3 days to Mars. How fast?

[ImmaStegosaurus!]

I have ran into claims that new witchcraft engines could get us to Mars in three seconds*. These claims do not care to mention if three days include deceleration or if it's just a fly past. I'm not smart enough to calculate acceleration required or final velocity near Mars but I feel brain matter is very much present on these forums.

So, assuming that 3 days claim includes deceleration for half the distance and that things go wrong at worst possible moment in mid way I'd ask how fast would a spacecraft shoot past Mars if braking was not possible? How far would this velocity take the craft and would it escape our solar system?


* Typo but too funny to fix!

Edited March 28, 2016 by ImmaStegosaurus!

[PB666]

1 minute ago, ImmaStegosaurus! said:

I have ran into claims that new witchcraft engines could get us to Mars in three seconds. These claims do not care to mention if three days include deceleration or if it's just a fly past. I'm not smart enough to calculate acceleration required or final velocity near Mars but I feel brain matter is very much present on these forums.

So, assuming that 3 days claim includes deceleration for half the distance and that things go wrong at worst possible moment in mid way I'd ask how fast would a spacecraft shoot past Mars if braking was not possible? How far would this velocity take the craft and would it escape our solar system?

100,000,000,000 meters over 300,000 seconds = ~ 1/3 million m/s If earth transects mars. If mars is on the opposite side of the sun then its around a million meters per second. speed of light is around 300 million meters per second.

[Bill Phil]

Depends on where Mars is. Although, this would probably be a point and click drive anyways.

[UmbralRaptor]

3 hours ago, ImmaStegosaurus! said:

I have ran into claims that new witchcraft engines could get us to Mars in three seconds. These claims do not care to mention if three days include deceleration or if it's just a fly past. I'm not smart enough to calculate acceleration required or final velocity near Mars but I feel brain matter is very much present on these forums.

So, assuming that 3 days claim includes deceleration for half the distance and that things go wrong at worst possible moment in mid way I'd ask how fast would a spacecraft shoot past Mars if braking was not possible? How far would this velocity take the craft and would it escape our solar system?

Er, which is it?

In any case, assuming a 3 day (259200 s) brachistochrone, one can get get reasonable numbers by playing with the kinematic equations:

t == 259200/2 == 129600 s (we only need to work out half-way)

x == 5.46e10 m (opposition with Mars at perihelion and Earth at aphelion) to 4.013e11 m (conjunction with both planets at aphelion)

a == 2*t^-2*x/2 == t^-2*x == 3.25 m/s² to 23.89 m/s²

v_max == a*t == 421 km/s to 3096 km/s (0.0014 c to 0.0103 c)

Δv == 2*v_max == 843 km/s to 6193 km/s.

Sure, the acceleration in the first case is low enough that gravity sort of matters, but given the absurd ΔV, not as much as one might think. If there's a coast phase, expect higher accelerations to keep within the time limit.

Assuming some sort of impulsive accelerations, the speeds run from 211 km/s to 1548 km/s (with expended ΔVs of 421 km/s to 3096 km/s.)

Edited March 27, 2016 by UmbralRaptor

[Mitchz95]

12 hours ago, ImmaStegosaurus! said:

I have ran into claims that new witchcraft engines could get us to Mars in three seconds.

 

12 hours ago, ImmaStegosaurus! said:

could get us to Mars in three seconds.

 

12 hours ago, ImmaStegosaurus! said:

three seconds.

 

Uh...

[WestAir]

He obviously meant 3 days, as per the Thread Title and the entire rest of his OP. No need to dig into an obvious mis-type.

That said, I doubt we'll ever see 3 days to Mars. That's how long it takes to get to the moon.

[Mitchz95]

56 minutes ago, WestAir said:

He obviously meant 3 days, as per the Thread Title and the entire rest of his OP. No need to dig into an obvious mis-type.

That said, I doubt we'll ever see 3 days to Mars. That's how long it takes to get to the moon.

I was just poking fun at it. No insult intended.

[hendrack]

Russians haven been developing a new nuclear engine, claiming to reach Mars in 45 days. http://sputniknews.com/russia/20160302/1035657122/engine-rosatom-space.html

[fredinno]

1 hour ago, hendrack said:

Russians haven been developing a new nuclear engine, claiming to reach Mars in 45 days. http://sputniknews.com/russia/20160302/1035657122/engine-rosatom-space.html

And Americans have been developing an ION engine called VASMIR capable of reaching Mars in 3 Days

Neither is going to happen, because there is literally no point right now for such a fast Mars transfer.

[Bill Phil]

1 hour ago, fredinno said:

And Americans have been developing an ION engine called VASMIR capable of reaching Mars in 3 Days

Neither is going to happen, because there is literally no point right now for such a fast Mars transfer.

I thought it was 30...

[ImmaStegosaurus!]

Yeah, proof reading failed me this time! 3 second flight to Mars would be interesting experiment in smashing (living) things through space ship though.

 

[UmbralRaptor]

17 hours ago, Mitchz95 said:

Uh...

@ImmaStegosaurus! *did* say it was powered by witchcraft.

I'd still be suspicious of any flight that claims to get to Mars in a few weeks and isn't an Orion or Zubrin drive, though.

[RocketSquid]

5 hours ago, UmbralRaptor said:

@ImmaStegosaurus! *did* say it was powered by witchcraft.

I'd still be suspicious of any flight that claims to get to Mars in a few weeks and isn't an Orion or Zubrin drive, though.

I think he's talking about the cannae drive/EmDrive, which don't carry their own propellant, leading to a very light ship.

[fredinno]

12 hours ago, ImmaStegosaurus! said:

Yeah, proof reading failed me this time! 3 second flight to Mars would be interesting experiment in smashing (living) things through space ship though.

 

Yeah... You're probably better off putting living beings in particle accelerators.

[winged]

On 26.03.2016 at 3:54 AM, ImmaStegosaurus! said:

 would it escape our solar system?

It would escape our galaxy with such speed (500km/s).

Edited March 28, 2016 by winged

[GDJ]

I would be happy with 3 months from here to Mars. That's pretty fast and some stiff acceleration right there.

[ImmaStegosaurus!]

3 hours ago, winged said:

It would escape our galaxy with such speed (500km/s).

That makes months long journey and free return trajectory sound like really good way to do things. Only way to do things.

[Kerbart]

On 3/27/2016 at 9:54 PM, ImmaStegosaurus! said:

I have ran into claims that new witchcraft engines could get us to Mars in three seconds. These claims do not care to mention if three days include deceleration or if it's just a fly past. I'm not smart enough to calculate acceleration required or final velocity near Mars but I feel brain matter is very much present on these forums.

I'm pretty sure that the acceleration required for a 3 second trip (ignoring unimportant issues like breaking the speed of light) will ensure that there will not be a lot of brain matter left after arriving.

Yes; I know you meant 3 days. But that wouldn't make it nearly as funny.  

[WestAir]

20 hours ago, Kerbart said:

I'm pretty sure that the acceleration required for a 3 second trip (ignoring unimportant issues like breaking the speed of light) will ensure that there will not be a lot of brain matter left after arriving.

Yes; I know you meant 3 days. But that wouldn't make it nearly as funny.  

Technically 3 seconds to Mars from the crews perspective is still within the realm of plausible physics. The crew would only experience the first milisecond, however, because they'd be dead after that.

[legoclone09]

On 3/28/2016 at 10:19 AM, fredinno said:

Yeah... You're probably better off putting living beings in particle accelerators.

Large Human Collider? Yes.

[SR]

On ‎26‎/‎03‎/‎2016 at 2:54 AM, ImmaStegosaurus! said:

I have ran into claims that new witchcraft engines could get us to Mars in three seconds*.

Getting to Mars in 3 seconds is possible. You either:

A: develop FTL propulsion

B: move Mars/Earth (Mars would be easier due to lower Mass.)

[Monsterlunch]

How to travel to Mars in 3 seconds:

Step 1: Create a local gravitational field not affecting anything but your spacecraft orbiting around it.

Step 2: Send your spacecraft to mars using conventional propulsion.

Step 3: Un-create the gravitational field

Due to the habit of gravitational fields bending space-time, time passing for our admittedly VERY brave astronauts could be reduced to three seconds without actually violating the laws of physics. Just have to get around the problem of our gravitational field swallowing planets and stuff...