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Mars Space Science

NASA Phoenix Mission Ready For Mars Landing 101

Posted by kdawson
from the boulder-dodging dept.
Several readers relayed the press release from JPL about the upcoming landing of NASA's Phoenix Mars Lander on May 25. It's going to set down in the north polar regions and look for indications of whether conditions have ever been favorable for microbial life. "Phoenix will enter the top of the Martian atmosphere at almost 21,000 kilometers per hour... In seven minutes, the spacecraft must complete a challenging sequence of events to slow to about 8 kilometers per hour... before its three legs reach the ground. Confirmation of the landing could come as early as 7:53 p.m. EDT. 'This is not a trip to grandma's house. Putting a spacecraft safely on Mars is hard and risky,' said Ed Weiler, associate administrator for NASA's Science Mission Directorate. 'Internationally, fewer than half the attempts have succeeded.'"
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NASA Phoenix Mission Ready For Mars Landing

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  • by blind biker (1066130) on Wednesday May 14, 2008 @05:48AM (#23400498) Journal
    I am sure a lot of slashdot readers are interested (I know I was) in how does this beast actually look like. So here's a very good article on the Phoenix lander with a couple of fantastic artistic concepts [scitech.ac.uk] based on the actual Phoenix.
  • by mrbluze (1034940) on Wednesday May 14, 2008 @05:56AM (#23400528) Journal

    This is not a trip to grandma's house. Putting a spacecraft safely on Mars is hard and risky.

    NASA: Oh my, Mars, what big craters you have!

    GrandMars: All the better to SWALLOW you with.. grrrr!

  • In seven minutes, the spacecraft must complete a challenging sequence of events to slow to about 8 kilometers per hour...

    Why reducing the box? Is there any reason to discard a higher speed landing?

    What if they find a way of slowing down to 16kmh, they abandon the mission?

    I'm not talking about considering compressing time continuum to extend those 7 minutes, but it seems there are possibilities that could still be considered, like hardening the legs, finding a softer spot to land, finding a lower landing spot to extend braking time, etc.

    • by ledow (319597) on Wednesday May 14, 2008 @06:46AM (#23400708) Homepage
      Because even at 8km/h you can do serious damage. Any lander has to be extremely light for takeoff from Earth and the transit to Mars, contain extremely fragile equipment, and end up there in one piece. "Bouncing" off Mars is not an option. That requires heavy, expensive materials, or some sort of complicated landed shield arrangement (e.g. giant inflatable bubble) that all add years of work and millions to the cost of the project. You could literally double or treble the cost of the entire project by "beefing up" the lander.

      Plus, it has to land under autonomous control, so you really have no idea how fast it actually landed or exactly where until several minutes after it has landed - so coming in a little too fast isn't a good option, neither is a stray patch of rock (there are few "soft spots" on Mars, by the way - it's mostly rock). Much better to land as gently as you can manage and do your braking manoevures in the "air" as you come down. You've got plenty of time, the physics are easier to calculate, and there's less to go wrong.

      The first few hours of a new lander's life on another planet are basically checking that everything still works, even with all the gentle landings in the world, things get broken that cost MILLIONS to put them up there. 50% of the things still never make it to the planet operational, even with all the good will in the world behind it. You want to spend MULTIPLES of the cost of the entire project on making the landings more difficult, more violent and less reliable when we can't even get half of what we send onto the planet successfully?
      • Because even at 8km/h you can do serious damage.
        Must be why I have such a bad feeling about this one. Lately the hard landings have been the most successful ones.

      • by Thanshin (1188877)

        Because even at 8km/h you can do serious damage.

        You could replace 8km/h for 4km/h in your entire reasoning and it would still stand, yet neither would address my point.

        I do understand that 8km/h is not an arbitrary limit. However, stating the landing problem as "There is only one chance! They absolutely must do this or everything will fail!" seems much more oriented to make the news more exciting than because of 8km/h being the perfect speed to put the lander on Mars.

        • Re: (Score:1, Insightful)

          by Anonymous Coward
          There is only one chance. A few things can be slightly off the mark, including the touchdown velocity, without losing the mission, but entry, descent, and landing has the least margin for error and most opportunities for outright disaster of any stage of the mission. They can't even delay it. Entry, Descent, and Landing is historically when the greatest number of mission failures occur.

          8 km/h is the target touchdown velocity. They'll come pretty close, probably with a couple km/h of that speed, but it pr
      • Re: (Score:3, Funny)

        by JosKarith (757063)
        "You want to spend MULTIPLES of the cost of the entire project on making the landings more difficult, more violent and less reliable when we can't even get half of what we send onto the planet successfully?"
        He must work for the government then...
    • by pipatron (966506)
      Maybe you should call some engineer at NASA and tell them about these ideas?
      • by Thanshin (1188877)

        Maybe you should call some engineer at NASA and tell them about these ideas?
        You mean I should call the journalist responsible for the press release and tell him to remove sensationalism when writing about serious matters.

        "the spacecraft must complete a challenging sequence of events"? Come on.
    • Re: (Score:2, Funny)

      by stoofa (524247)

      In seven minutes, the spacecraft must complete a challenging sequence of events to slow to about 8 kilometers per hour...
      Is anyone else picturing these challenging sequence of events as some engineer leaning on a red button with all his might while screeching "Brake, damn you!" at the top of his lungs?

      Maybe that's where the name idea came from...
    • by timmarhy (659436)
      this is why they are NASA engineer's sending craft to other planets, and your just some bozo posting stuff on /.

      not wanting to be harsh, but it doesn't sound like you've thought it through too much. try running your car into something at 16km/hr and get back to me.

      • by Thanshin (1188877)

        not wanting to be harsh, but it doesn't sound like you've thought it through too much. try running your car into something at 16km/hr and get back to me.

        So, your way of studying the landing speed limit of an object in another planet is crashing you car into objects.

        Well, now that you started with the ad hominem, let me do a follow up.

        Obviously just about everyone who reads this news understands the implications of a landing at 16km/h. Please make an effort to avoid thinking anyone might be under your intellectual level; you'll fail more often than not on that one.

        • Re: (Score:3, Funny)

          by JosKarith (757063)
          "So, your way of studying the landing speed limit of an object in another planet is crashing you car into objects."

          Well, it seems to work for particle physicists...
    • by ceroklis (1083863)
      The quote you give is overly dramatic. There is a sequence of events that must all happen at a precise time, and all succeed. Whether this sequence lasts 1 minute or 1 hour doesn't make it more or less difficult.

      The speed will not be twice what the spacecraft can withstand... for a good reason: They run simulations with varying entry angles, entry speeds, wind speeds, etc... to figure out the highest landing speed possible, and design for that.

      There is no need to harden anything if the design is soun
  • by Rosco P. Coltrane (209368) on Wednesday May 14, 2008 @06:57AM (#23400752)
    This is not a trip to grandma's house

    You've never met my grandma. As a kid, going there felt like a 25,000 mph trip, and there are still skidmarks from my shoes trying wildy to decelerate while my parents dragged me into the house. And about half of the times they tried taking me there, it failed too...
  • how many international missions with the end goal of landing on mars have there been?

    this guy makes it sounds like more than just a handful, and I can only recall 3.

    is there some vast international mars landing conspiracy that i'm unaware of?
    • Re:fewer than half? (Score:5, Informative)

      by jamesh (87723) on Wednesday May 14, 2008 @07:40AM (#23400926)

      is there some vast international mars landing conspiracy that i'm unaware of?


      Yes. The details are hidden away on wikipedia where you'll never find them! Some details:

      Mars 2 (1971): Landed but lost contact within minutes
      Mars 3 (1971): Same
      Viking 1 (1974): Landed and remained operational for 6 years
      Viking 2 (1974): Landed and remained operational for 3 years
      Phobos 1 (1988): Lost on the way to Mars
      Phobos 2 (1988): Got into orbit, took some photos, then failed

      The more recent ones you probably know about. To be fair, the Phobos 1 and 2 missions were planning to land on Phobos, not Mars, so maybe they don't count.
    • by PudriK (653971)

      I count only three non-American Mars landing missions, too: Russian M-71 and M-73, and Europe's Beagle 2 on Mars Express. But perhaps he was referring to the numerous international Mars orbit and flyby missions which have also failed.

      See Astronautix.com [astronautix.com] for details.

    • by cnettel (836611)
      Wikipedia whoring. [wikipedia.org]

      Quite a few included rovers/landers in one sort of another, and many failed. The first attempt was a Soviet probe in 1962, it didn't even leave Earth orbit properly, but it was a planned mission.

    • you've probably seen it by now, but just in case you haven't: just about 40 attempts [anl.gov]
  • by slinted (374) on Wednesday May 14, 2008 @07:03AM (#23400770)
    #space on irc.freenode.net is hosting a Phoenix Landing Party on Sunday, May 25 to share in this momentous occasion for planetary exploration. We'll be following NASA TV through landing, then ogling the raw images when they are released several hours later. Historically, #space has been a hub for collaborative efforts in image processing by the space enthusiast community (Mars Exploration Rovers, Huygens, etc). Hope you can join us!
  • by Anonymous Coward
    Ah. That'll depend on whos grandma we're talking about, wouldn't it?
  • by fantomas (94850) on Wednesday May 14, 2008 @08:02AM (#23401028)
    "21,000 kilometers per hour..." - Arggh! Ed (Weiler)! some of your guys are using metric units! Have a quick check round the lab and make sure they all are! Maybe the quiet guy in the corner in charge of retro rockets is still using miles not kilometres!

    I'm sure you have, but you know, we've been here before... ;-)
    • Re: (Score:2, Funny)

      by bsDaemon (87307)
      Good thing if Phoenix crashes, it'll just rise from the dead and reassemble itself, thereby completing its mission, good as new.

      Very good strategy on behalf of NASA, I'd say.
      • by RKBA (622932)
        Actually, Phoenix is itself a resurrection of the failed Mars Polar Lander [wikipedia.org] that I worked on a decade ago before my retirement from JPL (I wrote the firmware for the meteorology sub-system). I wish Phoenix well.
  • by cculianu (183926) on Wednesday May 14, 2008 @08:22AM (#23401168) Homepage
    From the media kit PDF about Phoenix:


    The helical antenna and a monopole UHF antenna, also mounted on the deck, will be used for relayt elecommunications during the months of operation after landing. The lander can send data at rates of 8,000 bits per second, 32,000 bits per second or 128,000 bits per second.


    Wow, that isn't a fast transfer rate. That's about 1KB/s, 4KB/s, and 16KB/s, respectively. I guess you don't need too much more -- but still, I bet it's slower than they would like. The high resolution camera alone probably produces images that are a few megabytes in size. Let's say the images are like 4MB -- Transferring 4 MB at 1KB/s takes about an hour!


    Given the slow xfer speeds and limited hardware they probably use -- I think it would be fun to be a programmer for NASA. That's one of the few applications where efficiency of communications, small memory footprint and efficient CPU usage probably still count for something.. I bet you everything they do when it comes to the software running on the lander tries to be as efficient as possible (especially communications-wise).

    Also, isn't there something like an few minutes of latency for light to reach us from Mars? You can't even really do any really realtime interaction with the onboard computer on the Phoenix lander.. Imagine typing into a shell and waiting a minute for your characters to appear! Ouch! So I bet you they have to premeditate a lot of the changes they make to the software or operating environment way a head of time -- they probably just upload scripts of commands when updating the software or filesystem, etc.


    I wonder how much freedom they give the people communicating with the lander. Do they triple-check every command sent to it to make sure noone does the inadvertent 'rm -fr /'?

    • by GbrDead (702506)
      Imagine typing into a shell and waiting a minute for your characters to appear!

      Actually, this was happening quite frequently back in the dial-up days.
      • by sconeu (64226)
        Dialup schmial up.

        This happened all the time back in '83 and '84 on a VAX 11/780 at UCSC. Come the end of the quarter, the VAXen would all be overloaded (we're talking load averages over 30, with spikes up to 70).

        You'd type a command, go away and get a cup of coffee, and maybe when you got back, you'd get an acknowledgement that you actually did something.

        However, in tribute to the 4.2BSD guys (original Berkeley, not Open/Net/FreeBSD), even with this insane overload, the VAX... Did... Not... Crash.
    • Re: (Score:2, Interesting)

      by silverpig (814884)
      "Also, isn't there something like an few minutes of latency for light to reach us from Mars? You can't even really do any really realtime interaction with the onboard computer on the Phoenix lander.. Imagine typing into a shell and waiting a minute for your characters to appear! Ouch! So I bet you they have to premeditate a lot of the changes they make to the software or operating environment way a head of time -- they probably just upload scripts of commands when updating the software or filesystem, etc."
    • by tpheiska (1145505)

      I wonder how much freedom they give the people communicating with the lander. Do they triple-check every command sent to it to make sure noone does the inadvertent 'rm -fr /'?

      Actually they've messed up a satellite this way. A detaild explanation can be found here [nasa.gov], quote "A modification to a spacecraft parameter, intended to update the High Gain Antenna's (HGA) pointing direction used for contingency operations, was mistakenly written to the incorrect spacecraft memory address in June 2006. The incorrect memory load resulted in the following unintended actions ...". It's actually pretty amazing that they've managed to reconstruct the whole sequence of events, most likely by usin

    • Re: (Score:3, Interesting)

      by ChrisA90278 (905188)
      The typically have a model of the spacecraft in the lab. any change to the software gets uploaded and tested in the lab. There will be quite a bit of formal testing using a detailed written test plan. Then there is some kind of a change review bord that meets and reviewis the tests and the plan. Finally the changes get packaged up. The they test the upload procedure on the lab simulator. Then finaly the change is uploaded.

      Typing into a shell is not only slow but far to risky. Everything gets tested fo
      • bord? reviewis? That you, Golum?

        the process is very slow going and productivity runs at well under 200 lines of code per month per engineeer.
        They inherited the Longhorn / Vista staff?
      • by muhadeeb (1062676)
        They can do better than that. They could have outsourced the code to either apple or microsoft or go open source. With open source, it could be cheaper.
  • Several readers (Score:1, Offtopic)

    by esocid (946821)
    I had no idea I was more than one person [slashdot.org].
  • Is it me or do the solar panels on the Phoenix lander look remarkable like the http://en.wikipedia.org/wiki/Umbrella_Corporation [wikipedia.org]Umbrella Corporation logo? What with the reputation of Mars (Ghosts of Mars, The Red Planet, Doom, that one outer limits, etc) I'm not too sure I like a resident evil probe up there....
  • by HoneyBeeSpace (724189) on Wednesday May 14, 2008 @09:58AM (#23402250) Homepage
    Here is a great scorecard of all missions to mars showing which have succeeded, which have failed, and why: http://www.bio.aps.anl.gov/~dgore/fun/PSL/marsscorecard.html [anl.gov]
  • half as many (Score:3, Insightful)

    by sgt scrub (869860) <saintium@y a h oo.com> on Wednesday May 14, 2008 @02:12PM (#23406918)
    wouldn't there have been at least half as many trips to mars if they weren't so hell bent on trying to figure out if there is life there? could we get on with the process of making it a habitable place instead of waisting trips on "theological i told you so" science projects?

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