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#1 Yesterday 21:02:10
- tahanson43206
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- Registered: 2018-04-27
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15 Days to Mars - Any Propulsion Method
In another topic in this category, PhotonBytes introduced a topic with the intriguing goal of showing that it might be possible to move a payload between Earth and Mars in 15 days, using chemical fuel. That proposition is certainly interesting and I am hoping that our members will study the idea to see if it is permitted by the Real Universe.
However, the basic idea, of a 15 day transit from Earth to Mars in 15 days would appear to be permitted in the Real Universe.
This topic is offered for NewMars members who would like to show us how it might be done.
The conditions to be met, for a demonstration of feasibility, are going to be reasonable.
We will start from LEO, and consider the flight a success when the vessel is safely in LMO.
To make the exercise realistic, I will specify that the payload to be delivered to LMO is 100 metric tons.
The mass of the vessel when it arrives at LMO is up to the contributor, but it needs to be reasonable/plausible.
The time frame for this flight is 15 days, from LEO to LMO.
Because Mars and Earth are varying distances apart, I'll provide a specific distance to be covered as 120,000,000 km.
Mars is 121,047,586 km away from Earth at 3:23:02 UTC on 2025/02/22. The two planets approached each other as close as they will get a week or two ago, in this cycle.
My guess is that there exists no technology able to perform this feat at present.
However, it should be possible for someone to work out the energies required, and to speculate on how a future technology might work.
It would be helpful if contributions were shown to adhere to the physics we can all agree upon.
This could be a very interesting topic for future readers, if our members have the time and energy to invest.
An optional detail that would be welcome is the G force to be experienced by the vessel during the flight.
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#2 Yesterday 21:07:03
- tahanson43206
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- Registered: 2018-04-27
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Re: 15 Days to Mars - Any Propulsion Method
This post is reserved for an index to posts that may be contributed by NewMars members over time.
It would help me greatly to update the index, if our contributors were to include a one line summary of the post. This is the first time I have asked for help with the index idea, but I am finding it difficult to keep up with our members as they add new content to the topics where index posts are present.
After you have submitted your post, please look it over and decide what it was about. You can edit that summary at the bottom of the post, and I will do my best to try to copy it to the index within a day.
Index:
Post #3: https://newmars.com/forums/viewtopic.ph … 22#p229922
GW Johnson - preliminary sketches and text for 15 day flight Earth-Mars
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#3 Yesterday 21:49:52
- tahanson43206
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- Registered: 2018-04-27
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Re: 15 Days to Mars - Any Propulsion Method
This post contains content delivered by email.
GW Johnson took an interest in the problem posed by PhotonBytes, and has agreed to participate in the new "Any Method" topic.
There are two images that go with the text below, which I will add as soon as possible (which might be Saturday)
Well, I simply used the data worksheet in the orbits+ course orbits spreadsheet to look up the average distances and speeds of Earth and Mars. To fly a short trip, the limit is straight radial. So I used a straight radial shot at constant speed, lasting 15 days per PhotonBytes, to find the necessary departure and arrival speeds.
To go straight radial, you have to kill Earth's orbital speed while you accelerate to your necessary radial speed. To arrive, you have to kill all that radial speed, but you must also acquire the orbital speed of Mars. The necessary vector speed changes are easy to figure, since these are right triangles. It's Pythagorean Theorem stuff.
Summing the departure and arrival, you are looking at something on the order of 133-134 km/s dV out of your vehicle, for the one-way trip. And that ignores going into orbit or landing. Those would be small additions. to the dV, in comparison. Further, these are impulsive velocity changes, requiring rather significant thrust/Earth-weight ratios out of your propulsion and vehicle designs. See the first png sketch "short trips to Mars.png".
<snip unrelated commentary>
Propulsion for Fast Trip
Image 1 goes here:
15 Day Flight Plan to Mars
Image 2 goes here;
I am hoping other NewMars members will feel empowered to participate. What I'm looking for are guesses about the technology that would make such a flight as this not only possible, but practical and economically justifiable. I expect that in 100 years, if the human race manages to survive that long, power in the required range will be available to the average person, just as a team of 100 to 400 horses is available to the average person in the United States right now.
As PhotonBytes has shown, it is possible to enlist the aid of computer aided software, but each participant is responsible for the accuracy of the results posted.
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