19 thoughts on “Elon’s Telecon”

  1. This part has me scratching my head:

    Cause of abort?
    – Problem with igniter on engine 3
    – Sensors measure pressure as too high.
    – After examination, decided limits were too conservative and widened them.

    Why the quick decision to think the limits were too conservative? Why have abort criteria, if you then override them so quickly?

    This sounds either a little too “cowboy-ish” or a little too convenient. Don’t get me wrong, I’m a huge SpaceX fan and am very happy to see this success, but I’d like to know what went into the risk analysis to so readily change the criteria.

    It’s an old flying axiom that you make critical abort decisions at 1 g and zero knots so you don’t have to make them in the heat of the moment. I realize the analogy isn’t perfect (the abort did happen after all) but what they did is akin to taxiing around and taking off again anyway.

    A little voice, that I don’t want to believe, is telling me that a possibility is that the criteria was known to be too conservative prior and therefore this was an “anticipated” shutdown that then demonstrated the rapid turn-around capability (that was actually very impressive.)

    Just a thought. All of you “real” rocket scientists out there may have a much better explanation.

  2. Total SpaceX expenditures?
    – The $350M-$400M mentioned the other day was for Falcon 1 and Falcon 9 rockets.
    – Dragon, facilities, pad, etc add up to about another $100M-$150M.
    – So total SpaceX expenditures till now adds up to around half a billion dollars.

    Thank you, Elon. You just set a benchmark for the space investment capital. And at the same time, you made state-sponsored welfare programs look really bad.

  3. Why the quick decision to think the limits were too conservative? Why have abort criteria, if you then override them so quickly?

    There are lots of overly conservative models that add worst on worst uncertainties in the desire for an abundance of caution. Every now and then, it makes sense to realize you have excessive conservatism that needs to be dialed back. What would be really bad is not having conservatism to back out.

  4. Realize that this is just one abort criteria of many. Also, it occurred on just one engine of nine. Also, measurement in the real world are never exact, they are always in a range. Last also, this is a first flight. You want your criteria as tight as possible. Since only one of nine engines went passed the point they did a fine job. An amazing job really. This is why I predict launch on Saturday. They were better than I even expected.

  5. The details about the Dragon capsule LAS is very interesting. They even mention the potential of using the LAS as soft landing rockets for land recovery.

    But considering the ultimate ambition of SpaceX is Mars, I wonder if the Dragon capsule might even one day evolve into a Mars lander. A Dragon Mars-lander may not be useful for crew, but it could serve missions for unmanned cargo delivery or robotic exploration.

  6. Alan Boyle had a collection of comments on the flight, positive and negative. http://cosmiclog.msnbc.msn.com/_news/2010/06/04/4465072-spacex-fans-and-foes-speak-out

    The negative ones are simply astonishing, especially Richard Shelby’s “As a nation, we cannot place our future spaceflight on one fledgling company’s definition of success.”

    One company’s *definition* of success? Does Shelby confuse fact with definition? Of course, the arguments on the electric car thread (below) show that anything is possible.

  7. while the Apollo lunar lander weighed approximately 10 metric tons, a human mission to Mars will require three to six times that mass, given the restraints of staying on the planet for a year

    Still reading, but here’s the first false statement. This seems to assume a single large lander. Supplies should arrive first with as many landings as needed. They should be oversupplied.

    Landing people does require a larger lander…

    There’s too much atmosphere on Mars to land heavy vehicles like we do on the moon, using propulsive technology completely

    Blatantly false. We don’t currently have a vehicle, but that doesn’t mean we can’t come up with one. We use earths atmosphere to help us land here, but can’t do the same on mars. We just need to slow the vehicle before atmospheric friction on mars heats it too much. Perhaps with a staged descent. SRBs, jettisoned before landing, might be used.

    Parachutes can only be opened at speeds less than Mach 2, and a heavy spacecraft on Mars would never go that slow by using just a heat shield.

    Ok. They reached the same conclusion as I, but don’t realize it.

    but the problem is that right now the heat shield diameter for a human-capable spacecraft overwhelms any possibility of launching that vehicle from Earth

    Even an inflatable?

    Therefore using propulsive technology alone is not an option

    Only because they assume waiting until the atmosphere is thick enough to cause a problem. You use rockets before it becomes an atmospheric problem and jettison them so the vehicle has a much different landing profile than what they assume.

    Now we come to hypercones… I now have a name for my suggestion above.

    Finally they come to space elevators which does seem to make sense on mars, but not here on earth IMHO. It doesn’t address the near term issue.

  8. Ken, I recommend the formal paper (the first pdf link) by Robert Manning. Manning does discuss inflatables, etc, but also points out that the current state of the art for landing on Mars has a limit between 1 and 2 metric tons while Drgon is roughly 8 metric tons.

  9. Sorry – Manning doesn’t point out anything about Dragon — that’s just my response to Brad. Anyway, this is all quite premature. SpaceX has enough to worry about for the future — once they get done celebrating, that is!

  10. Bob-1

    As long as you are getting into the weeds, we might as well delve for greater accuracy.

    According to the most recent and most detailed information I have seen from Flight Global, the current Dragon capsule does not mass 8,000 kg. (What a speculative Mars-lander might mass is obviously pure guesswork).

    The dry mass of the Dragon capsule, minus it’s trunk which it jettisons before re-entry, is only 2,500 kg. (Maximum gross, and with the trunk, is only 7,000 kg.) So the mass difference between the Dragon and current Mars Landers is much less than you implied.

    Nor must we assume SpaceX will necessarily try to beat every problem outlined in the EDL paper. For example, there are plenty of interesting low altitude locations on Mars.

  11. I don’t see dragon being modified as a mars lander at all. It has quite enough to do getting to and from earth orbit. Unless you count dragonlab with it’s on orbit duties.

    The mars lander is going to need a fresh approach.

  12. Not to mention that a one size fits all craft is a guaranteed failure. I think Rand, Jon and others have written on this a number of times.

  13. Ah, the lack of imagination in the Mars lander paper is stunning. The paper assumes that the size of the aeroshell is limited to the diameter of the launch vehicle.

    That’s just an arbitrary limit. Simply assemble a hard aeroshell in Earth Orbit of the size that is needed.

    Furthermore, there is a strong assumption that a lander mission needs to come in one piece … that’s also kind of stupid and self limiting.

    I get the point of the paper; Mars’ atmosphere is quite thin, thus resulting in very little time/distance post re-entry.

    A Hypersonic lifter would be very helpful, allowing the use of lift to increase both time and distance prior to final touchdown.

    Even the paper acknowledges that an all rocket descent is possible, just expensive in terms of propellant. Which is a problem that can be ameliorated with depots and ISRU

  14. I don’t know how anyone could get the idea I was proposing a “one size fits all craft”.

    Picky picky picky!

  15. bob-1

    Re-entry mass of a Dragon capsule could vary a great deal, because of the large downmass capacity of the capsule.

    Anyway, here is all the best info I have on Dragon capsule specifications. I don’t have the link for the Flight Global article I took the info from, so you will have to google that article yourself.

    source — Flight Global

    Dry mass — 3,180 kg (7,000 lbs)

    Wet mass — 4,540 kg

    Max gross — 7,000 kg

    Max payload — 2,500 kg

    Prop — 1,227 kg total = NO4 + MMH

    Service module takes up bottom 1.3 m of capsule

    Capsule made of composite material

    15 degree sidewall angle

    Trunk mass — 681 kg

    Capsule maximum base diameter — 3.81 m (12.5 ft)

    Falcon 9 LEO payload — 8,700 kg

  16. Contemplating the Dragon stats, it occurs to me that if those stats are accurate, then SpaceX has achieved a remarkably light vehicle for it’s class.

    The vehicle most directly comparable in pressurized volume would be the Soyuz, yet the dry mass of the Dragon is roughly half that of the Soyuz! Perhaps it’s the composite material construction that permits such an improvement?

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