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Discussion in 'Hobby Electronics' started by Don McKenzie, Aug 6, 2012.

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  1. Don McKenzie

    Don McKenzie Guest

  2. Jon Kirwan

    Jon Kirwan Guest

    I started watching the NASA channel about 4 hours ago and
    stayed with it. (Still watching, while they are doing the
    news conference event and just finished congradulating each
    member of the EDL team (entry, descent, and landing.)

    Australia was part of this success, as well -- at least in
    terms of participating in the very much needed communications

    What impresses me the most is that this trip was about 350
    million miles, ending in a tight coordination with two
    orbiting satellites, the ODY and MRO, and deploying novel
    technologies to land a 1 ton vehicle (if I heard correct.)
    Hard to believe that all of this could come together as well
    as it did.

  3. Phil Allison

    Phil Allison Guest

    "Jon Kirwan"

    ** Wonder if " Howard Wolowitz " will be offering any chubby babes the
    chance to drive this little BUGGY on Mars ??

    ..... Phil
  4. Don McKenzie

    Don McKenzie Guest

    Try and get people to believe that the Concord and 747 first flew in 1969, or that the B52 proto took to the air in 1952.

    BTW The B52 is still a current work horse.
    Only 6 new heads and 3 new handles. :)

    Don McKenzie

    Web's best price on Olinuxino Linux PC:

    The World's Cheapest Computer:
    DuinoMite the PIC32 $23 Basic Computer-MicroController
    Add VGA Monitor/TV, and PS2 Keyboard, or use USB Terminal
    Arduino Shield, Programmed in Basic, or C.
  5. I thought the over-hyped commentary during the landing and especially
    in pre-landing videos (like the "Seven Minutes of Terror") was
    embarassing and made the design engineers and mission planners sound

    The commentators kept yammering on about how there was "zero margin
    for error", and how "absolutely everything has to work right".

    Really? A design with _zero_ safety margin? Who signs off on a
    system design or mission plan like that?

    I'm pretty sure that the "absolutely everything has to work right" is
    also bullshit. I heard several people who seemd know know which way
    was up talking about redundancy in the hardware design, the software
    design, and in the mission planning itself.

    The blockbuster-movie-preview-preview-style-over-hyped-bullshit just
    detracted from what in reality was an utterly brilliant job. Even
    though nothing _did_ go wrong (AFAICT), and they hit center of the
    bullseye, I'm confident that there was both redundancy and margin for
    error designed/built into almost everything.
  6. swanny

    swanny Guest

    Same thing crossed my mind. What if something that was ejected plonked
    itself on top of the landed craft.
  7. Phil Allison

    Phil Allison Guest


    ** The first successful landing of a Mars probe complete with small "rover "
    vehicle was in December 1971.

    The Soviets reached the moon with a probe in September 1959.

    .... Phil
  8. Sylvia Else

    Sylvia Else Guest

    Even the animated video of the skycrane clearly shows the rockets in
    pairs, with only one of each pair in use.

  9. Walter Banks

    Walter Banks Guest

    I like many watch the landing coverage. There are two
    things that really impressed me.

    1) The navigation to get them there on a really small landing

    2) With all of the technology in the systems to land this
    successfully, one number still is impressive. There were still
    250 single point possible failures. The math against it working
    was astronomical. If there was anyone involved reading
    this I am all ears and you have my congratulations.

    Listing to the systems readout after the landing showed it
    almost everything was nominal.

    Congratulations all

    Walter Banks
  10. Jon Kirwan

    Jon Kirwan Guest

    Dr. Adam Steltzner probably deserves very high praise. And I
    very much appreciated his sincere comments about others on
    his team (some, he said, were better deserving and more
    skilled than he) to have been given the honor he was given in
    leading the EDL team who worked so hard at perhaps the more
    problematic parts of the problem starting 7-8 years ago. I'm
    sure he slave-drove these people, but he also was provided
    the source of confidence and the energy to push through
    problems with consistent and overwhelming force.
    Oh, what I wouldn't do to get my hands on the optical design
    of those devices and some ideas about sourcing parts here. I
    have worked with spectrophotometers for decades now, going
    back to the mid 1980's. Some of it expensive, but all of it
    only to commercial standards. I started using the Ocean
    Optics (because they were CHEAP) as soon as they first came
    out with something decent. (Most of my work was in the
    visible, near UV, and near IR -- but for very different
    applications.) I still have some decent setups here and I've
    designed some devices that can be made for only a few
    dollars, and wavelength calibrated for $8 more, so that high
    school students could actually built their own real-world
    equipment that could genuinely "do science" and meet
    calibration standards. No intensity calibration, though,
    sadly. That costs money to do. (Unless you have a suggestion
    about how to do it on the cheap?)
    I think few people understand just what this kind of team
    work means inside, how much it changes who you are, and what
    it means when the work is suddenly handed off and you scatter
    to the winds. Perhaps actors doing a long-running play, like
    Les Miserables, would understand when the play breaks up
    (though that one never seems to.) It's years of hard work
    building up a team that in the end works superbly together
    and has learned how it must be that each person makes up for
    the deficits of each other, while capitalizing on their
    strengths, into a whole unit that from the outside is totally
    functional and complete.... only to have it dismantled
    suddenly at the end. Or, at least, the serious threat of it.
    All that has been so hard-won....

    I feel for all here.

  11. Jon Kirwan

    Jon Kirwan Guest

    Of all those single points of failure, the ones that worried
    me the most were the pyros. You can test a lot of things --
    like the 65,000 pounds of force the parachute had to bear.
    But you can't test the ACTUAL pyros you will use. No matter
    what you do, the ones you place in there can't have been
    tested. We know how to make explosives of great uniformity,
    of course. But all of that has to go into a system and it
    must fire exactly correctly, under buffeting circumstances,
    without a single point of failure in a single pyro. Just one
    and that is it. Not that the rest wasn't also difficult. But
    some of the things, since as the novel use of an imbalance in
    weight distribution in order to permit direction control
    during entry, can have errors in one part of the software be
    compensated by the outer control loop in another part. So
    even there, there is a backup hope. But the pyros either
    work, or don't. That's what I was watching mostly for, though
    the rest was also sincerely knuckle-whitening as well.

  12. josephkk

    josephkk Guest

    I have met some of these people, and i couldn't tell the difference in a
    few moments talking to them. Just the same they seem to be made of
    sterner stuff than Dale six-pack.
  13. However, you can have redundancy in some types of pyros such as wire
    cutters and other release mechanisms. Whether such redundancy is worth
    the extra pyro weight, cabling and switching is a matter for experts
    to decide.

    Mark Borgerson
  14. Right up there is the first flight of the A-12 (predecessor to the SR-
    71) in 1962. Of course, only a limited number of people really knew
    about it at the time! ;-)

    Mark Borgerson
  15. Geoff

    Geoff Guest

  16. Jon Kirwan

    Jon Kirwan Guest

  17. Guest

    Apparently the first pictures from the surface of Mars were taken by
    Mars 3 in 1971, so successful landings happened a few years earlier.
  18. Guest

    It didn't take long before the A-12 became public knowledge. Revel even had
    accurate models of it, and the D-21 drone, within a couple of years. They did
    a much better job of covering up the B2 project.
  19. Same for the attitude thrusters on descent stage used to steer during
    the pre-parachute entry phase.
  20. Walter Banks

    Walter Banks Guest

    There was certainly lots of redundancy. One number that is still
    impressive was that with all of the redundancy NASA identified about
    250 remaining single point possible failures. The math on that many
    series terms makes the comment understandable.

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