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emma149
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how do space ships come to rest when they get into space?
Landing a Spacecraft: Understanding Gravity in Space
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In summary, space ships come to rest by using gravity assists to slow down, then firing their retro rockets to achieve an elliptical orbit around the destination body.
- #2
Vagn
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emma149 said:
Rest with respect to what?
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Nik_2213
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Are you thinking of geo-stationary orbits ? Or 'entering' the L4/L5 halo positions ? Taking up Mercury or Mars orbit ??
To 'get there', you need relative velocity, then you must shed that excess velocity with Retro-rockets or whatever you want to call the payload's final propulsion system. To minimise fuel use, spacecraft may use gravity assists, a diminishing succession of elliptical orbits with sparing thrust at critical time, ion thruster or aero-braking...
A really careful trajectory that uses planetary gravity to sling-shot probes can easily double or treble the available payload...
To 'get there', you need relative velocity, then you must shed that excess velocity with Retro-rockets or whatever you want to call the payload's final propulsion system. To minimise fuel use, spacecraft may use gravity assists, a diminishing succession of elliptical orbits with sparing thrust at critical time, ion thruster or aero-braking...
A really careful trajectory that uses planetary gravity to sling-shot probes can easily double or treble the available payload...
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Filip Larsen
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emma149 said:
The short answer is that they don't really come to rest when in space. Like roller coasters without brakes they are (by intention of the designers) always moving (actually, free falling) with fairly great speed "around" the body they orbit so that they won't "fall into" the body.
In case you are thinking of geo-stationary satellites, as Nik mentions, you should know that such satellites are in fact orbiting the Earth, they just do so at exactly the same rate as the Earth rotates, so when you view one from the surface of Earth the satellite appears to just hang there (see [1]). Its like a child sitting on a merry-go-round watching her (fairly athletic) dad running along on the ground just outside with his video camera keeping up with the rotation of the merry-go-round; the man is not moving relative to the view of his child even though he is running like mad over the ground.
[1] http://en.wikipedia.org/wiki/Geostationary_orbit
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emma149
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with respect to the moon.
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tiny-tim
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welcome to pf!
hi emma! welcome to pf!
the usually fire their rockets "backwards" on the way to the Moon, to reduce their speed relative to the Moon, and then again on the other side of the Moon, to make the orbit circular
see eg http://en.wikipedia.org/wiki/Apollo_8#Lunar_sphere_of_influence"
hi emma! welcome to pf!
emma149 said:
the usually fire their rockets "backwards" on the way to the Moon, to reduce their speed relative to the Moon, and then again on the other side of the Moon, to make the orbit circular
see eg http://en.wikipedia.org/wiki/Apollo_8#Lunar_sphere_of_influence"
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FAQ: Landing a Spacecraft: Understanding Gravity in Space
1. How does gravity affect a spacecraft during landing?
Gravity plays a crucial role in the landing of a spacecraft. As the spacecraft approaches a planet or moon, the gravitational force of that celestial body pulls the spacecraft towards it. This force must be countered by the propulsion system of the spacecraft to slow it down and ensure a safe landing.
2. Why is it important to understand gravity in space when landing a spacecraft?
Understanding the effects of gravity in space is crucial for successful spacecraft landings. Gravity affects the trajectory, speed, and force of the spacecraft during descent, and failure to account for these factors can result in a crash landing or missed target. By understanding gravity, scientists and engineers can accurately calculate and adjust the spacecraft's trajectory to ensure a safe landing.
3. How does the gravity of different celestial bodies vary and impact spacecraft landing?
The strength of gravity varies among different celestial bodies, depending on their mass and size. For example, the gravity on the moon is much weaker than that of Earth, while the gravity on Jupiter is much stronger. This variation can impact the speed and trajectory of a spacecraft during landing, and engineers must take this into account when planning a landing mission.
4. What are some challenges of landing a spacecraft in a low-gravity environment?
Landing a spacecraft in a low-gravity environment, such as on the moon or an asteroid, presents unique challenges. The lower gravity means that the spacecraft will experience less resistance and may have a harder time slowing down. Additionally, the surface of these objects may be uneven, making it difficult to land safely. Engineers must consider these challenges and develop specialized landing techniques for these environments.
5. How do scientists and engineers use mathematics to understand and navigate gravity during spacecraft landing?
Mathematics plays a crucial role in understanding and navigating gravity during spacecraft landing. Scientists use mathematical equations, such as Newton's laws of motion and the law of universal gravitation, to calculate the effects of gravity on the spacecraft. Engineers also use mathematical models and simulations to plan and test spacecraft trajectories and landing techniques, ensuring a successful landing mission.