1: How could you travel between tidally locked planets?

2: How long will it take the tesla in space to turn white (be bleached)

3: In which direction is orbit around mars achieved easiest?

4: How could you calculate a brachistochrone transfer burn with a changing acceleration?

5: How fast should a rocket be going in order to leave the atmosphere within 5 seconds? (Ignore G-forces, air resistance and such)

6: Why space elevators are essentially impossible to construct?

7: What factors effect the rockets thrust?

8: Why is perpetual motion drives are impossible to construct?

9: Why are SSTO's hard to construct? (Hint: shape of the engine)

To finish this off, here is a hard rocket science related problem.

10: A space probe is traveling in outer space with a momentum that has a magnitude of 3.87 x 107 kg·m/s. A retrorocket is fired to slow down the probe. It applies the force to the probe that has a magnitude of 1.41 x 106 N for 9.55 seconds and a direction opposite to the probe's motion. Determine the momentum of the probe after the retrorocket ceases to fire.

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• @Jerba The atmosphere moves with the earths rotation. Since there is no air in space and it just a vacuum, the top of the elevator will just stay in place until the motion from the bottom reaches it and thus it will cause it to bend and you get the idea.

1.3 years ago
• 22 Jerba

Space elevators are also impossible to construct because of the atmosphere. Im just guessing, but wouldn't it start burning from the atmosphere or does the atmosphere move with the earths rotation?

1.3 years ago
• @AstronautPlanes If you are asking about SSTO's, then the answer is no. There are multiple articles and research papers on this online.

1.3 years ago
• @FalconNinja Did you extracted that info from Scott Manley??

1.3 years ago
• @Phoza Actually majority are correct. For number 9, you can scroll down. I posted the answer in a reply.

+1 1.3 years ago
• 100 Phoza

I think I know a few:
1 (Guessing): Brachistochrone Maneuver?
3: Counter-clockwise
5: 20 km/s
6: As you recede from earth, gravity becomes weaker, forcing the pod at the end of the elevator to essentially "slow down". Also, considering the length of the elevator and speed of rotation of the earth, it would be difficult to construct a cable that could withstand the enormous centrifugal force.
7: Varies on type of fuel (liquid or solid), but the two main factors are the composition of the fuel and the shape & size of the engine nozzle.
8: The laws of thermodynamics don't allow it. Friction would cause the materials used to erode away, eventually becoming useless in a perpetual motion machine. Even without friction, the individual protons of the atoms are theorized to decay over trillions of years, technically not being perpetual.
9: (Mostly just guessing). An engine's nozzle's efficiency depends on the outside conditions. While one shape may be suited for atmospheric flight, it would perform horribly in outer space. An SSTO would need an engine that performs well in both environments.

these might all be garbage though lol

+1 1.3 years ago
• @PriyanshuRoy i believe that is in fact correct.

1.3 years ago
Given initial momentum is 3.87107 N s or 414.09 N s,Force applied by engine in 1 sec is 1.41106 N or 149.46 N,for 9.55 s. Therefore change in momentum is 149.46 N * 9.55 s ,or 1427.343 N s . Since it's a retro rocket boost,the momentum will decrease for probe,by subtracting 1427.343 N s from 414.09 N s,giving us -1013.253 N s. It will go in opposite direction.
PS space between the number represents product. Don't know why it doesn't show star character.

1.3 years ago
• 6: Since earth is rotating, thus this elevator would act as a huge whiplash.

1.3 years ago
• Question 8: Due to first or second law of thermodynamics.

1.3 years ago
• @PriyanshuRoy Ye it is 20km/s. It is quite easy but if you want to challenge your self you may go ahead and take into account the other factors.

1.3 years ago
• @TNTblast500 That is correct, i have mentioned that below in the comments as well.

1.3 years ago
• No. 9 SSTOs are so hard to make because because of the way rocket engines use to direct their thrust(a bell) because to get maximum efficiency the chamber pressure has to be equal to the atmosphere around it meaning you need a narrow and small bell at sea level and a wide and large bell in a vacuum and because rockets go straight up the first stage engines become less and less efficient(unless they were designed to be more efficient higher up) so you need to change to another engine(this is one of the main reasons rockets are multistage the other being there is no need to carry empty fuel tanks) the solution to this is to use a aero spike engine which uses a spike instead of a bell the way it works is at lower altitudes there is greater air pressure that presses on the spike threrefore there is a narrow virtual bell formed but at higher altitudes threre is lower air pressure which puts less pressure on the spike therefore a wider virtual bell is formed but aero spike engines are still in development and we won’t see them used a lot in quite a while.

1.3 years ago
• No 5-
Taking atmosphere's height to be 100 km or 1*10^5 m.
A rocket at sea level 0m would take 5 seconds to cross atmosphere.Therefore by formula v=s/t,we get required velocity as 20000m/s.By neglecting gravity and air resistance, you've made it much easier.

1.3 years ago
• @AstronautPlanes hahaha exactly.

1.3 years ago
• @FalconNinja (and Jundroo said) THIS IS ROCKET SCIENCE!!!

1.3 years ago
• @NazyaMilitare i wish haha

1.3 years ago
• @AstronautPlanes That is correct, however another reason is due to the thruster shape. All the SSTO vehicles use a bell shaped nozzle for all altitudes. This is a problem since as you ascend the air pressure changes. Lower air pressure means that gasses can expand more. For example in multi staged rockets, the shape of the engine is optimised. In lower altitudes, the bell is shorter and opposite in a vacuum. Having a bell that is only optimal at a single altitude lowers the overall engine efficiency. Essentially, these big bell shaped nozzle at high altitude expand the gases so much that it exhaust gases down to near vacuum pressures (no thrust forward).

+1 1.3 years ago
• I'll answer 9, they are hard to construct, because you need more fuel to enter orbit, but you also need more engines to lift that weight, that makes less Delta-V, so you add more fuel... And so on.

In KSP is easy to make one, because of the low Delta-V requiered for orbit, but in real life it is super difficult because of the huge Delta-V requiered, that's why almost all rockets use more than one stage.

1.3 years ago
• The meaning of life, the universe, and everything

1.3 years ago
• 42

+1 1.3 years ago
• Jesus is the answer ...
Jesus is always the answer !

1.3 years ago
• @PriyanshuRoy Thanks for the feedback, i will change it now.

1.3 years ago
• You could have said 1.41*106 N for 9.55 s.

1.3 years ago
• In the last question,@FalconNinja ,the force is net force applied or force applied in 1 second,say clearly.

1.3 years ago