Ancient workers used clay bricks to make grain silos more than 10 meters high. With gravity 1/2000 a structure made with equivalent material can be built to the Lagrange points.
Dr. Martin Lades has now solved the longstanding MSE problem of Phobos/tether collision. His numerical analysis of an off-equator tether has determined that a reasonable tether design can passively avoid Phobos. In one example, an MSE base station just 13 degrees off the equator has a tether curve that clears Phobos. No active tether management is required.Our Omaha Trail press release here.
Quote from: LMT on 09/24/2017 01:36 pmDr. Martin Lades has now solved the longstanding MSE problem of Phobos/tether collision. His numerical analysis of an off-equator tether has determined that a reasonable tether design can passively avoid Phobos. In one example, an MSE base station just 13 degrees off the equator has a tether curve that clears Phobos. No active tether management is required.Our Omaha Trail press release here.Off-axis elevators are certainly an interesting solution and provide continuous ops, rather than a two step Deimos/Phobos tether pair with central coast phase.The coilgun launcher above Deimos near Deimos L2 is not very clear in this design, nor are the advantages relative to just jumping off the counterweight at the appropriate time. Guess we have to wait for the full paper/presentation?
Ah, firing the Deimos coilgun inward as a lead-in boost for a conventional oberth maneuver departure burn then, didn't catch that.
The structural arrangement baseline for the coilgun relative to the L2 tether would be interesting to see, along with the Deimos L1 dock arrangement considering the no capstan rule.
Very interesting - just one minor point. The 'Taylor Oner' you credit with the Deimos image is really Tayfun Oner.
Quote from: stefan r on 08/14/2017 09:10 pmAncient workers used clay bricks to make grain silos more than 10 meters high. With gravity 1/2000 a structure made with equivalent material can be built to the Lagrange points.{laughs} That's a hilarious image.An unfired, hand pressed clay brick has a crush strength of around 15kg/mē and a course height of around 100mm. At Phobos surface gravity (but completely ignoring the reduction of gravity with height) that lets you build a structure 170km tall. Which is way beyond the Phobos/Mars L1 point.On Phobos, you can build a brick staircase to orbit.
Integrating new SpaceX spacecraft into the Omaha Trail: quantifying efficiencies and radiation protection, in conference at the British Interplanetary Society.Press release Nov. 7.Dr. Lades presented new Mars Lift feasibility details, plus our estimates of Omaha Trail efficiency and radiation shielding for new (2017) SpaceX designs. Highlights:- Number of Earth launches for cargo cut 71%.- Number of Earth launches for crew cut 83%.- Solar flare proton flux cut 90%+, eliminating dedicated solar flare shelter....Omaha Trail, crew flight staging. Deimos propellant and water shielding.
First of all, the benefits aren't even real benefits. There is no "dedicated solar flare shelter" because SpaceX is just using the supplies that would be onboard anyway as shielding.
You aren't particularly clear on how you cut proton flux by 90%, but that would basically involve heavy shielding everywhere, wasting much of the carrying capacity.
Your reduction in Earth launches is pointless, because the Earth launches are relatively cheap, you are ignoring the costs of getting those extra ships you are using as tankers there to start with
it does not seem like your propellant amounts would work out
Quote from: meberbs on 11/12/2017 06:03 pmFirst of all, the benefits aren't even real benefits. There is no "dedicated solar flare shelter" because SpaceX is just using the supplies that would be onboard anyway as shielding.? No, absent additional shielding a dedicated shelter space is needed. Hence the R&D of SR2S, etc. Likewise Omaha Trail shielding. That's why SpaceX included a dedicated shelter space in the new spacecraft design. Why did you think otherwise?
Quote from: meberbs on 11/12/2017 06:03 pmYou aren't particularly clear on how you cut proton flux by 90%, but that would basically involve heavy shielding everywhere, wasting much of the carrying capacity.It's a 130-ton water shield from Deimos. What's unclear? As for "carrying capacity", ascent cargo payload limit applies during ascent. It has no bearing in transit.
Quote from: meberbs on 11/12/2017 06:03 pmYour reduction in Earth launches is pointless, because the Earth launches are relatively cheap, you are ignoring the costs of getting those extra ships you are using as tankers there to start withExtra ships? No, fewer because less propellant is used. Also it's far cheaper to build and operate a fleet of, say, 25 giant boosters than a fleet of 100. That itself is justification, though of course the Omaha Trail would offer other benefits.
Quote from: meberbs on 11/12/2017 06:03 pmit does not seem like your propellant amounts would work outDid you calculate something? With Omaha Trail facilities, the numbers add up.
Solar storm shelter is not a dedicated area, and the shielding comes from supplies that are carried anyway. Try actually reading my post before you respond next time.
You clearly have not actually understood SpaceX's plans. Their fleet of boosters will probably be < 10
You should go research the rocket equation
I calculated something. Assuming you somehow have 3 ships leave Deimos starting with full fuel Lets call this amount of fuel 3. They will spend some amount of fuel that we can call X departing for Earth and then capturing at Earth. You then have a total of 3-X fuel. Unfortunately to send 3 ships back to Mars from LEO (without the excess weight from your unnecessary radiation shield), you need a total fuel of 3 full ships. Since 3-X < 3 you do not have enough fuel.
Quote from: meberbs on 11/13/2017 03:02 amSolar storm shelter is not a dedicated area, and the shielding comes from supplies that are carried anyway. Try actually reading my post before you respond next time.It's dedicated. Musk said as much. It's "a small part of the ship," and noted in presentation.
Quote from: meberbs on 11/13/2017 03:02 amYou clearly have not actually understood SpaceX's plans. Their fleet of boosters will probably be < 10Booster ratio is invariant. Musk's intention (2016) was "1,000 or more spaceships" per window. With 2017 resizing that payload needs ~2,000 ships and ~12,000 booster launches. A single-digit fleet couldn't do that. Did Musk explicitly abandon the intention? I hadn't heard.
Quote from: meberbs on 11/13/2017 03:02 amYou should go research the rocket equationNo, that's wrong and inappropriate.
Quote from: meberbs on 11/13/2017 03:02 amI calculated something. Assuming you somehow have 3 ships leave Deimos starting with full fuel Lets call this amount of fuel 3. They will spend some amount of fuel that we can call X departing for Earth and then capturing at Earth. You then have a total of 3-X fuel. Unfortunately to send 3 ships back to Mars from LEO (without the excess weight from your unnecessary radiation shield), you need a total fuel of 3 full ships. Since 3-X < 3 you do not have enough fuel.That's not the rocket equation.Cutting [X], that's kinda what Omaha Trail facilities are intended for. Maybe you can find improvements.
Wait, you are saying the rocket equation is wrong? No seriously, the rocket equation states that contrary to your previous post, the mass of what you are trying to move matters a lot for on orbit maneuvers. It is not a hard equation to understand if you bother to look it up.
Quote from: meberbs on 11/13/2017 03:02 amWait, you are saying the rocket equation is wrong? No seriously, the rocket equation states that contrary to your previous post, the mass of what you are trying to move matters a lot for on orbit maneuvers. It is not a hard equation to understand if you bother to look it up.No, telling people to "look it up" is wrong and inappropriate. And you're not using it yourself. You should use it.
As for "carrying capacity", ascent cargo payload limit applies during ascent. It has no bearing in transit.
Quote from: LMT on 11/13/2017 12:18 pmQuote from: meberbs on 11/13/2017 03:02 amWait, you are saying the rocket equation is wrong? No seriously, the rocket equation states that contrary to your previous post, the mass of what you are trying to move matters a lot for on orbit maneuvers. It is not a hard equation to understand if you bother to look it up.No, telling people to "look it up" is wrong and inappropriate. And you're not using it yourself. You should use it.The only thing inappropriate is that you are trying to propose changes to an architecture created by experienced engineers when you apparently don't understand the most basic of equations governing rockets, and that you refuse to even do basic research on your own. I am using the rocket equation in the very post that you quoted. I draw a very basic conclusion from it that you previously denied:Quote from: LMT on 11/13/2017 12:48 amAs for "carrying capacity", ascent cargo payload limit applies during ascent. It has no bearing in transit.Which is wrong, because the cargo mass has a major impact on available delta V.
Quote from: meberbs on 11/13/2017 02:46 pmQuote from: LMT on 11/13/2017 12:18 pmQuote from: meberbs on 11/13/2017 03:02 amWait, you are saying the rocket equation is wrong? No seriously, the rocket equation states that contrary to your previous post, the mass of what you are trying to move matters a lot for on orbit maneuvers. It is not a hard equation to understand if you bother to look it up.No, telling people to "look it up" is wrong and inappropriate. And you're not using it yourself. You should use it.The only thing inappropriate is that you are trying to propose changes to an architecture created by experienced engineers when you apparently don't understand the most basic of equations governing rockets, and that you refuse to even do basic research on your own. I am using the rocket equation in the very post that you quoted. I draw a very basic conclusion from it that you previously denied:Quote from: LMT on 11/13/2017 12:48 amAs for "carrying capacity", ascent cargo payload limit applies during ascent. It has no bearing in transit.Which is wrong, because the cargo mass has a major impact on available delta V.That's a confused post. Calculate some particular delta-v, flare shielding, or other quantity you imagine contentious, and try a comparison.
You are the one who seems to be confused.
you apparently don't understand the most basic of equations governing rockets, and that you refuse to even do basic research on your own