What happens to a spacecraft in flyby Mission?

Question

I am not a science guy, So I have couple of questions

I want to know what happens to a spacecraft whose mission is to flyby a planet E.G. Mariner 4

Also Viking 1 (lander mission) is it still on mars? are they still operating it from earth?

How do they operate, are there already defined algorithms by which robot automatically do research or we do it from there?

After getting into the space, it does not need to be propelled by engine, right?, but in between if have to change its direction, how can we do that.

Changing direction of a spaceship won't work like Air-plane does!

While sending a spacecraft into the space is it better to send it perpendicular to the earth surface(I think the time of resistance should be less).

Okay last one, have we ever sent some spaceship in to the SUN or near sun(how close man-made spaceship can go to the sun), flyby mission can flyby and go in to the sun.

And I also want to know if a spacecraft start revolving on its own axis, can astronauts stop its revolution?

Answer 1

1. Depends on the velocity of the spacecraft. Mariner 4 is currently orbiting the sun as it did not have enough velocity to escape its gravitational pull. New Horizon's, which visited Pluto, though, is moving so fast that it will escape our solar system altogether and start orbiting the center of our galaxy.

2. Yes, it's still there, but it's not operational. The duration over which a lander can operate depends on the energy it has available and the nature of the source providing that energy. Solar power keeps the opportunity rover crawling over Mars, but when the plutonium core in curiosity decays, it will not have the energy necessary to operate. Opportunity could go on for as long as its solar panels manage to avoid getting covered in dust or simply decay.

3. It depends. We send commands to the curiosity rover on Mars (hey that looks interesting, tell the rover to head over there) but in the case of New Horizon's the distance to the spacecraft and the time it takes radio signals to travel out there meant that everything it did during the Pluto flyby had to be programmed in advance of the flyby.

4. Not sure what you are getting at, could you try to explain further?

5. Noops, not yet. We have spacecraft that observe the sun, but the immense heat and gravity close to the sun mean that as of now we do not have the means to put a spacecraft in a trajectory that will bring it close to the sun and expect it to survive that pass (to understand what I'm getting at, youtube sun grazing comets and have fun watching them get torn to shreds as they swing around or crash into the sun).

6. Spacecraft can indeed change their rotation using so-called reaction wheels. Reaction wheels on kepler failed a few years ago, which is why it can only observe a limited part of the sky - it can't change its rotation.