15 days to Mars: Chemical Rockets

PhotonBytes · Yesterday 20:36:28

UPDATE: Proabably need 4 total starships, with 3 as tankers to get 13km/s for 15 days transit. 2 Starships only gets us 10km/s which is 3km/s shy of required deltaV. Original 2 ship idea could probably get us closer to 28 days.

Numbers:
https://docs.google.com/spreadsheets/d/ … sp=sharing
https://www.exploremars.org/wp-content/ … ectory.pdf

By using 2 X Starship rockets fully fueled in Low Earth orbit we can boost deltaV from 6 to 9km/s, enough for conjunction orbital transfer. One Starship is crewed and the other uncrewed. The uncrewed one either is attached to the crewed or just flies in a parallel vector nearby at a safe distance. One both rockets are at half tank, the uncrewed transfers all it's fuel to the crewed one and is abandoned. The crewed with full fuel tank continues on it's journey using Conjunction Orbital Transfer. There is now a total delta V of 9km/s enough to slow down with rockets without risky aerobraking manuvers.

Original Article in link below:
https://photonbytes.com/2025/02/21/15-days-to-mars/

Last edited by PhotonBytes (Today 01:01:02)

tahanson43206 · Yesterday 21:29:57

This post is reserved for an index to posts that may be contributed by NewMars members over time.

Among the posts that I hope someone will contribute is a definition of the term "conjunction" in this context.

Update: it seems to me there may be educational opportunities for NewMars members, as we attempt to understand this new topic.

We have seen that the ideas of Void occasionally lead to useful results, after NewMars members have time to consider them carefully.

This new topic may be an example of that.

(th)

PhotonBytes · Today 01:03:09

I've updated the original post but here is the main thing: 2 rockets gets us to 10km/s which is 25 days transfer. To get the speedy 2 week 14 days transfer need 2 more rockets, check original post for details or just read the screenshot below.

Google Spreadsheet showing the numbers here:
https://docs.google.com/spreadsheets/d/ … drive_link

Last edited by PhotonBytes (Today 01:04:38)

Void · Today 09:30:02

PhotonBytes,

It is my opinion that your idea(s) fall within a description of "Multi-staging from Microgravity". I am very happy to see you looking into this.

Of course, in the end the math is life and death in importance. But along with that, an evaluation of purpose, options, and philosophy, matter.

In this case, it is assumed that the start is in microgravity in LEO, for the most part.

Some of what I say is what I think I have absorbed from other people to some extent, I hope, Dr. Zubrin as one.

In pushing the envelope, the idea of reuse, is not always the only reasonable option. Reuse is important for $$$ for the most part. But could be a wrong obsession, at times as it may not be the best $$$. And only caring about $$$ may interfere with an ultimate success goal at times.

Speed to Mars would be valuable if we supposed that what we sent there, would benefit by less exposure to deep space. The Martian environment may be better than deep space, so it might have merit to get there fast.

But then can the thing sent to Mars, be given life support there. Can a method of return to Earth exist as an option?

I do like the multi-staging options. For fast, as you have suggested you could turn two Starships into Drop Tanks. Remove the nose assembly in LEO and maybe reduce the number of engines. So, then drop the drop tanks when it is sensible to do so.

A different option would be to work with the 2-year free return option that I think Dr. Zubrin has suggested. In that case the 2 booster Starships could be outfitted additionally with electric rocket propulsion of some kind. So, as you approached Mars, they would drop off and fly back to an Earth encounter of some kind.

But the ship they supported would then attempt an encounter with Mars, either to go to orbit or to land directly on Mars.

So, then then two booster Starships would then take 2 years more or less to get back to either an orbit of Earth or a landing.

Many factors may contribute to an evaluation of relative value in these ideas. For one thing, has robotics reduced the price of a new Starship so much that it is not deemed worthwhile to retrieve a Starship from deep space after 2 years? Or is it better to discard them as drop tanks?

Reuse is in many cases the best path to $$$ but not always. And the future suggests almost infinite labor resources on Earth and perhaps other worlds.

Ending Pending

Oh! I think that a 2 year "Free Return" for two boosters then requires a 6 month trip to Mars from Earth.

Ending Pending

Last edited by Void (Today 09:48:58)

PhotonBytes · Today 10:37:16

Yes I think it's worth planning a way to recover the expended "fuel tankers". Could equip them with an ion/plasma/VSMIR drive or maybe let them enter Martian Orbit but take longer to do so and they can do the aerobraking thing too but over a much longer time vs the crewed ship. Or like you said, let them return to Earth over a much longer time period. Probably just to LEO and let them get refurbished in orbit and then refueled for yet another mission. Like the first stage Heavy Booster but in orbit instead of on the surface.

Void wrote:

PhotonBytes,
It is my opinion that your idea(s) fall within a description of "Multi-staging from Microgravity". I am very happy to see you looking into this.
Of course, in the end the math is life and death in importance. But along with that, an evaluation of purpose, options, and philosophy, matter.
In this case, it is assumed that the start is in microgravity in LEO, for the most part.
Some of what I say is what I think I have absorbed from other people to some extent, I hope, Dr. Zubrin as one.
In pushing the envelope, the idea of reuse, is not always the only reasonable option. Reuse is important for $$$ for the most part. But could be a wrong obsession, at times as it may not be the best $$$. And only caring about $$$ may interfere with an ultimate success goal at times.
Speed to Mars would be valuable if we supposed that what we sent there, would benefit by less exposure to deep space. The Martian environment may be better than deep space, so it might have merit to get there fast.
But then can the thing sent to Mars, be given life support there. Can a method of return to Earth exist as an option?
I do like the multi-staging options. For fast, as you have suggested you could turn two Starships into Drop Tanks. Remove the nose assembly in LEO and maybe reduce the number of engines. So, then drop the drop tanks when it is sensible to do so.
A different option would be to work with the 2-year free return option that I think Dr. Zubrin has suggested. In that case the 2 booster Starships could be outfitted additionally with electric rocket propulsion of some kind. So, as you approached Mars, they would drop off and fly back to an Earth encounter of some kind.
But the ship they supported would then attempt an encounter with Mars, either to go to orbit or to land directly on Mars.
So, then then two booster Starships would then take 2 years more or less to get back to either an orbit of Earth or a landing.
Many factors may contribute to an evaluation of relative value in these ideas. For one thing, has robotics reduced the price of a new Starship so much that it is not deemed worthwhile to retrieve a Starship from deep space after 2 years? Or is it better to discard them as drop tanks?
Reuse is in many cases the best path to $$$ but not always. And the future suggests almost infinite labor resources on Earth and perhaps other worlds.
Ending Pending
Oh! I think that a 2 year "Free Return" for two boosters then requires a 6 month trip to Mars from Earth.
Ending Pending

Last edited by PhotonBytes (Today 10:38:54)

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15 days to Mars: Chemical Rockets

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