In airports and shopping malls multiple, parallel moving "slidewalks" allow people to increase their velocity from a low speed to a high speed.


Consider the following image:

Multi-stage acceleration

The image shows a multi-stage acceleration trajectory. The idea is similar to people stepping onto ever-faster-moving parallel slidewalks. Instead of slidewalks, we use orbiting vessels. Instead of people, we use a transport shuttle (that carries people).

In the image, the orange concentric circles (1-4) represent the orbital stages of spacecraft traveling at different speeds, with an increase of speed proportional to its distance from Earth. The X's mark transfer points for the human-toting transport shuttle.

Each spacecraft in an orange orbit gains its velocity by swapping time for speed, such as an ion drive.

When the transport shuttle reaches stage 4 (or higher, if need be), it is at a sufficient velocity that a trip to Mars would only take a few weeks.


I am wondering:

  • Is this a viable acceleration technique to minimise human exposure to space?
  • What is this graduated acceleration technique called?
  • What are the disadvantages (cost, fuel, time, etc.) compared with current Mars visitation endeavours?



1 Answer 1


There's two ways to view your proposal;

If you can do impulse burns but not constant acceleration burns, like your mention of multi-stage accelerations suggests, then what you describe is a series of Hohmann transfers into higher orbital altitude, but instead of doing an orbital circularization burn, you continue with another apogee rising burn as the previous transfer reaches maximum altitude. This is not optimal as you don't take the most advantage of the Oberth effect and gradually increasing apogee with more energy efficient perigee burns, stretching into an ever more eccentric ellipse until you reach escape velocity.

But what you describe would work for non-impulse, constant acceleration propulsion, that is currently limited to low thrust but high specific impulse propulsion like ion thrusters, beamed propulsion, solar sails and alike.Those would be low energy transfer or constant thrust trajectories. But it's also often referred to simply as "orbit climbing".


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