This question is about our Solar System.
Which of the following forces is responsible for maintaining the orbits of planets and satellites in our universe?
Earth and Mars are planets in our Solar System. The table shows some data for these planets.
| Planet | Radius of orbit in km | Time of orbit in Earth days |
|---|---|---|
| Earth | 150 000 000150\,000\,000150000000 | 365 |
| Mars | 228 000 000228\,000\,000228000000 | 687 |
Calculate the orbital speed of Mars in km/day. Give your answer to 2 significant figures.
The distance between Earth and Mars varies significantly over time (between approximately 56 million km and 401 million km). Explain why this distance is not constant.
Scientists communicate with a robotic rover on the surface of Mars using radio signals that travel at the speed of light, 300 000 km/s300\,000\text{ km/s}300000 km/s.
Show that when the planets are 240 000 000 km240\,000\,000\text{ km}240000000 km apart, it takes exactly 800 s for a signal to travel this distance.
A scientist on Earth sends control signals to steer the rover on Mars. The rover is programmed to move at a very low speed, limited to 0.04 m/s. Suggest why the speed of the rover is kept so low.
