Getting to Mars: Is 4 Days Possible?

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Discussion Overview

The discussion revolves around the feasibility of reaching Mars in four days using current or near-future technology. Participants explore the required speeds, acceleration, and the technological barriers associated with such a rapid journey.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant calculates that to reach Mars in four days, a spaceship would need to travel at a constant speed of approximately 580,000 km/h.
  • Another participant suggests a scenario of constant acceleration for two days followed by deceleration for two days, leading to a maximum speed of 1.1 million km/h, but later corrects their acceleration calculation to about 1.8 m/s², which is roughly 0.2g.
  • Concerns are raised about the energy requirements for such speeds, highlighting the need for significant fuel mass, which complicates the mission due to the additional mass requiring more energy to accelerate.
  • Some participants express skepticism about whether current technology can achieve these speeds, questioning if the barriers are primarily financial or technological.
  • Discussion includes the potential of chemical rockets, which may require impractical amounts of fuel, and ion rockets, which lack the necessary thrust for rapid acceleration.
  • Project Orion is mentioned as a possible solution, with some participants debating its viability for interplanetary travel and the associated radiation risks.

Areas of Agreement / Disagreement

Participants generally agree that there are significant technological barriers to achieving a four-day trip to Mars, but there is disagreement on the specifics of these barriers and the feasibility of proposed solutions like Project Orion.

Contextual Notes

Participants express uncertainty regarding the practical application of theoretical designs and the implications of radiation from proposed propulsion methods. The discussion reflects various assumptions about current technology capabilities and the challenges of fuel mass and thrust requirements.

Who May Find This Useful

Individuals interested in space travel, propulsion technology, and the challenges of interplanetary missions may find this discussion relevant.

Anthony Rocco
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I'm having trouble putting my head around this , and i was hoping someone could help me out with this. i heard with our current technology they are saying that it is going to take six months to get to mars. What I want to know is how fast would a spaceship have to be going in order to get there in four days.
 
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Minimum distance to Mars = 56million km
At a constant speed in 4 days = 56million/(24*4) = 580,000 km/h

But assuming you accelerated constantly for 2days and then decelerated for 2days.
You would accelerate at 56million km/172,000s = 324km/s^2 (36,000g)
Reaching a maximum speed, halfway there, of 1.1 million km/h
 
oops thanks astronuc spotted a slight error there.
56million km/(172,000s)^2 = 1.8m/s^2, only about 0.2g

The major difficulty in going fast is the energy needed to accelerate for this long. Which means a lot of fuel which means a lot of mass and so more energy to accelerate the extra mass. You also have to carry enough fuel mass to get back!
 
Is that possible with today's technology? Yes, we haven't done it, but is that a resources and money barrier, or a technological one to such speeds (and also attained with safe levels of acceleration in the case of human passengers)?
 
Researcher X said:
Is that possible with today's technology? Yes, we haven't done it, but is that a resources and money barrier, or a technological one to such speeds (and also attained with safe levels of acceleration in the case of human passengers)?

It's a technological barrier for the following reason.

For chemical rockets, it would take more than the mass of the Solar system in fuel to reach the needed speeds to cross the distance in 4 days. And right now, only chemical rockets can produce the amounts of thrust needed to get things up to speed fast enough.

Ion rockets can reduce the amount of fuel needed to get up to speed, but have such a low thrust, that they would take way too long to get up to speed. (much much more than 4 days.)

We just don't have any present day technology capable of producing enough thrust to keep the acceleration times down, while also keeping the fuel ratio down to a reasonable level.
 
Janus said:
It's a technological barrier for the following reason.
We just don't have any present day technology capable of producing enough thrust to keep the acceleration times down, while also keeping the fuel ratio down to a reasonable level.

How about the spaceship designed by Project Orion, powered by exploding nuclear bombs? That was designed for interstellar as well as cheap interplanetary travel. I'm sure it could muster 0.2g with no problem.
 
I had assumed Orion ships would be ruled out for intra-solar-system travel due to their huge size but, according to Wiki, there are viable designs that are actually too small to be manned, i.e. probes.

That leaves only bathing the Earth/Mars neighbohood in gouts of lethal radiation as a problem.
 
Last edited:
ideasrule said:
How about the spaceship designed by Project Orion, powered by exploding nuclear bombs? That was designed for interstellar as well as cheap interplanetary travel. I'm sure it could muster 0.2g with no problem.
Since I wouldn't say that Project Orion resulted in an actual spaceship design, I'd still consider it a technological barrier.
 

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