[slacka]

Could and real or kerbal rocket scientists here explain why SpaceX isn't doing something like the curiosity rover landing? Sure there's 3 extra steps, deploy parachute, cut parachute, and evasive maneuver, but the fuel saving would massive.

[JshWright]

I'm not sure the savings would be as massive as you think (and would be offset by other costs).

Parachutes (and associated equipment) are heavy, so you'll burn fuel lifting that extra weight.

Parachutes are complicated, and would be an extra system to develop, test, and validate.

Parachutes are annoying to repack/replace (increasing turnaround time).

Parachutes put odd stresses on large objects when they deploy (increasing the amount of inspection you would have to do after each flight).

All that hassle to reduce the terminal velocity by a couple hundred miles an hour. That's not that big a win for a pretty high cost.

[Florin_Andrei]

> All that hassle to reduce the terminal velocity by a couple hundred miles an hour.

That's the TLDR. The delta-vee from the parachute is not worth the trouble.

[mikeash]

Or put it another way, parachutes are generally less effective than using a system you already have for other purposes. A parachute probably beats a rocket engine if your only task is landing, but when you already have the rocket engine, you're better off using it for landing than building a completely separate landing system.

In short, same basic reason why we use wings and wheels to land airplanes rather than dropping them from a parachute when they reach their destination.

[schiffern]

Not "massive". The empty stage is very light, so a little propellant goes a long way. It's less than 10% of the fuel for the entire descent phase (and the optimal upper stage length goes up to compensate somewhat).

[smackfu]

Well, one reason is that parachutes at this scale aren't that simple. For instance, check out the ones on the Shuttle SRBs: http://en.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_Boos...