# Could you send an object into space completely without fuel?

• rumborak
In summary, this project used two 16" naval guns to shoot small projectiles into space to study re-entry effects. The project was shut down after it was discovered that one of the guns was used to assassinate a scientist who had sold his technology to Saddam Hussein.
rumborak
Was pondering this today. Obviously you wouldn't be able to accelerate a 1-ton satellite to escape velocity, but what about small objects? 11km/s (well, even more, to overcome friction on the way) is very daunting, but if it could be managed you could easily send large amounts into space. And without the "a single mistake wrecks millions of dollars" to boot.

EDIT: A quick v^2 = 2as says that if you could accelerate at 10g for 55m, you would reach escape velocity. That doesn't sound too bad.

Last edited:
Astronomy news on Phys.org
rumborak said:
Was pondering this today. Obviously you wouldn't be able to accelerate a 1-ton satellite to escape velocity, but what about small objects? 11km/s (well, even more, to overcome friction on the way) is very daunting, but if it could be managed you could easily send large amounts into space. And without the "a single mistake wrecks millions of dollars" to boot.
Been there, done that:

http://en.wikipedia.org/wiki/Project_HARP

This project used a couple of 16" naval rifles joined back to back to try to fire small projectiles into space to study re-entry effects on these projectiles. The rifles were located in Barbados and made a number of test firings before the program was shut down. Although no longer used, at least one of the rifles is still on the island.

Wow, the guy who did those experiments was one hell of a sketchy dude.

Had a quick look, quite a story - complete with assassination by secret agents after selling his technology to Saddam Hussein, when does the movie come out ?; )

Keep in mind that, when you lob that unpowered payload into space, you'd better have something up there to catch it, or it's going to come right back down.

A ballistic path is the same as an elliptical path and, unless you give it a boost, you cannot actually get it into an orbit that does not intersect the Earth.

That's an interesting point, I didn't consider that. But, I would hazard a guess that the majority of a rocket's propellant is spent on overcoming gravity, and that the acceleration to get it from an elliptical to a circular orbit would require much less propellant.

rumborak said:
That's an interesting point, I didn't consider that. But, I would hazard a guess that the majority of a rocket's propellant is spent on overcoming gravity, and that the acceleration to get it from an elliptical to a circular orbit would require much less propellant.
Actually, the majority of propellant is spent gaining speed. Climbing to 200 miles altitude is a pittance compared to accelerating to 18,000mph.

Well, that scratches that idea then! :D

Not entirely. Firing a cargo to orbital speed will certainly save you a huge amount of fuel. You are right that it wouldn't take too much to alter its ballistic trajectory into a stable orbit.

Is it possible to shoot such artilerry guns from an airplane?
If it was, people could take the gun to a very high altitude and shoot it with some angle, not quite vertical, so that it has some angular velocity too which makes it possible to have a closed orbit.

wabbit said:
Had a quick look, quite a story - complete with assassination by secret agents after selling his technology to Saddam Hussein, when does the movie come out ?; )

No movie, but it did inspire the novel "The Fist of God" by Frederick Forsyth.

DaveC426913 said:
Actually, the majority of propellant is spent gaining speed. Climbing to 200 miles altitude is a pittance compared to accelerating to 18,000mph.

This is why anti-satellite weapons are launched from zoom-climbing fighter aircraft instead of the ground but we don't bother with aircraft boost for satellite launches. Anti-satellite weapons just need to get up there long enough to destroy their target, but satellites have to get up there and stay there.

Shyan said:
Is it possible to shoot such artilerry guns from an airplane?
If it was, people could take the gun to a very high altitude and shoot it with some angle, not quite vertical, so that it has some angular velocity too which makes it possible to have a closed orbit.
In a word, No, it would not be possible to carry one of these guns aloft and fire it, let alone two joined in tandem.

Just one 16" naval gun weighs more than 100 long tons (100,000 kg) and is approximately 20 meters long. This photo gives an indication of how massive one of these guns is:

Project HARP used two of these monsters in tandem. Should you even get such a massive assembly aloft, firing it from an aircraft would be interesting, to say the least.

SteamKing said:
Should you even get such a massive assembly aloft, firing it from an aircraft would be interesting, to say the least.
It would shortly stop flying. And then shortly thereafter stop being an aircraft.

Shyan said:
Is it possible to shoot such artilerry guns from an airplane?
If it was, people could take the gun to a very high altitude and shoot it with some angle, not quite vertical, so that it has some angular velocity too which makes it possible to have a closed orbit.

Putting aside the problems with getting such a gun on a plane and firing it. This would not have the effect you desire. Any "orbit" the shell enters after leaving the gun will return it to the point where it was fired. You would have an orbit that would keep dipping back into the atmosphere back to the altitude from which it was fired. Passing through the atmosphere will cause it to lose speed with each pass, causing the upper part of the orbit to lower down into the atmosphere over time, which will result with it falling out of the sky.

Secondly, firing it at any angle other than parallel to the ground just makes matters worse. The shell will still return ( or try to return) to the firing point, but now the lowest part of the orbit will be closer to the Earth than the firing point and it will spend even a longer time in the atmosphere. As you increase the angle towards vertical you get to a point where the trajectory will intersect the surface of the Earth before it returns to the firing point.

jackwhirl said:
The whole list is quite interesting, though your feasibility may vary: http://en.wikipedia.org/wiki/Non-rocket_spacelaunch
I wonder how these options would compete, on a cost basis, with conventional rockets once SpaceX figures out how to land and recycle its boosters.

Recently, the US Navy has been performing trials on a prototype electromagnetic rail gun:

http://en.wikipedia.org/wiki/Railgun

The test gun has been shown to throw a projectile at a velocity of 2400 m/s. Eventually, the Navy hopes to develop a gun capable of accelerating a projectile to 7000 m/s.

At the equator, the Earth's rotational speed is about 465 m/s. Orbital speed at the same location is 7900 m/s relative to a fixed reference. A rail gun capable of orbiting a payload would need to be capable of imparting a Δv of about 7500 m/s, in round numbers.

http://en.wikipedia.org/wiki/Orbital_speed

Here is a pic of the USN rail gun test:

The flames are from the atmospheric heating taking place after the projectile has reached a velocity of 2400 m/s​

rumborak said:
EDIT: A quick v^2 = 2as says that if you could accelerate at 10g for 55m, you would reach escape velocity. That doesn't sound too bad.
sqrt(2*100m/s^2*55m)=105 m/s. You need a factor of 100 more speed, or a factor 10000 more energy. 1000g at 5.5 km would work.

HARP only reached 3.6 km/s. Guns give massive accelerations, but reaching a high speed is difficult - exceeding the speed of sound with that concept is hard to impossible, and even light gases like hydrogen or helium have to be very hot to get a sound velocity in the range of 10 km/s. See also light gas gun.

This concept is entirely possible, if the atmosphere didn't get in your way to stop your projectile from reaching space without completely disintegrating. If the atmosphere were magically removed, yes the objects you launch can certainly get into space. As everyone said before, it wouldn't complete an orbit as it would want to return to the same spot it was launched at.

## 1. How is it possible to send an object into space without using any fuel?

It is not possible to send an object into space without using any fuel. Fuel is necessary to provide the thrust needed to overcome Earth's gravity and the atmosphere's drag.

## 2. Can solar power be used as an alternative to fuel for sending an object into space?

Solar power can be used to power spacecraft and satellites once they are in space, but it cannot be used as a means of propulsion to launch them into space.

## 3. Is it possible to use other forms of energy, such as nuclear power, to send an object into space?

While nuclear power has been used in the past to power spacecraft, it still requires some form of fuel for the initial launch into space. Additionally, the use of nuclear power for space launches presents significant safety and environmental concerns.

## 4. Are there any proposed technologies or concepts that could potentially allow for space travel without using fuel?

There are some proposed technologies, such as solar sails and electromagnetic propulsion, that could potentially allow for space travel without using fuel. However, these are still in the early stages of development and have not been proven to be viable methods of propulsion.

## 5. What are the limitations of using fuel to send objects into space?

Using fuel for space launches can be expensive, and the amount of fuel needed increases dramatically with the weight of the object being launched. Additionally, the use of traditional rocket fuel can have negative impacts on the environment, making it important to explore alternative methods of propulsion.

Replies
19
Views
3K
Replies
30
Views
4K
Replies
3
Views
2K
Replies
5
Views
1K
Replies
4
Views
7K
Replies
5
Views
8K
Replies
2
Views
7K
Replies
1
Views
3K
Replies
5
Views
4K
Replies
0
Views
1K