Apollo missions

If the gravity on the moon is 6 times less it is on earth should have astonauts been able to jump six times as high as the could on earth ? or leap 6 times as far as they could on earth because their muscles are condition for a gravity 6 times as strong?

If the Apollo Astronauts had been wearing sports kit, and standing inside a large gymnasium on the Moon with a roof that was high enough, then yes, they could have jumped around six times as high, or as far, as normal. But they were wearing restrictive Apollo spacesuits and oxygen tanks, which more than doubled their effective weight, so they could only jump a little over twice their normal distance.

Neil Armstrong tried out the effect of low gravity by jumping from the Lunar surface to the third step of the lunar module ladder; a distance of five or six feet. He could manage this jump, despite the fact that the spacesuit knees were notoriously stiff, but he recommended that they didn’t do this again, and they didn’t.

“I did some fairly high jumps,” said Armstrong, “and found that there was a tendency to tip over backward on a high jump. One time I came close to falling and decided that was enough of that”

Another reason they didn’t try any of this is that falling and puncturing the suit on a rock would be a bad thing.

On Apollo 16 John Young and Charlie Duke had an impromptu “Lunar Olympics”, and Duke jumped high and landed… right on his backpack, and he was scared for his life because he thought he’d have damaged something structurally. He was OK, but it’s a good illustration that it pays to be cautious

Although on Apollo 14 Alan Shepard hit a golf ball and it went very far so yes, obviously lower gravity affects the motion of things

That’s also due to a lack of air resistance.

Actually, under normal Earthly conditions, a golf ball actually goes further than it would in a vacuum. The spin of the ball and the dimples manage to produce a small amount of lift as it moves through the air.

Would that be more than the drag that is imparted by generating that lift?

Mythbusters did that. They got golf balls without dimples and the dimpled ones went significantly farther. I don’t remember the numbers but I think it was around 30%. They also covered a car with clay, put scaled up dimples in the clay and got better gas mileage.

Yeah, but the non-dimpled ones were still subject to drag.

I doubt that they had the capability of testing a golf shot in a vacuum.

The question is, does the lift they get from their aerodynamics make up for the drag of passing through an atmosphere in the first place.

I don’t see how it could. Maybe if you hit it at a pretty low angle, then the lift will put it on a higher trajectory and keep it from landing sooner, and help it to clear obstacles. But, if two balls were fired at the same velocity, under the same gravity, both at 45 degrees to the horizon, I don’t see how the one subject to air resistance could possibly go further.

It’s hard to hit golf balls in a vacuum, but it’s easy to measure a golf ball’s initial velocity, and to calculate from that how far it would go, in a vacuum.

Okay, and that explains that dimpled balls go further than smooth balls, mostly by reducing drag and partially by creating lift.

Does not say anything about how they would fare in a vacuum. Dimpling the ball reduces drag by half, having no air resistance at all would decrease even further.

And has this been done?

So, a tiny bit of research. No, that I can find, no one has done this experiment.

However, serious golfers do take atmospheric conditions into account. Temperature, humidity, and altitude, so the question is actually pretty well answered.

So, yes, air resistance does decrease the distance, so a golf ball in vacuum would travel further.

I’ve always wondered just how much thrust it would take to put an astronaut in an EVA suit into lunar orbit. Could a spring-loaded catapult do it? Assuming their command module had the maneuvering abilities for the rendezvous, could the next people on the moon forgo the need for an ascent stage?

You are still pushing nearly 4000 mph to orbit the Moon.

Be one hell of a catapult, and you’re not going to survive.

OTOH, using a maglev type of accelerator track would be much more viable. You don’t have to provide the vacuum, it’s already there. You can accelerate up to the necessary speed and then basically just drift off.

I think it was Clarke who noted one of the significant dangers of being on the moon: if you are on the edge of a 200’ cliff, you might be lulled by the low gravity into thinking you could just jump safely to the plain below, but it would actually be like falling nearly forty feet (no wind resistance), which can easily be fatal. And there is no way to change your position on the way down, so if you start off with a tumble, that is how you will land.

Once that catapult, or the launch track, has done its work, the payload (in this case, an astronaut) enters an elliptical orbit which will bring him back to the same position and velocity. The moon will have rotated just a bit, so he won’t collide with the catapult. Unless your launch trajectory is perfectly horizontal, chances are that elliptical path is going to intersect the moon.

You need some way of altering your trajectory (a rocket pack of some sort) after launch, or you will come back to where you started.

Another take on dimpling…this Lexus commercial.

That’s one of my Unca Walt memories. After Shepherd hit the ball, CBS’ color man (Slayton?) commented, “Yanno, with no air, the ball couldn’t hook or slice – it’s guaranteed to fly straight.”

Cronkite replied, “I’d bet I’d make it slice.”

True, you need some additional thrust after the catapult, to put you into an orbit that doesn’t intersect the surface. But it wouldn’t need to be very much additional thrust, with no atmosphere to deal with.

And in case anyone’s wondering, on Mars’ smaller moon Deimos, an Olympic athlete in a sufficiently non-restrictive suit could probably jump into orbit.