Rocket Propulsion: Calculating Specific Impulse for Return Mission

[praveenpandiyan]

1. well. I have this question. That my rocket is launched from mar in an return mission to earth. To calculate specific impulse of the rocket. Should i consider mar or Earth gravity and if why!? Help me with this

 

[SteamKing]

If your rocket is being launched from Mars, why would you use Earth's gravity in your calculations?

 

[praveenpandiyan]

problem Is we have formula for specific impulse for Earth standard..That Isp=Cj/Go
Cj-effective jet velocity
Go-gravity
..and that's the reason i asked..why its not Mars gravity! I am not sure of it.

 

[SteamKing]

problem Is we have formula for specific impulse for Earth standard..That Isp=Cj/Go
Cj-effective jet velocity
Go-gravity
..and that's the reason i asked..why its not Mars gravity! I am not sure of it.

That's because until now, all rockets have been launched from earth, in Earth's gravity. If ever a probe lands on Mars and returns to Earth from there, obviously, Mars gravity will determine how much impulse will be required for the rocket to return to earth. It's like when Apollo went to the moon: did the lunar module need to exceed the gravitational pull of the moon or the earth?

If you had used the HW template per the rules of this forum, and provided the entire question as worded originally, perhaps this confusion of yours could have been resolved by now.

 

[HalfLostAndSearching]

When calculating the specific impulse for a rocket propulsion system, it is important to consider the gravitational forces of both Mars and Earth. This is because the specific impulse is a measure of the efficiency of the rocket, and the strength of the gravitational pull can affect the amount of thrust that the rocket can generate.

For a return mission from Mars to Earth, the rocket will be launched from Mars, so the gravitational force of Mars will play a significant role in the initial stages of the launch. However, as the rocket travels towards Earth, the gravitational force of Earth will become more dominant.

In order to accurately calculate the specific impulse, you will need to take into account the changing gravitational forces of both planets throughout the journey. This can be done by using a mathematical model that takes into consideration the distance between the two planets and their respective gravitational forces.

Additionally, the specific impulse may also be affected by other factors such as atmospheric conditions and the design of the rocket itself. It is important to consider all of these variables in order to accurately calculate the specific impulse and ensure a successful return mission from Mars to Earth.

I hope this helps to clarify the importance of considering both Mars and Earth gravity when calculating the specific impulse for your rocket propulsion system. Good luck with your mission!