16k views

### What is the oldest artificial satellite still in use?

Wikipedia states that Vanguard I is the oldest artificial satellite still in orbit. What is the oldest that's still in use?
5k views

### Minimum Orbit Altitude

What is the minimum altitude required for a Cubesat*-like object to orbit around the Earth? Could you initiate an orbit inside the Earth's atmosphere? *A CubeSat is a 10 cm (1 liter) cube with a mass ...
5k views

### How hard do you have to throw something off the ISS to make it deorbit?

During Expedition 41 Reid Wiseman and Alexander Gerst replaced a failed pump on the outside of the ISS. I am guessing they took the broken pump back inside the ISS and returned it to earth in one of ...
16k views

### Why is the life span of a LEO satellite less than that of a GEO satellite?

The average life span of a LEO satellite is approximately 5 years, but the average life span for a GEO satellite is approximately 8 years. Why is this?
13k views

### How long would ISS stay in orbit if it didn't get reboosts?

Apparently ISS is so close to Earth's atmosphere that it requires periodical boosts to stay in orbit. If the station were completely abandoned and it wouldn't get the boosts anymore, how long would it ...
21k views

### Can an artificial satellite stay in orbit forever?

If an artificial satellite is in orbit around the Earth, it collides with dust and gas and loses a very small amount of kinetic energy to these collisions, and eventually will spiral down towards ...
15k views

### Does the orbit of the ISS decay?

Does the orbit of the ISS decay? I don't know much about the ISS, but I heard some rumors. The rumor I heard was that there is a very, very tiny atmosphere at the ISS orbit.
3k views

### Why do malfunctioning satellites come back to Earth?

In school, I learned that if a satellite moves at a speed $\sqrt{gR}$ (the square root of the product of the acceleration due to gravity and radius of the Earth), then it will remain in Earth's orbit. ...
2k views

### Orbital altitudes, are some better than others and why?

The geostationary orbit of about 35,786 km above mean sea-level allows satellites to rotate at the same speed as the Earth on its axis, making them seem as if they don't move relative to the ground. ...
267 views

### How long would a satellite fly on a sun-synchronous 600km orbit?

How long would it take for a 12U cubesat on a circular polar orbit with altitude 600 km to fall down to 500 km? Please, add references/calculations to your answer.