Can a spaceship be powered solely by solar energy?

[Mayed Al-Tunaiji]

Hello, PF. So I was wondering if it's possible to power a spaceship by solar power only. If so how big will the solar panels be? Where would they be installed? How long will it take for them to fully charge in order to travel a certain distance? between Earth and the moon for instance.

 

[Vanadium 50]

Building such a rocket could revolutionize space exploration since the mass will be reduced significantly along with the cost of building a spacecraft .

That's an unfounded claim.

A moon shot takes in the ballpark of 1 TJ of energy. The solar constant is in the ballpark of 1 kW/m2. So you need acres upon acres of solar panels. Which you then have to lift, which requires more energy, which requires more solar panels, and so on and so on.

 

[Mayed Al-Tunaiji]

That's an unfounded claim.

A moon shot takes in the ballpark of 1 TJ of energy. The solar constant is in the ballpark of 1 kW/m2. So you need acres upon acres of solar panels. Which you then have to lift, which requires more energy, which requires more solar panels, and so on and so on.

Sorry but I thought that using renewable energy is going to increase the efficiency of the rocket.

 

[russ_watters]

Sorry but I thought that using renewable energy is going to increase the efficiency of the rocket.

No, "efficiency" is not a relevant concept when discussing different energy sources and wasn't what you posited anyway: you speculated about COST, making the classic solar energy mistake that assuming since the source energy is free that the total lifetime cost of the system will be lower. It doesn't follow...and the cost follows the weight issue. So you're basically assuming that solar panels are approximately free and weigh approximately nothing.

In any case, such spacecraft do exist on a weaker scale: https://en.m.wikipedia.org/wiki/Dawn_( spacecraft )

They have high propulsive efficiency, but low power to weight ratios, so they are never going to be viable for a trip to the moon. For very long trips they collect a lot of energy, which is where they provide a lot of benefit.

 

[unix101os]

First you would need some form of electrical propulsion which currently isn't very practical. You would also still need fuel to get into orbit. A nuclear reactor would probably be more practical given you have a good source of propulsion that only uses electricity.

 

[Ken Fabos]

Proposals like in the Asteroid Retrieval Feasibility Study by Keck Institute for Space Studies are based on solar powered propulsion but it sounds like a case of "if or when someone else does the development work".