and wind; operate on a perhaps unstable sandy ground; communicate using HF radio; and operate without a human touching it.

To me it sounds like a fun challenge. Anyone else?


Unknown said…
Sending a rover to sahara by a balloon (or even better, a zeppelin) is by far the most wicked yet doable projects I've ever seen.
Anonymous said…
I've always quite wanted to land a little rover into some kind of toxic and human-unfriendly semi-active volcano mouth.

I assume bonus points for retrorocket-assisted descent?
carbonfeed said…
+1 for into the mouth of a volcano, if it's going to be a one way trip, make it a great one!
wisdomdata said…

Somewhere like this near Coober Pedy - its like mars with trees and retrieval could be arranged.
Unknown said…
I would absolutely be up for devoting time and resources to such a project. The volcano idea would be pretty damn absurd.
Unknown said…
This comment has been removed by the author.
What happens if it happens to land in a really inhospitable environment, like, say, a South London council estate?
What happens if it happens to land in a really inhospitable environment, like, say, a South London council estate?
Anonymous said…
So why did they push a software update remotely, and not just switch to it remotely?
Kerry Wilson said…
That does sound like a fun idea.

I assume there is also limited power. I don't think we want to take 8 years to build a robot just to have it last a month b/c the geek in us wanted to put the latest and greatest multicore processor in it.
Ricardo Tomasi said…
@catch22 according to interviews, limited storage, and they were still working on it while the rover was on the way to mars.
Unknown said…
great great great idea there. I can foresee the heyday of Arduino.
Henk said…
I'm doing robotic project right now, and weight - is not only restriction. Also - power that your battery could generate. And that power restricted by weight too. So if you want to have 50Ah, with battery weight ~ 100-200gr - it is just impossible.
Brian Kuehn said…
I'm actually closer to the arctic circle... That is a pretty inhospitable place!
Unknown said…
This comment has been removed by a blog administrator.
Peter Wallhead said…
The Rover Challenge sounds awesome! I'm asking around my friends now to see if something like this is doable.
Matthew Hall said…
Curiosity does not even have NFC ;-)
Traveller said…
What about funding it via Kick Starter as an open source learning project
tbohon said…
One of the neatest ideas I've seen floated yet. As someone with a scientific curiosity and background in computer simulation and also as a ham radio operator I'm virtually salivating here ... :)
Unknown said…
OMG, thats the coolest think I ever thought of! A journey to the arctic circle ...
mr_geronimo said…
i'd send mine to Detroit..
Dan Frederiksen said…
John, when a single geek does what you propose on a shoestring budget with much higher image quality and even bandwidth despite not having access to a satellite network like nasa could have done, will you then wake up and realize how pathetic nasa is?
what Curiosity is doing would not be out of place in 1970. it is that pathetic. indeed it could be outdone with live video in 1970
A_flj_ said…
My approach would be different: build and launch an entire horde of small, inexpensive robots which can fix each other, scavenge on each other for parts, and collaborate on various tasks.

Sort of deploying a mobile cloud, instead of a single powerful server, in terms of software.

It would be a real challenge for the software developers, but not really that much of a challenge for the hardware developers, IMO.

Comming to think of it, the rasp.pi I just received plus a lego mindstorm make a good prototyping platform for prototyping ...
Keith Chuvala said…
> Dan Frederiksen said...

"...when a single geek does what you propose on a shoestring budget...."

Pray tell, who, and what project, are you referring to?

Full disclosure: I've worked for a NASA contractor for over 13 years. I have observed very little evidence of "pathetic" over that time.

Well, unless you're talking about political appointees at the top end of the agency, I guess....

Popular posts from this blog

Your last name contains invalid characters

My last name is "Graham-Cumming". But here's a typical form response when I enter it:

Does the web site have any idea how rude it is to claim that my last name contains invalid characters? Clearly not. What they actually meant is: our web site will not accept that hyphen in your last name. But do they say that? No, of course not. They decide to shove in my face the claim that there's something wrong with my name.

There's nothing wrong with my name, just as there's nothing wrong with someone whose first name is Jean-Marie, or someone whose last name is O'Reilly.

What is wrong is that way this is being handled. If the system can't cope with non-letters and spaces it needs to say that. How about the following error message:

Our system is unable to process last names that contain non-letters, please replace them with spaces.

Don't blame me for having a last name that your system doesn't like, whose fault is that? Saying "Your last name …

All the symmetrical watch faces (and code to generate them)

If you ever look at pictures of clocks and watches in advertising they are set to roughly 10:10 which is meant to be the most attractive (smiling!) position for the hands. They are actually set to 10:09.14 if the hands are truly symmetrical. CC BY 2.0image by Shinji
I wanted to know what all the possible symmetrical watch faces are and so I wrote some code using Processing. Here's the output (there's one watch face missing, 00:00 or 12:00, because it's very boring):

The key to writing this is to figure out the relationship between the hour and minute hands when the watch face is symmetrical. In an hour the minute hand moves through 360° and the hour hand moves through 30° (12 hours are shown on the watch face and 360/12 = 30).
The core loop inside the program is this:   for (int h = 0; h <= 12; h++) {
    float m = (360-30*float(h))*2/13;
    int s = round(60*(m-floor(m)));
    int col = h%6;
    int row = floor(h/6);
    draw_clock((r+f)*(2*col+1), (r+f)*(row*2+1), r, h, floor(m…

The Elevator Button Problem

User interface design is hard. It's hard because people perceive apparently simple things very differently. For example, take a look at this interface to an elevator:

From flickr

Now imagine the following situation. You are on the third floor of this building and you wish to go to the tenth. The elevator is on the fifth floor and there's an indicator that tells you where it is. Which button do you press?

Most people probably say: "press up" since they want to go up. Not long ago I watched someone do the opposite and questioned them about their behavior. They said: "well the elevator is on the fifth floor and I am on the third, so I want it to come down to me".

Much can be learnt about the design of user interfaces by considering this, apparently, simple interface. If you think about the elevator button problem you'll find that something so simple has hidden depths. How do people learn about elevator calling? What's the right amount of informati…