How to get an obect to stop rising?

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Discussion Overview

The discussion revolves around the mechanics of launching a rocket, transitioning from vertical ascent to achieving orbit, and the subsequent navigation to celestial bodies such as the Moon or Jupiter. It covers theoretical and practical aspects of rocketry, orbital mechanics, and interplanetary travel.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants suggest that to stop a rocket's vertical ascent and start it into orbit, it is essential to gain horizontal velocity rather than just altitude.
  • One participant notes that a satellite must reach a speed of approximately 16,000 mph to maintain orbit.
  • Questions arise about the mechanisms used for changing a rocket's trajectory, with mentions of thrusters, fins, and thrust vectoring nozzles.
  • It is stated that once in orbit, maintaining that orbit requires very little energy due to negligible friction, although compensatory burns may be necessary for orbital decay.
  • Participants discuss the complexities of interplanetary travel, indicating that it involves achieving escape velocity and timing engine burns for trajectory corrections.
  • There is mention of different strategies for interplanetary journeys, including optimizing for time or fuel and utilizing gravity assists from other planets.

Areas of Agreement / Disagreement

Participants generally agree on the need for horizontal velocity to achieve orbit and the low energy requirement to maintain orbit. However, there are varying perspectives on the specifics of trajectory adjustments and the methods used in rocketry, indicating that the discussion remains unresolved in some areas.

Contextual Notes

Some assumptions about the mechanics of rocket propulsion and orbital dynamics are not fully explored, and the discussion does not resolve the complexities of interplanetary navigation.

jehan60188
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once a rocket is launched vertically, how does one stop it's rising, and start it into an orbit around earth?
actually, the only thing I can really fathom is launching a rocket straight up, and having it fall back to earth, or having it leave Earth's gravity, and drift off into whatever trajectory the universe selects for it
so, how about getting it to the moon, or steering a probe to jupiter?
thanks!
 
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jehan60188 said:
once a rocket is launched vertically, how does one stop it's rising, and start it into an orbit around earth?
It takes very little of a rocket's energy to get it from 0 alt to 100 miles. The vast majority of the energy is put, not into altitude, but into horizontal velocity. A satellite needs to be moving at 16,000 mph to achieve and remain in orbit.

When you watch rockets lift off, you will see them go straight up only for a very short period, they almost immediately tilt and gain speed over ground. That's the key to orbit.
 
how does that happen? thrusters? fins?

once an object is in orbit, it's my understanding that it takes very little energy to keep it there (since there's negligible friction). is that an inaccurate statement?

what about getting to the moon or jupiter? is it just another degree of tilting?
 
jehan60188 said:
how does that happen? thrusters? fins?
Thrust vectoring nozzles: The nozzles move.
once an object is in orbit, it's my understanding that it takes very little energy to keep it there (since there's negligible friction). is that an inaccurate statement?
It is accurate.
what about getting to the moon or jupiter? is it just another degree of tilting?
And additional speed, yes.
 
jehan60188 said:
how does that happen? thrusters? fins?
Yes and/or yes. Fins rapidly become useless so usually it's a matter of angling the main propulsion.

jehan60188 said:
once an object is in orbit, it's my understanding that it takes very little energy to keep it there (since there's negligible friction). is that an inaccurate statement?
It is an accurate statement. Except for the occasional compensatory burn for orbital decay due to atmo friction, it takes zero energy to keep in orbit.

jehan60188 said:
what about getting to the moon or jupiter? is it just another degree of tilting?
An interplanetary journey is about firing up your engines to achieve escape velocity - your orbit spirals outward. You must time your burns and do corrections so that you hit your next target, which might be a gravity-assist from another planet. Depending on whether you want to optimize time or fuel, you choose different journeys. Some journeys can visit more than one planet, or even the same planet on several successive passes before ending upon a final path to your destination.
 

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