How long would it take to travel from Venus to Mars with a solar sail?
Let's say the ship is 500 tons. Let's say the sail is 100 meters times 100 meters.
I might want to use that in a book I am writing at the moment, can you tell me /sci/?
>>7927744
Interesting proposition. Do you have any idea the ammount of calculations you are asking for? I will give it a shot unless I get bored.
>>7927752
There is quite a lot of info about calculating the properties of these sails on the wikipedia article, but I don't have any science education beyond high school so I am understanding fuck all to be honest.
https://en.wikipedia.org/wiki/Solar_sail
>>7927744
A long damn time, because you'll need to swing around planets to use them to sling shot the ship to Venus. On the final approach, you won't be able to use the sail itself, unless you use the previous trajectory that puts you between the sun and venus.
>>7927744
You can travel faster than light with a solar sail. My credible scientific source for this assertion is an even shittier than usual episode of DS9. I want to believe and I'm into verbal masturbation in a big way though, so IT'S REAL.
>>7927790
The starting point would be Venus, assume the ship was build there and is already in orbit.
Could the ship use Earth to gain speed on the way to Mars?
>>7927744
>Let's say the ship is 500 tons. Let's say the sail is 100 meters times 100 meters.
Well that is much, much, much too small to be useful. A 100m by 100m solar sail would generate about as much force as the weight of a pencil. By my rough calculations, after about 1 YEAR of thrust, your 500 ton ship would be going... 5 meters/second
>>7927803
Well fuck. Do you have formula where I can plug in the sail size?
It's science fiction after all I could increase the sail size probably and talk about some techno babble materials.
How long would it take with a sail that is 10km x 10km?
Wiki shows reflective radiation pressure is
[math]P_{reflect}= \frac{2W}{cR^2} \cos^2 \alpha[/math] Pascals, where
solar constant W = 1361watt/m2
speed of light c = 3e8 m/s
R = distance from Sun in AU
α = incident angle
so your one-hectare reflector near Venus (0.72AU) at a 45° angle (for tangential acceleration) would give 123milliNewton force.
>>7927848
>123 mN
>500 tons = 453592 kg
That would be
2.712 m/s^2 for 500 tons?
And the acceleration decreases while getting further away from the sun? Do you know how the minimum for Mars?
>>7927744
>Let's say the sail is 100 meters times 100 meters.
Try 10 kilometres by 10 kilometres in a ship that's 100 tons and then we might be talking in useful travel times.
What is the impediment to making the sail out of graphene?
>>7927875
>500 tons = 453592 kg
>using Murikan short ton
fgt pls
>>7927797
If the planets are aligned properly then sure you could slingshot around the Earth to be thrown to Mars.
>>7927803
>>7927816
There is a formula for sail size on the wikipedia article but 100m^2 is far to small like the other guy said. 100km^2 would be more feasible.
We can simplify the model by taking the sail to be 100% efficient and finding out at Venus' distance from the sun how many Newtons per m^2 you would get for your sail.
Then you would have F in the F=ma equasion. Rearrange for a to be a=F/m and you have the useful accelleration for your ship.
Then you would need to check a delta v chart of the solar system to find out how many km/sec speed change you need to get from Venus to Mars.
Finally you would need to plot a transfer course from Venus to Mars, find the distance of that and use t=d/v to get your answer.
And there are some calculations that I am missing, like how to relate the constant a from your solar sail into velocity.
I could try and give you an answer but it would take days.
>>7927797
>The starting point would be Venus
Shit, I for some reason thought it was Mars to Venus.
>Could the ship use Earth to gain speed on the way to Mars?
Yes, but only if you have a window for doing so. The planets may not be in the right places for it.
>>7927952
Can you take a guess in regards of the time frame we are talking about?
>>7927978
OK: Uneducated guess: 2 years one way.
I'll try and plod along and get you something a bit more feasible. No doubt this thread will have 404d by then so look on /sci at this time for the next 3 days. I'll use the pic from the OP.
>>7928017
Thank you kind anon
>>7928017
23.45 months
>2345
Heh. neat
>>7927744
>The total force exerted on an 800 by 800 meter solar sail, for example, is about 5 newtons (1.1 lbf) at Earth's distance from the Sun
the pressure must get lower as it get further away from the sun, so it must be a hell to calculate it, as acceleration will drop.
>>7927744
Ray Bradbury called some random fireman and asked him to look up the burning temp of paper.
The answer he got and used (451 Fahrenheit) is famously wrong.
Do your own fucking science.
This is the force equation
>>7928053
It does and acceleration would drop however the force of the suns gravity decreases with distance as well. That's why im not going to try and model every force on the ship. It would be more accurate but it requires a shitload of extra work for some (hopefully small) increase in accuracy.
>>7927744
Calculate the magnitude of the Poynting vector and use that as your radiation pressure. Drop the magnitude of the E and B field by the 1/r^2 factor as you get away from the sun, integrate across the sail area and on the travel path
Easy, done.
>>7927791
Top geg, underrated post. DS9 was shit.
