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Comment by grecy | Hacker News Reader

I keep hearing lots of great ideas about how something other than the rocket could help the rocket land (catch it, move the platform, use a net, etc. etc.)

I honestly think SpaceX have no intention of learning how to do any of those (even though some might work great) because they want to learn how to land it in a place with no "smart" landing pad already setup.

i.e. Mars

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Yes. That is also the reason they will not try to move the barge in unison with the rocket even if that was possible. Barge is trying to representing land.

The maneuver made by the rocket to land at an angle is intentional. The rocket wasn't trying to correct some unknown balance issue with it. The reason for too fast sideways speed came from the problem with the rockets response time, signal->engine.

The big sideways maneuver is made so the rocket will not hit the barge at high speeds in case of any problems.

Wellll, it's going to be a lot sooner than Mars. They inked a contract recently with the USAF to use a pad for landing. I don't know when that's supposed to happen, but the barge was never more than a stopgap until they could secure a spot on land and work out all the regulatory concerns.

> Wellll, it's going to be a lot sooner than Mars

For sure, but even then they could use some kind of tower or arm on their earth-based landing pad to "catch" it if they wanted. In theory they could even have the pad move some amount.....

If they wanted to of course, which they don't.

I would be shocked if any of that was actually easier than getting the landing right. Vertical landing without special arms or pads has been done a dozen times by now - DC-X, Armadillo, JAXA's RTV, Project Morpheus, and especially SpaceX's F9R... that's just off the top of my head.

The part that hadn't been done is getting from a fast, high altitude trajectory to the landing spot. Which they've managed to do.

Can a Falcon Heavy get the full center core of the rocket, including the first stage into orbit? Maybe with no payload? If so, this would mean transporting and landing a stage on Mars, for use as a return launcher, would be possible. Is this a possible long term plan?

I expect the more difficult part is getting the necessary fuel to Mars to escape. Obviously you could do it if you took enough trips, but that would likely be prohibitively expensive.

the plan that makes most sense is to produce fuel on site. allegedly there's water below Mars surface, so LOX/LH should be doable. maybe there's more stuff to synthesize methane, RP-1 or other fuels.

One plan I've seen for ISRU on the moon is to use a Al-Lox hybrid engine, since Al2O3 is all over the moon's surface. I wonder if there's enough on Mars to do the same thing, or if you could do something with iron oxide.

Definitely not. A fully fueled F9 first stage is about 500 tonnes, and can lift 13 tonnes to LEO; a Falcon Heavy is three first stages duct-taped together, and all three working together can only lift 53 tonnes.

> a Falcon Heavy is three first stages duct-taped together

I bet they didn't buy that cheap duct tape that stops sticking after 5 minutes :)

Odd that you say that --- that's about when the two booster stages are supposed to be dropped...

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