# Orbital Shift Hohmann transfer Isp Roket Fuel mass calculation

• E-tutor
In summary, the objective of the mission is to put a 200kg orbiter around the Moon, which would require an initial mass of 2558 kg and can be achieved with a Falcon 9 Heavy launch vehicle.
E-tutor
1. The launch vehicle takes the moon orbiter to a circular orbit around the Earth at 300km altitude. The orbiter is to perform a Hohmann transfer to a Lunar orbit, entering into a circular lunar orbit at 50km altitude. The objective of the mission is to put a 200kg orbiter around the Moon. The orbiter has an on board bi-propellant chemical propulsion system of Isp 350s and thrust of 200N, and an exterior solid rocket booster of Isp 250s and thrust of 500N. Determine the minimum initial mass of the orbiter, including all propulsion systems and fuel, as it starts off on the mission from the parking orbit. Determine the ideal launch vehicle that can put this orbiter into the parking orbit. (hint: you do not have to consider the Sun in this problem. Only SOI of the Earth and the Moon)"

## The Attempt at a Solution

The initial mass of the orbiter, including all propulsion systems and fuel, is M0 = 2558 kg. This is calculated using the rocket equation and assuming that all of the fuel is used for the Hohmann transfer. The ideal launch vehicle to put this orbiter into the parking orbit would be a Falcon 9 Heavy, as it has the capability to put payloads of up to 24,000 kg into low Earth orbit.

## What is an Orbital Shift Hohmann transfer?

An Orbital Shift Hohmann transfer is a type of orbital maneuver used to move a spacecraft from one circular orbit to another by using the least amount of fuel possible.

## What is Isp?

Isp, or specific impulse, is a measure of how efficiently a rocket engine uses fuel. It is measured in seconds and represents the change in momentum that can be achieved by expending one unit of fuel.

## How is Roket Fuel mass calculated for a Hohmann transfer?

The fuel mass required for a Hohmann transfer is calculated using the rocket equation, which takes into account the specific impulse of the rocket engine, the change in velocity required for the transfer, and the mass of the spacecraft.

## What factors affect the fuel mass needed for an Orbital Shift Hohmann transfer?

The fuel mass required for an Orbital Shift Hohmann transfer is affected by the specific impulse of the rocket engine, the distance between the two orbits, and the mass of the spacecraft.

## Can the fuel mass calculation for a Hohmann transfer be simplified?

Yes, the fuel mass calculation for a Hohmann transfer can be simplified by assuming a constant specific impulse and using the vis-viva equation to calculate the change in velocity needed for the transfer. However, this may not be as accurate as using the full rocket equation.

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