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4

For birds, NASA deployed its heavy weaponry - propane cannons. A series of 25 liquid propane cannons, placed in strategic locations along the east and west sides of the SLF runway, are controlled by air traffic controllers in the tower and remotely by bird-watchers in the field. These cannons, installed in September 2007, are fired randomly by ...

2

Firstly, the bumping appears more dramatic because of the lower gravity. An object bumping on Mars will go 2.6 times higher on Mars than something with the same velocity on Earth. Secondly, the bumping is both desirable and unavoidable. When landing or Mars, a rover would always have some velocity, as parachutes are limited by the thin atmosphere, and ...

8

You're talking about the Mars Exploration Rovers. They landed using airbags. To do what you suggest, they'd have to vent the airbags with great precision at the moment it hits the ground. If the timing's just a little bit off, the airbag would collapse and the rover inside would hit the ground hard, or it wouldn't collapse enough and bounce anyway. It's ...

1

There is a way to land on the moon using less energy than it requires to reach Lunar orbit. It requires a megastructure, but one that we have the materials to build today. https://www.technologyreview.com/s/614276/a-space-elevator-is-possible-with-todays-technology-researchers-say-we-just-need-to-dangle/ Just dangle a rope down from the moon to (roughly) ...

6

Yes, this can be done by using a circular magnetic track, like for a maglev train. A spacecraft should approach with low vertical and high horizontal velocity, landing on the short straight section like an aircraft on the runway. This part could be shaped like a funnel, allowing some imperfections of the landing approach. The "magnetic runway" should then ...

6

I'm going to take a different approach here, which only makes sense in the context of repeated landings after we already have people or robot-like things up there. Create a large lattice of materials on the Moon, then fire the lander at the lattice. This is effectively like giving the Moon a localized atmosphere and using drag to slow the lander down. The ...

5

One option might be a penetrator -- a hard dart-shaped vehicle designed to hit the ground point first at 2.4 km/s and come to a stop in a few meters of regolith. The deceleration would still be severe but specialist electronics could be expected to survive it. The speed of sound issues mentioned above would be alleviated because the penetrator is made of ...

4

I think you could do it with a rotating skyhook The skyhook would be in a low lunar orbit, and the payload would catch the upper end at about escape velocity, or twice orbital speed. It's then swung down and backwards until it's almost stationary and released. The tallest mountain on the moon is about 5km, so potentially it would have to withstand a 5km ...

3

Some of the Ranger probes (including Ranger 3) to the moon had balsa-wood landers. Unfortunately, none of the ones that were working when they reached the moon carried them. So we believe it's possible. It just comes down to how much crumple-zone you can afford to carry and how much impact you can stand.

43

It is not practical to use this approach from orbital (1.6km/s) or escape velocity (2.4km/s), for two major reasons. The first is the acceleration reason. The kinematic for bringing objects to a stop under constant acceleration is $$d = \frac{v^2}{2a}$$ from which we can quickly solve for the acceleration to be $$a = \frac{v^2}{2d}$$ Even with 10 meters of ...

10

Well, lunar escape velocity is 2.38 km/s. So this is about the speed that a rover dropped in from orbit (with no sideways velocity) will hit at. So let's take a guess at how many g's deceleration will be. Assume it has 10 meters of crumple to stop in. It will take it about 10/2380 seconds to stop. Which is .0042 seconds. Deceleration will be 2380 / .00042 = ...

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