How SpaceX Plans to Land the First Humans on Mars

[Truthseeker007]

Anybody know off hand how long it will take to fly to Mars?

 

[rod]

Anybody know off hand how long it will take to fly to Mars?

Good question. This morning, Earth and Mars are separated by some 2.2 AU distance, Starry Night Pro Plus 8 and Stellarium 0.19.3 ephemeris computation. Using 2 AU distance and traveling at constant velocity of 15 km/s, the trip could take a bit longer than 231 earth days. So NASA needs to prepare well for a trip to Mars

 

[Mental Avenger]

The only feasible path between Earth and Mars is a Hohmann Transfer Orbit, which is a LOT longer than the direct distance between. Also, during the journey, the relative positions between the planets changes.
http://jwilson.coe.uga.edu/EMAT6680Fa05/Bacon/hohmanntransfers.html

 

[rod]

The only feasible path between Earth and Mars is a Hohmann Transfer Orbit, which is a LOT longer than the direct distance between. Also, during the journey, the relative positions between the planets changes.
http://jwilson.coe.uga.edu/EMAT6680Fa05/Bacon/hohmanntransfers.html

I see we have another Jedi here JPL has a link too for this type of orbital computation, Let's Go to Mars! Calculating Launch Windows Using the model at the link for students, JPL calculates "The full period of this Hohmann transfer orbit is 517 days. Travel to Mars encompasses half of one orbit, so approximately 259 days."

My 231 days used a quick and dirty method with constant velocity and distance of 2 AU. However, 15 km/s velocity is hot, as fast or faster than New Horizons which initially was close to 16 km/s. I have another text on this too, Fundamentals of Celestial Mechanics by J.M.A. Danby and all the fun calculus

Keep up the good work Jedi Mental Avenger --Rod

 

[Mental Avenger]

I see we have another Jedi here

I don’t know what that means in this context, but I am sure you will explain it.

JPL has a link too for this type of orbital computation, Let's Go to Mars! Calculating Launch Windows Using the model at the link for students, JPL calculates "The full period of this Hohmann transfer orbit is 517 days. Travel to Mars encompasses half of one orbit, so approximately 259 days."

I was posting that for the many people not familiar with the problems involved in interplanetary travel. Many think you just aim your spacecraft at the other planet and blast off. That only works of the planets are not in orbit.

My 231 days used a quick and dirty method with constant velocity and distance of 2 AU. However, 15 km/s velocity is hot, as fast or faster than New Horizons which initially was close to 16 km/s. I have another text on this too,

There is no “quick and dirty method”. Every route between two planets is an orbital transfer of some kind. The efficiency of the flight depends upon the relative positions in the orbits of the two planets. The inefficiency is not just the extra fuel required, but the additional extra fuel required to accelerate the mass of that additional fuel, and the additional extra fuel required to accelerate the extra mass of the spacecraft to hold the extra fuel.

 

[rod]

I don’t know what that means in this context, but I am sure you will explain it.

I was posting that for the many people not familiar with the problems involved in interplanetary travel. Many think you just aim your spacecraft at the other planet and blast off. That only works of the planets are not in orbit.

There is no “quick and dirty method”. Every route between two planets is an orbital transfer of some kind. The efficiency of the flight depends upon the relative positions in the orbits of the two planets. The inefficiency is not just the extra fuel required, but the additional extra fuel required to accelerate the mass of that additional fuel, and the additional extra fuel required to accelerate the extra mass of the spacecraft to hold the extra fuel.

The bottom line upfront. Different elliptical paths from Earth to Mars could be done but the path that uses the least energy is preferred. The JPL link I provided has a simulation showing Earth moving and Mars moving around the Sun, then the intercept course to Mars from Earth using the transfer method, "Though a spacecraft could follow a variety of curved paths from Earth to Mars, one path called the Hohmann transfer orbit uses the least energy and is thereby considered to be the most efficient...Calculating orbit trajectories and launch windows is a complex task involving a variety of parameters that may or may not be constantly changing." ref, the JPL link above.

 

[Truthseeker007]

Good question. This morning, Earth and Mars are separated by some 2.2 AU distance, Starry Night Pro Plus 8 and Stellarium 0.19.3 ephemeris computation. Using 2 AU distance and traveling at constant velocity of 15 km/s, the trip could take a bit longer than 231 earth days. So NASA needs to prepare well for a trip to Mars

Thanks Rod! So pretty close to a year. That is overall not to bad. I know they stay up in the space station pretty long. Yea they don't want to run out of food and water half way there.

 

[Ken Fabian]

These How To "plans" are all too vague to convince me. Optimistic enthusiasm is all very well but some hard nosed pessimism has it's place when talking about giga-USD investments in enterprises that have no income potential apart from, arguably, some video transmission rights. Not many TV shows can reliably earn giga dollars and I fear this one would be a Tragedy.

I remain unconvinced that any Mars colonies will be viable or are even especially desirable. I think there is a variant of Dunning-Kruger at play; ie the more you know the harder it is to remain convinced that it is desirable.

I think that without sound economics underpinning it any colony is in terminal trouble before it begins

I'm more inclined to think SpaceX will successfully achieve better and larger launch vehicles for servicing near Earth requirements and that will be profitable but Mars will remain (as with NASA) aspirational with ongoing but limited spending towards it justifiable as PR/R&D. Elon might achieve a view from orbit and return but I am very doubtful he will achieve any actual colony he can live in.

 

[Mental Avenger]

These How To "plans" are all too vague to convince me. Optimistic enthusiasm is all very well but some hard nosed pessimism has it's place when talking about giga-USD investments in enterprises that have no income potential apart from, arguably, some video transmission rights.

Oh ye of little faith. The fact remains that we do not have any defense against a K-T level impact that could wipe out civilization on Earth. It is vital that we establish viable colonies on Mars. IMO, that will happen before we can develop any reliable defense against asteroids or comets that can impact Earth. While the ROI argument may be sound regarding dollars, it doesn’t come close to the ROI regarding saving humanity. THAT should be the selling point.

I remain unconvinced that any Mars colonies will be viable or are even especially desirable.

We currently have the technology to establish viable, self-reliant colonies on Mars. The only thing currently preventing that is funding.

I'm more inclined to think SpaceX will successfully achieve better and larger launch vehicles for servicing near Earth requirements and that will be profitable but Mars will remain (as with NASA) aspirational with ongoing but limited spending towards it justifiable as PR/R&D. Elon might achieve a view from orbit and return but I am very doubtful he will achieve any actual colony he can live in.

I think you underestimate both SpaceX and the inevitable value of Mars colonies.
BTW, one of those values of Mars will be a manned orbiting outpost between the Asteroid Belt and Earth.

 

[Ken Fabian]

Oh ye of little faith

Mars colonies are in serious trouble if they rely on faith. It is not the faithful that need to be convinced.

The fact remains that we do not have any defense against a K-T level impact

That sounds like a very good reason to develop meteor defenses for Earth but presuming a Mars colony to be achievable but not meteor defense seems premature. Won't Mars need meteor defense also? Mars colonies will be at far greater and more unrelenting risk of extinction level events than Earth.

The Planet B thing sounds good and reasonable as a long term aspiration, at least on the face of it, but attempting to make a colony on Mars does not necessarily follow, especially a colony that I argue cannot survive and thrive on it's own merit.

I have not seen a credible plan for a self reliant Mars colony, just overly optimistic hype. The whole thing fundamentally fails, badly, on finances and economics and that is as critical to success as any technology used. There is no material resource there that can be a basis for trade with Earth and without a way to pay it's way it is reliant on perpetual charity; it's survival will be down to the extraordinary wealth, resources and habitability of Earth, not the untapped resources and potential of Mars.

If Planet B is as inhospitable as Mars is, challenging advanced, comprehensively competent industrial economies to provide the bare minimum forsurvival it is not reasonable to expect it to be able to provide that itself and work as a viable, independent, fully self reliant human society.

I say nothing less than a comprehensively competent industrial economy is adequate for self reliance under such conditions - conditions that make development to that extent extraordinarily difficult. Millions of people, not hundreds are required to achieve true independent survivability sufficient to be the backup population being sought.

 

[Mental Avenger]

Mars colonies are in serious trouble if they rely on faith. It is not the faithful that need to be convinced.

Mars colonies will rely on technology, which we currently have. People like you have no faith in the technology.

That sounds like a very good reason to develop meteor defenses for Earth but presuming a Mars colony to be achievable but not meteor defense seems premature.

Technologically, a system that can defend the Earth from asteroid/comet strikes with 100% certainty would be much more difficult, expensive, and technologically challenging than viable colonies on Mars.

Won't Mars need meteor defense also? Mars colonies will be at far greater and more unrelenting risk of extinction level events than Earth.

That is not true. Colonies on Mars will mostly underground, self contained, and compartmentalized. On Earth, civilization and life as we know it relies 100% on the surface environment, where one K-T level impact anywhere on Earth could wipe out almost all life everywhere on Earth in a few days. A similar impact on Mars would only affect the area immediately surrounding the strike.

I have not seen a credible plan for a self reliant Mars colony, just overly optimistic hype.

Then you have not seen my plans.

The whole thing fundamentally fails, badly, on finances and economics and that is as critical to success as any technology used.

I addressed that with my comment, “The only thing currently preventing that is funding.”

If Planet B is as inhospitable as Mars is, challenging advanced, comprehensively competent industrial economies to provide the bare minimum forsurvival it is not reasonable to expect it to be able to provide that itself and work as a viable, independent, fully self reliant human society.

Again, you have not seen my plans.

Millions of people, not hundreds are required to achieve true independent survivability sufficient to be the backup population being sought.

I disagree. Thousands of colonists could build and maintain viable, self-sufficient colonies on Mars.

 

[Ken Fabian]

Technologically, a system that can defend the Earth from asteroid/comet strikes with 100% certainty would be much more difficult, expensive, and technologically challenging than viable colonies on Mars.

I think we are a long way from declaring Earth a lost cause. Aiming for meteor defense makes sense as a key ambition for developing space capability. It should exist irrespective of ambitions for Mars.

A similar impact on Mars would only affect the area immediately surrounding the strike.

Even for a Mars optimist that is extraordinarily optimistic. I suspect it is also false; a serious KT type meteor strike would make planet wide earthquakes, rain molten rock over the whole planet and destroy crucial infrastructure above and below the surface, including underground habitats.

The only thing currently preventing that is funding.

No, it lacks a credible business plan - one with a bottom line that is in the black. I suggest the lack of any means for the project to recover it's costs is an impediment to finding funding that no amount of optimism can overcome. A potential for profit on investment cannot be demonstrated because it does not exist. Alternatively, as an exercise in charity a Mars "planet B" colony lacks the essential ingredients to get sufficient funding - and competes against already existing bunker options for most credible global catastrophes.

you have not seen my plans

As a thought experiment they may be interesting but a real project of such magnitude needs planning, in detail. I've seen vague and optimistic generalising from Musk but so far no actual plan.

 

[Mental Avenger]

I think we are a long way from declaring Earth a lost cause. Aiming for meteor defense makes sense as a key ambition for developing space capability. It should exist irrespective of ambitions for Mars.

I never said, insinuated, nor suggested “a lost cause”. I pointed out that “a system that can defend the Earth from asteroid/comet strikes with 100% certainty would be much more difficult, expensive, and technologically challenging than viable colonies on Mars.” The corollary to that is that we could establish viable Mars colonies much sooner, even if both projects were run at the same time.

Even for a Mars optimist that is extraordinarily optimistic. I suspect it is also false; a serious KT type meteor strike would make planet wide earthquakes, rain molten rock over the whole planet and destroy crucial infrastructure above and below the surface, including underground habitats.

Not true. A K-T level strike would not cause “planet wide earthquakes”, and it definitely would not “rain molten rock over the whole planet”. That is patently absurd. It was the relatively dense atmosphere of the Earth that carried ash and dust up, held it there, and spread it around the world, and even then the molten rock and debris was fairly localized. Such a strike 200-300 miles from a colony would do very little damage.

No, it lacks a credible business plan - one with a bottom line that is in the black.

Like I said, “The only thing currently preventing that is funding.”

As a thought experiment they may be interesting but a real project of such magnitude needs planning, in detail.

Ok, then apparently you have not seen my proposal for establishing viable self-reliant Mars colonies.