Mars Rover Curiosity touchdown - and you think you've got latency issues!

Filed Under: Featured

Curiosity has landed on Mars.

Congratulations to NASA and the Jet Propulsion Laboratory!

Decelerating from 5900 metres per second (over 21,000km/hr or 13,000mph) to zero isn't difficult.

Crashing into a planet-sized object will do it in an instant.

But shedding that sort of speed and landing automatically and safely, through more than 120km of Martian atmosphere, within a 20km target zone, is an astonishing accomplishment.

For those of us charged with more modest-sounding tasks, such as releasing terrestrial software updates which work reliably, let's take this as evidence that you can produce software which works correctly on its first outing "in the wild".

And for those of us charged with delivering or receiving updates over the internet - and don't we love to complain about bandwidth and latency, no matter how much we have of the former, and how little of the latter! - let's spare a thought for the Mars Science Laboratory team.

The Mars Rover's direct-to-Earth data rate peaks at 32kbits/sec. In off-peak periods, the rate is as low as 0.5kbits/sec. As for latency, the round-trip distance is currently just under 28 light minutes, or roughly a light half-hour.

Gives a whole new meaning to the word ping.


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9 Responses to Mars Rover Curiosity touchdown - and you think you've got latency issues!

  1. chryss · 621 days ago

    Um, the distance between Earth and Mars varies between 4 and 20 light minutes. 14 is a good ballpark figure. But the roundtrip of a ICMP packet used in ping would be twice that, innit?

    • Paul Ducklin · 621 days ago

      Hmmm. I was under the apparently ill-considered impression that Mars was currently 7 light minutes away. But Wolfram Alpha assures me it's currently 13.8 (average 14.1), for an RTT of just under 28...I'd better update my faux-ping screenshot.

  2. kimjcastleberry · 621 days ago

    Wow, now THAT is quite the ping time! And yet... they made it work. In fact they almost made it look easy. When you don't know precisely where something is instant by instant, it can be nerve wracking and with pings like that... jeesh! Thanks for the reminder that we've got it good LOL!
    Kim
    PS: Remind me not to offer to colonize Mars until they get their own internet service kkthx!

    • Paul Ducklin · 621 days ago

      They didn't actually control the landing remotely. It was automated, which, in its way, is even more impressive. Move over, Google driverless cars.

      By the time they found out it had landed OK, it had been safely on the 'Martian surface for nearly quarter of an hour...

  3. Jerry Lee · 621 days ago

    Congratulations to the entire NASA team, this is like threading a needle with your eyes closed at arms length, and that would probably be easier. Great Work!!!!

  4. Bubbarae · 621 days ago

    Great Job, looking forward to what they will let us see from there.
    They could have used [a satellite provider] and got practice on how to deal with the ping time :-)

  5. Mike91163 · 620 days ago

    "...such as releasing terrestrial software updates which work reliably, let’s take this as evidence that you can produce software which works correctly on its first outing “in the wild”."

    A very telling comment, Paul; have we become so accustomed to poorly-written software that we celebrate a job done right the FIRST time? Have our quality expectations sunk that low?

    40 years ago, my late uncle used to program for Burroughs on really big iron; given the high operating costs, the programmers had to make certain their code was perfect-otherwise they would be looking for a new job.

    Nowadays, we EXPECT buggy software-so much so that we commonly say "wait for the 1st service pack"...sad state of affairs, isn't it?

    • Anonymous · 601 days ago

      Mike91163: Not necessarily. In many cases, more bugs can be the result of rapid development time which leads to faster innovation. Rapid innovation, even if it's sloppy initially, is often desirable.

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About the author

Paul Ducklin is a passionate security proselytiser. (That's like an evangelist, but more so!) He lives and breathes computer security, and would be happy for you to do so, too. Paul won the inaugural AusCERT Director's Award for Individual Excellence in Computer Security in 2009. Follow him on Twitter: @duckblog