How we will get to Mars and back

in space you don't travel in straight lines because ur a faggot with a Nazi rocket from the 1930s, so you need to cheat and use the gravity to pull you around like a limp wristed little bitch who refuses to sacrifice a few thousand people in human experiments landing people on the sun and stealing bits of it to jam into our new sun engines.

Also, if you did it like that, half way there, you would have to turn your ship around and full burn for the same amount of time that you burned towards the object. This way you will be moving at a sensible speed once you arrive. Both lengthening your travel time, and your fuel usage. Unless you want to arrive there moving at millions of Mps. Remember, until they arrive at Mars, they will be under the influence of Earth's gravity. And as things go up, they slow down, and as they fall they speed up. So, an intercept at their apoapsis means that they were able to use gravity to slow, and not fuel.

It still takes less time than a Hohman transfer.

Rockets. I'm going to say rockets.

Just make sure you have half a million dollars.

Elon will provide

>It still takes less time than a Hohman transfer.
As would teleportation. So what?

for the same reason you don't throw the football to the current position of the wide receiver but to the position where you expect him to be once the ball has traveled the distance

Speaking of Mars, why is it that in Robert Zubrin's Mars Direct plan the rocket is able to throw 47.2 tonnes on trans-mars injection, but the Hab and ERV only weigh 28-29 tonnes. What am I missing? Is all the remaining mass used for the landing system (aeroshell, landing thrusters etc)?

I want to dig Mars soil.

Because real life isn't a science fantasy space sim game. Mars isn't just going to sit there in space while you burn towards it, even if you had enough fuel to pull that shit off Mars will have moved off a ways since you started the flight.

REEEEe!!!!!!!!!!1

Missing stuff:
fuel for mid-trajectory corrections
fuel for matching Mars or (unshown aerobraking system and fuel to slow down enough to be captured and aim)
fuel to return to Earth?

no ones going to mars

the rover is in iceland, they use after effects to make everything red

sometimes it goes eslewhere

Mars surface is a lot more soily and a lot less pebbly. It doesn't look like Mars even when it's colored.

hush, you'l scare the retard

>dig Mars soil
Viking 2

>fuel to return to Earth?
H2 carried from Earth would be combined with Martian CO2 to make CH4 and O2

> Force applied mostly perpendicular to velocity
> Hardly any work done
> kek

Space travel does not work like it does in Star Wars.

That's pretty much essential (carrying enough fuel for the return trip is a non-starter). But it still means that you need to carry fuel-making equipment that's capable of making tonnes of the stuff in a reasonable time-frame. And you need to lift all of that fuel off of mars' surface (where the CO2 is).

Let's face it, this shit is an order of magnitude harder than what we've managed so far. Any manned mars mission within the next decade or two practically guarantees that no-one will make it back to earth alive. There are just too many "essentials" where failure of any one of them automatically means zero survivors.

>That's pretty much essential (carrying enough fuel for the return trip is a non-starter). But it still means that you need to carry fuel-making equipment that's capable of making tonnes of the stuff in a reasonable time-frame.
That's already in the pic with the ERV under Mars-Bound Only Payload. 5.81 tonnes for the hydrogen and 4.5 tonnes for "SP-100 Reactor" Zubrin wants to use a 100kW nuclear reactor on a rover to power the equipment for the Sabatier reaction and the follow-on reactions for producing fuel and oxidizer so that the reactor can be driven away from the ERV.
Plutonium gives off 540W of heat per kg. Converting that into electricity works at around 8% efficiency. So you need about 2.3 tonnes of plutonium, the rest is for the rover the radiation shielding the peltier elements, the chemical reaction equipment and the power cable.

Why go for the faster intercept? Are we impatient little bitches now? That will take more fuel to get that fast, and more to stop.

time is money m8
And I believe the main point for SpaceX is that they get their mars colonial transport back during that synod, so it can be prepped for launch in the next

It'd be better to carry your own return fuel regardless of the costs.

Once on site, you can do all the science to make legit martian-sourced fuel, proving that it can or can't be done. If it is the latter, you'll be really fucking glad you brought along your own return fuel.

>Converting that into electricity works at around 8% efficiency.
Stirling engines have 4x efficiency compared to old RTGs.
en.wikipedia.org/wiki/Advanced_Stirling_radioisotope_generator

>implying you couldn't send a small fuel generator first to prove the concept

>Stirling engines have 4x efficiency compared to old RTGs.
Yes, but also moving parts. That's always a liability if you can't stop by a repair shop.

Second that. I am dumb as shit but kerbal helped to offer a tangible experience with the whole apoapsis and periapsis business of using gravity to slingshot to orbital bodies.

Granted whenever I tried to play KSP I was barely on ork tier of aerodynamics, but hey

SpaceX is aiming for mars colonization
If they can't do IRSU then its a complete no-go

It's not another Apollo "Speed 200+ billion putting a man on the moon and have literally nothing to show for it afterwards"

>soily
>pebbly
Must you be so faggoty?

We can do it with an Orion drive.
The ASRG has essentially been cancelled

Zubrin laid out his plan in the early 90s. Since then PV efficiency skyrocketed because of the green energy boom. It'd probably be possible to use PV cells instead and even save weight. RTGs are going out of fashion except for the very outer reaches of the solar system. The Juno space probe sent to Jupiter already used just PV cells alone.

you are an idiot and missed the point

you are an idiot and missed the point

>answering a question is missing the point
you're the idiot. fuck off from Veeky Forums

if there's no geosocioeconopoliticoregano incentive, we won't be going to Mars

If there was one in say, the late noughties, we'd have been there by now.

But you didn't answer the question. You completely missed the point.

Of course you take the orbit of Mars into consideration you fuckwit.

Do you honestly think that the guy who asked the question didn't take the orbit into consideration or are you just that mentally retarded?

KYS
Y
S

>Do you honestly think that the guy who asked the question didn't take the orbit into consideration
yes. if he did, he would already have the answer to his own question

No?

The fuck are you on?

The problem isn't that Mars is moving; the problem is that it is extremely expensive to travel like that, since you will only be using fuel rather than the gravity of the Sun to sling you to the destination.

>The problem isn't that Mars is moving

Okay smartass - explain Mars movement in OP's picture isn't a problem, but suddenly is, if you were to move away from the sun?

Nice bait btw, keeps me replying.

again, you're the idiot. fuck off from Veeky Forums

:^)

again, you're the idiot. fuck off from Veeky Forums

:^)

>I... I was only pretending to be knock-out fucking retarded
It's time to go back

Jesus, this thread went full retard fast.
Keep it up Veeky Forums.

If you can't explain the science to a child, you either don't understand it, or shouldn't post.

But I'll take a shot at the troll...

Mars moving is, of course, a problem, but that's not what's fsking up 's rather intuitive, if wrong, idea.

The problem with said idea, is that you are literally fighting every gravitational force around, instead of using them to your advantage. There's not enough fuel on the planet, to launch a ship at Mars in a "straight line", defying all that force, and to slow it down enough to land before you pancake into it, given how large and heavy the fuel and rockets required to do all this would need to be. (Discarding various theoretical drives.)

In OP's version, gravity does most of that work for you, and your optimal return position is less than a year off, and it works fine with conventional drives.

...not that you can't do "closer" to a straight line and do a shorter distance, within the realm of feasibility, but in most cases, it wouldn't be much faster, and in all cases, you'd require a larger payload, causing more problems.

Because I feel bad for you, I'll try to make it understandable without using technical terms:

We put a lot of energy into achieving orbit - changing the force of gravity from causing us to fall back to Earth to causing us to circle around the planet. Then, we use a relatively tiny amount of energy to manipulate this orbit's shape such that we end up close enough to another planet to be pulled harder by its gravity than Earth. From there on, it's waiting with no fuel usage until you've arrived. This is "slow" but effective and doable.

The alternative suggested is to bypass orbiting entirely and fight gravity all the way to the point of being captured by the gravity of the destination object. Try to understand the difference in the most expensive part of the launch lasting until 160km+ distance from the planet, vs burning straight towards Mars for TWO HUNDRED MILLION km. Incredibly naively, treating entering orbit as much more expensive as it is, this is 1,250,000 times as much fuel usage.

Now consider how "wasteful" our current method is - the Saturn V rocket spent 6,000,000 lbs of fuel and was capable of lifting only 280,000 lbs of payload. Even if you could naively use a million times as much fuel for the same payload (which you can't, because now you need more fuel to compensate for the weight of the extra fuel), surely you see a problem with the again incredibly naive 8 quadrillion lbs of fuel.

If you have any complaints with my naive estimation, I assure you, the reality is WORSE, not better.

quadrillion -> trillion, but who cares, quadrillion is more accurate.

>Mars moving is, of course, a problem, but that's not what's fsking up
Actually, Mars moving is fucking up the straigt line approach every single time. Even if you start when Earth and Mars are closest together, at perihel opposition (55.6 million km Earth-Mars distance), and travel at the speed of light, you'd miss Mars. First, perihel opposition means Earth and Mars are 3:05 light minutes away from each other. So with the straight line approach you'd aim not at where Mars is but at where Mars was 3:05 minutes ago. Second, even if you travel at the speed of light, the journey takes time: again 3:05 minutes. So Mars will be out of position additionally by the same distance as the aiming error. In total, with the straight line approach Mars will be out of position by the same distance it travels in 6:11 minutes. Mars goes around the sun at a speed of ~24.077 km/s (that's the average speed; at perihel opposition it will be even faster). So in those 6:11 minutes Mars will have traveled ~8930.7 km on its orbital path. That's more than 2.6 Mars radii.
So even in the most favorable conditions you have to shoot not in a straight line at where you see Mars but at where Mars will be after the time of travel (including all the influences on the path by gravity, which even light undergoes), meaning OP's picture. And the reason is that Mars is moving.

>Actually, Mars moving is fucking up the straigt line approach every single time
No it doesnt, you just have to aim for slightly ahead (how much depends on how fast you end up going) ahead of where mars is when you start your burn, leaving aside the actual problem of fuel. This kind of trajectory is possible with an orion drive in theory

Which is exactly what I said.

Sure the orbit of Mars is a problem. But it does not become a new problem if you compare OP's picture with As I stated as well, the problem is that you won't be able to use gravity to assist you. Instead you would have to use a lot more fuel to achieve the shorter way.

Btw, I am

This guy knows what is up.

But I thought there was no gravity in space?

This. Can't believe people are still falling for NASA lies

How the fuck is a stirling engine 8% efficient?

>If you can't explain the science to a child, you either don't understand it, or shouldn't post.
I had a good laugh at this

they are testing rover technology on earth you retard

nobody in their rght mind would believe that this was mars

>we will get to Mars
What do you mean by "we", Peasant?

>No it doesnt, you just have to aim for slightly ahead (how much depends on how fast you end up going)
that's the fucking point of OP's pic as opposed to the straight line

how the fuck is your reading ability only 8% efficient?

>nobody in their rght mind would believe that this was mars
But thats the thing, user. People who believe that everything space-related is fake, tend to be quite crazy

OP's pic has the craft intercept mars almost halfway around a full orbit of the sun. Thats not "slightly ahead"

The point is to aim with lead. A straight line doesn't.

I'm , consider it a more introductory answer for then.

Do you disagree? Being able to introduce concepts to someone with less knowledge than you is a sign of deeper understanding than repeating what you've heard. There is a reason it is said that you do not truly understand a subject until you can teach it.

I expect this is bait, but just in case, gravity always exists but gets weaker with increased distance. What "cancels out" gravity is gaining enough horizontal movement relative to the body that in some sense gravity causes you to "fall but miss" which is the basic intuition of an orbit.

People are still missing the point of the question and responding with tangential issues. With basically infinite energy, you COULD do a straight line launch towards the position that Mars will be in by the time you get there. Leading is not the issue, the energy cost of not abusing orbital mechanics is.

to do that, your rocket would have to:
1: cancel earth's velocity around the sun.
2: accelerate towards mars.
3: accelerate to match mars' orbital velocity.
that's much much much more than our rockets can do.

You could actually do that in 2 steps.
1) accelerate to escape velocity for the sun, pointing in the normal direction to Earth's orbit
2) slow down once you are near mars

However, this is still a lot of delta-v, my calculations put it at 71 km/s, which, assuming a dry mass of 10 tons and an average specific impulse of 300 s, is more fuel than 10^106 kg

woops, made an error with the last part- 10^14 kg. I knew it didn't sit right with me.

>With basically infinite energy, you COULD
fuck off from Veeky Forums

Excellent comprehension, sir. Not actually infinite energy, but as I suggested in my previous post, an absolutely insane amount of energy (or efficiency!) compared to technology we actually have.

The point wasn't that it's possible, the point is that half of you motherfuckers are complaining about the wrong aspect and that is why the people you are arguing with keep coming back to say BUT YOU GOT IT WRONG.

Learn to fucking argue. Or fuck off from Veeky Forums.

A straight line from where earth is to where mars will be in a few days does

And OP's picture is a straight line from where Earth is to where Mars will be in a few months time. That the line is then bent is due to gravity, not by steering the spaceship around a curve. So with this insight there's no difference anymore between OP and the silly question except the degree of bending, right? Wrong! This was the point all along. That you aim for where the target is AFTER the time of travel. This was the point of the criticized postings here: and here: which, as one idiot alleged, missed the point. But they didn't. They said in a simple and easy to understand way what's the matter.

>as one idiot alleged, missed the point. But they didn't.
There are two individual problems with the suggestion, and we both see the opposite problem as more important. I will continue to argue however that considering the number of people who continue to post things like , it seems that focusing on your problem is not satisfying those who were seeking an answer.

>So with this insight there's no difference anymore between OP and the silly question except the degree of bending, right?
This is exactly the point. The only difference between OP's picture and the second one is that one flies a much more direct route than the other. There is no reason to assume that in the second picture the rocket is aiming at where mars currently is rather than slightly ahead

>There is no reason to assume the rocket is aiming at where mars currently is rather than slightly ahead.
Why didn't he draw that then, instead of a completely straight line pointing directly at the planet where it currently was?

Because it was thirty seconds in paint and meant as a joke? It would actually be more like pic related

>Do you disagree?
not really. I just found it funny, because it implies that some anons are children

>Degenerate parabola not normal to the surface of the sun
Stop talking if you don't know orbital mechanics.