FAQ: Clear Up the Jargon
Open a question for the short answer. Follow the linked guide when you want the connected explanation.
Why do satellites not fall straight down?
They are falling, but their sideways velocity carries them around Earth. Gravity bends their path rather than holding them motionless.
Do satellites need engines running all the time?
No. An ideal orbit needs no continuous thrust. Real spacecraft may use propulsion to adjust an orbit, counter disturbances or carry out disposal.
Is there gravity on the International Space Station?
Yes. Gravity remains substantial at the station's altitude. The station and its occupants are in continuous free fall together, producing the familiar weightless experience.
Is a geostationary satellite really stationary?
It moves around Earth while matching Earth's sidereal rotation in a circular equatorial prograde orbit. It therefore appears nearly fixed to a ground observer.
Why does a satellite signal get weaker with distance?
Transmitted energy spreads over a growing area. In ideal free space, doubling distance reduces received power to roughly one quarter when the other link conditions stay unchanged.
Can optical Earth-observation satellites see through clouds?
Ordinary visible and near-infrared surface imaging is obstructed by clouds. Radar can observe through many clouds, but it measures a different physical interaction and is not a substitute for every optical measurement.
What is the difference between a payload and a bus?
The payload performs the mission's main task. The bus supplies shared support such as power, structure, temperature control, computing and pointing.
Does a rocket push against the air?
No. It accelerates exhaust and receives thrust through conservation of momentum. A rocket can therefore work in a vacuum.
What makes hardware space-ready?
There is no single universal label. Equipment must be shown suitable for its mission's loads, vacuum, temperature, radiation and operational requirements through appropriate analysis and testing.