What's the fastest speed a person has ever achieved?
Discussion
Definitely a Saturn V. Then escape velocity of the earth is roughly 25,000 mph (7 miles per second) This needs to be achieved to leave the earth and go into orbit around the sun. The Apollo astronauts who flew on top of the Saturn V had to achieve this speed to reach the moon. Techniccally, they went into a solar orbit which intercepted the moon's path. They were then "captured" by the moon's gravity and prevented from going into orbit around the sun.
To achieve earth orbit, you "only" need to get to 17,500 mph. So that is the target speed of a Shuttle (or Suyuz or any other earth orbiting manned spacecraft and low earth orbit satellite). Different speeds achieved will put you into bigger and bigger orbits around the earth, until you reach the magic 25,000 mph and you will break free of the earth's pull altogether.
To achieve earth orbit, you "only" need to get to 17,500 mph. So that is the target speed of a Shuttle (or Suyuz or any other earth orbiting manned spacecraft and low earth orbit satellite). Different speeds achieved will put you into bigger and bigger orbits around the earth, until you reach the magic 25,000 mph and you will break free of the earth's pull altogether.
dcw@pr said:
I've never understood the escape velocity thing. Is that 25,000mph in relation to the earth? I don't understand why you couldn't go 5,000mph for 5x as long, or 25mph for 1000x longer?
I have never considered it until now, but i think if you can imagine you were in a car with a bungee rope attached to a immovable object, you would accelerate up until the cord became tight, then you could speed up a little more and you could get a bit more stretch, but ultimately you will need the power to snap the bungee.If this is a half decent explanation i will be chuffed as i am a bit pished.
dcw@pr said:
I've never understood the escape velocity thing. Is that 25,000mph in relation to the earth? I don't understand why you couldn't go 5,000mph for 5x as long, or 25mph for 1000x longer?
First thing to remember is that once they've completed the rocket burn to break out of Earth orbit, spacecraft are just coasting without power - to maintain power would require stupendous quantities of fuel.So, if you were heading away from the earth at 5,000mph, without power you would just fall back to the Earth as the earths gravity is sufficient to reduce your velocity to zero. However if you're travelling at around 25,000mph, while the earth's gravity would still slow you down, you would have sufficient velocity that the earths gravity could never reduce it to zero ( remember the effect of gravity reduces by the square of the distance between the objects in question ). As it is, when the Apollo soacecraft went to the Moon, at the point where the Moons gravity becomes greater than the earths the spacecraft had slowed to only a couple of thousand mph - from which point on it speeded up again as it was being pulled by the Moon's gravity. Due to this effect the Apollo spacecraft didn't actually leave at full escape velocity - they didn't need to just to reach the moon.
To answer the OP's question, the fastest humans were the Apollo 10 astronauts returning from the moon - they hit the atmosphere at 11,107 m/s or 24,850mph
dcw@pr said:
I've never understood the escape velocity thing. Is that 25,000mph in relation to the earth? I don't understand why you couldn't go 5,000mph for 5x as long, or 25mph for 1000x longer?
The best demonstration of the principle I can think of is this.Imagine you are riding a bicycle, peddling furiously, and you are approaching a steep hill. As you approach the hill, on the flat, you peddle like mad and, just as the slope begins, you take your feet off the pedals and start to freewheel. Depending on how fast you had been travelling before you met the bottom of the hill, the further up the hill you will coast until you run out of momentum and start sliding back down the hill again.
If, theoretically speaking of course, you had been able to reach 25,000 mph by peddling REALLY hard, you could freewheel up the hill and, when you got to the top of the hill, instead of falling back down the other side, your momentum would carry you on up into the sky and evnnetually into an orbit around the sun.
In this example, of course, I am pretending that the earth has no atmosphere. Any object travelling at even a few thousand miles an hour in the earth's atmoshere will suffer tremendous frictional heating and at 25,000 would burn up completely.
However, this example would work on the moon. In fact, it is an entirely feasible method of launching objects off the moon or any similar airless body - not using a bicycle of course, but something like a mass accelerometer. Even better, the escape velocity of the moon is only about 4,500 mph (not 25,000 mph) because it is a much smaller body than the earth.
I am pretty sure that, once a moonbase is establshed, methods such as this will be used as a cheap way of launching vehicles off the lunar surface.
bobthemonkey said:
It was during the Apollo programme, specifically Apollo 10, on the return to Earth.
It was clocked at 24,830 MPH and is jointly held by Tom Stafford, John Young and Gene Cernan. (Depending on the body asks, Stafford is the record holder as he was the commander of the vehicle.)
That speed can't possibly have been safe. Ask any politician. It was clocked at 24,830 MPH and is jointly held by Tom Stafford, John Young and Gene Cernan. (Depending on the body asks, Stafford is the record holder as he was the commander of the vehicle.)
Eric Mc said:
dcw@pr said:
I've never understood the escape velocity thing. Is that 25,000mph in relation to the earth? I don't understand why you couldn't go 5,000mph for 5x as long, or 25mph for 1000x longer?
The best demonstration of the principle I can think of is this.Imagine you are riding a bicycle, peddling furiously, and you are approaching a steep hill. As you approach the hill, on the flat, you peddle like mad and, just as the slope begins, you take your feet off the pedals and start to freewheel. Depending on how fast you had been travelling before you met the bottom of the hill, the further up the hill you will coast until you run out of momentum and start sliding back down the hill again.
If, theoretically speaking of course, you had been able to reach 25,000 mph by peddling REALLY hard, you could freewheel up the hill and, when you got to the top of the hill, instead of falling back down the other side, your momentum would carry you on up into the sky and evnnetually into an orbit around the sun.
In this example, of course, I am pretending that the earth has no atmosphere. Any object travelling at even a few thousand miles an hour in the earth's atmoshere will suffer tremendous frictional heating and at 25,000 would burn up completely.
However, this example would work on the moon. In fact, it is an entirely feasible method of launching objects off the moon or any similar airless body - not using a bicycle of course, but something like a mass accelerometer. Even better, the escape velocity of the moon is only about 4,500 mph (not 25,000 mph) because it is a much smaller body than the earth.
I am pretty sure that, once a moonbase is establshed, methods such as this will be used as a cheap way of launching vehicles off the lunar surface.
Eric Mc said:
dcw@pr said:
I've never understood the escape velocity thing. Is that 25,000mph in relation to the earth? I don't understand why you couldn't go 5,000mph for 5x as long, or 25mph for 1000x longer?
The best demonstration of the principle I can think of is this.Imagine you are riding a bicycle, peddling furiously, and you are approaching a steep hill. As you approach the hill, on the flat, you peddle like mad and, just as the slope begins, you take your feet off the pedals and start to freewheel. Depending on how fast you had been travelling before you met the bottom of the hill, the further up the hill you will coast until you run out of momentum and start sliding back down the hill again.
If, theoretically speaking of course, you had been able to reach 25,000 mph by peddling REALLY hard, you could freewheel up the hill and, when you got to the top of the hill, instead of falling back down the other side, your momentum would carry you on up into the sky and evnnetually into an orbit around the sun.
In this example, of course, I am pretending that the earth has no atmosphere. Any object travelling at even a few thousand miles an hour in the earth's atmoshere will suffer tremendous frictional heating and at 25,000 would burn up completely.
However, this example would work on the moon. In fact, it is an entirely feasible method of launching objects off the moon or any similar airless body - not using a bicycle of course, but something like a mass accelerometer. Even better, the escape velocity of the moon is only about 4,500 mph (not 25,000 mph) because it is a much smaller body than the earth.
I am pretty sure that, once a moonbase is establshed, methods such as this will be used as a cheap way of launching vehicles off the lunar surface.
Traditionally, it's the only way - otherwise, rockets would be so large they couldn't even be launched.
Having said that, there is a form of continuous propulsion which has been tried and does actually work. It is known as Ion Drive and allows the spacecraft to push ions of a selected gas at a gentle rate out the back end. Accelleration is slow but continuous and can be applied over months - or even years - so, although the initial part of the journey is slow, over the months the speed builds up.
One moon probe called Smart 1 used this technique.
Here is a brief description of how an ion drive works -
Ion drive has a huge advantage over chemical rockets. A stream of xenon ions shoots away from the spacecraft at 10 times the speed of any rocket. So an ion drive spaceship can go 10 times as fast - or set off with one tenth of the fuel.
Smart-1 took 15 months to get into orbit around the moon (as opposed to 4 to 5 days for a traditional chemical rocket powered spacecraft). But over a much greater distance, the same technology will knock four years off a planned European voyage later in the decade to one of the solar system's most mysterious planet, Mercury
Having said that, there is a form of continuous propulsion which has been tried and does actually work. It is known as Ion Drive and allows the spacecraft to push ions of a selected gas at a gentle rate out the back end. Accelleration is slow but continuous and can be applied over months - or even years - so, although the initial part of the journey is slow, over the months the speed builds up.
One moon probe called Smart 1 used this technique.
Here is a brief description of how an ion drive works -
Ion drive has a huge advantage over chemical rockets. A stream of xenon ions shoots away from the spacecraft at 10 times the speed of any rocket. So an ion drive spaceship can go 10 times as fast - or set off with one tenth of the fuel.
Smart-1 took 15 months to get into orbit around the moon (as opposed to 4 to 5 days for a traditional chemical rocket powered spacecraft). But over a much greater distance, the same technology will knock four years off a planned European voyage later in the decade to one of the solar system's most mysterious planet, Mercury
Lefty Guns said:
pugwash4x4 said:
Solar sails have potential as well- just so long as we can get the material right- they certianly offer near lightspeed travel without excess energy requirements!
Really?!problem is that they are even slower to accelerate than ion drives.
The most realistic method of space travel is going to involve circumventing light altogether- bending the universe like a black hole!
Then advantage of ion drive is that the technology already exists and has been proven with a couple of test spacecraft. I fully expect ion drive spaceships to be the main way of getting about the solar system in the second half of the 20th century.
Solar sails are a great idea but there is still a lot of fundamental work that needs to be done on the materials that might be used in such systems. We might see workable solar sails by the end of the 21st century.
As for wormholes, stargates etc - they are really consigned to science fiction for the forseeable future.
Solar sails are a great idea but there is still a lot of fundamental work that needs to be done on the materials that might be used in such systems. We might see workable solar sails by the end of the 21st century.
As for wormholes, stargates etc - they are really consigned to science fiction for the forseeable future.
Gassing Station | Boats, Planes & Trains | Top of Page | What's New | My Stuff