Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: pharmacist2030 on 12/08/2012 14:18:38

Title: Is there a certain trajectory that launching spacecraft should follow?
Post by: pharmacist2030 on 12/08/2012 14:18:38
Is there a certain pathway that spaceships should pass through before reaching the space?
Title: Re: Spaceships
Post by: CliffordK on 12/08/2012 20:50:08
Are you meaning "rockets"?  or "spaceships"?

Obviously the shuttle was the largest of the "spaceships" that we have made to date.  Anything larger would likely be built on Earth (or on the moon), in pieces, then and assembled and fueled in pieces in space. 

The key to our current rocketry is that "energy is expensive", so a lot is done to minimize the energy expenditure.

Most of the rocket launches are initiated near the equator, and launched eastward to utilize the intrinsic motion of the earth.  However, "polar orbits" would be launched northward or southward. 

Where one would assemble a spaceship in space would be up to the team.  The international space station was launched into a low earth orbit which is easiest to get to from Earth. 

The Earth/Moon L1 Lagrangian point ( would be a logical place for a space station and collaboration efforts between future Earth and lunar colonies. 

If you look at the Lagrangian gravity contours, it might suggest launch pathways.


If one needs to alter the direction of travel, then a slingshot around the moon may help save energy.  The launch may also involve several orbits around the earth.

Here is a diagram of the STEREO satellite launch. (  The "stereo ahead" and "stereo behind" satellites used slightly different paths and lunar encounters to end up going in opposite directions around the sun.

Title: Re: Spaceships
Post by: wolfekeeper on 13/08/2012 01:16:36
To get to space, a rocket just needs to go straight up.

But you may be thinking about when a rocket launches into orbit.

In that case, there's a particular path (more properly referred to as 'trajectory') that gets the vehicle into orbit using the minimum amount of fuel, which allows the vehicle to carry the biggest possible payload.

The typical trajectory starts at the surface of the Earth and goes off at an angle close to vertical and progressively leans over between 30-40km and eventually goes horizontal until it reaches orbital speed at the target altitude (which is usually above 160km).

This trajectory avoids going too fast through the thick bits of the air, and this saves fuel, although it costs more fuel because the vehicle has to go more slowly initially,so the vehicle has to hold itself up on rocket fuel for longer before it reaches orbit, so it's a careful trade-off.