Question

Part 1.
When a vehicle is passing through the atmosphere, at some point it may decelerate at a rate of 49.2 m/s² (away from the centre of Earth) while Earth's gravitational pull remains at -9.80 m/s².
a) In such a situation, what is the apparent weight in g's of an astronaut inside the vehicle?
b) In this situation, is the astronaut in a micro-gravity situation.

Part 2.
A space vehicle is in orbit around a planet and moving in a clockwise fashion. If the vehicle wants to move to a lower orbit, should the first rocket firing aim to decelerate or accelerate the vehicle, and similarly, what should the second firing of the rockets aim to do?

Part 3.
If a space vehicle re-enters Earth's atmosphere at too shallow an angle, what will happen to the vehicle and why?

Part 4.
In using the gravitational field of a planet to propel a vehicle farther into space, what two important quantities are conserved?

Part 5.

What is it about the position of the three antennas in NASA's Deep Space Network (DSN) that allows Earth-based observers to keep in contact with vehicles deep in space?

Answer 1

part 3:

If the angle is too shallow, the craft will experience a ‘skip’.

The ‘re-entry skip’ is often misunderstood as ‘bouncing off the atmosphere’. In fact it just means that the craft does not slow down enough to start losing altitude, therefore it pierces the top layer and exits it. Inevitably, it returns some time later and it may even do several such ‘skips’ (hence the analogy with skipping stones). If the skip is not intended, the craft will land somewhere completely different than planned.

A skip (or even several skips) can be intentionally used for a re-entry, e.g. to reduce the maximum heat load. So far the guidance computers were not capable enough to reliably perform such a re-entry. Future craft with better computers and better maneuvering capabilities are more likely to use skips.