mikegarrison

Colonization Discussion Thread (split from SpaceX)

Recommended Posts

5 hours ago, Northstar1989 said:

Polynesian were skilled navigators, but their BOATS could never have survived something like an Atlantic Crossing. 

Nonsense. Really, dear colleague, take a look at the map and the prevailing weather patterns and don't simplify things so much. Experimental archaeology has proven so, though detail questions remain open simply because the art of shipbuilding wasn't traded freely among Polynesians and the ones that where asked last century didn't recall everything too well ;-)

The Polynesian islands are farther apart than the Atlantic is wide. Neither the Pacific nor the Atlantic are "homogeneous" Oceans, an Atlantic crossing in December/January from East to West at 20°N a piece of cake, that's why little girls with GPS and automatic steering can do it in an 8m boat. And several hundred holiday yachts participate in several rallies every year. The way back farther north in autumn spring is more difficult because west wind, cyclones (rain, wind, nothing for the catamaran crews ;-)). Vut that only means that less go east than west. There are cheap boats in the Caribbean for sale ;-)

Of course the navigators knew their weather patterns and when to go where, it doesn't take too much, just a little tradition, to realize.

 

There is no doubt that flexible Polynesian outrigger boats were seaworthy to a degree that they could travel over thousands of miles and did so for several centuries, claiming that they couldn't is simply ignoring reality. Their boats could easily "survive" thousands of miles in the pacific and where out for months, so i cannot understand why you claim that they couldn't.

 

Edited by Green Baron
Confused spring and autumn, silly me ...

Share this post


Link to post
Share on other sites
4 hours ago, Northstar1989 said:

Polynesian were skilled navigators, but their BOATS could never have survived something like an Atlantic Crossing.  They were only able to spread like they did because the islands tgey reached were relatively close together (there's a reason Easter Island, for instance, was isolated from the rest of the Pacific islands- it was much too far for boats built without nails to travel.  There is evidence the first settlers were shipwrecked there or blown off-course by a storm, and unable to return home due to the distance...)

Some of their boats was pretty large, larger than viking ships and stuff, you don't need an large ship to cross oceans but it tend to be safer, you need an large ship to carry lots of cargo. 

Share this post


Link to post
Share on other sites
6 hours ago, Northstar1989 said:

A resupply ship every 6 years for 60 years is NOT "totally self-suffclient from day one", and the numbers I provided were not totally make-up, they were calculated based on the known laws of Compound Interest and the predicted price of a SpaceX ticket to Mars.  Mathematics is a hard science, you CANNOT argue with it, as much as you might like to- only with my (very conservative) assumptions...

My man!

Despite the numbers posted by Elon Musk, Mars will not inherently generate money for a very, very long time for the simple reason that it has no services or products to offer back to Earth beyond scientific research.
Research is a valuable and profitable goal, but it is strongly capped and cannot contribute to the commercial expansion of a human settlement on its own.
I strongly believe that Elon's projects will be funded for a long time by people buying into the project, including himself. If you pay $25000 for a ticket, you're paying for the opportunity to live on Mars - that's the product. What you do once you've landed and been assigned a tent has been unanswered. You have to rely on more people arriving and paying their tickets for the supplies to keep coming. A basic buy-in pyramid scheme unless something gets added to the plan.

Now, pyramid schemes are not an evil thing. They can bootstrap incredible projects that are not viable on day one. They sell hopes, dreams and the future and stay alive on cash injections. However, all schemes fail unless those hopes are realized. The delay between the project beginning and its collapse depends on how many people believe in and pay into Elon's vision. There seems to be a lot of that, so establishing a base and running it for some time might not be an issue.

My view is that the solution to turning this scheme into a valid business is to leverage your 'start-up' capital of humans, equipment and infrastructure on Mars into a profitable industry. That is the true core of the discussion: 

  • What can you do with a few thousand skilled people living on Mars, that people on Earth will pay for?

Share this post


Link to post
Share on other sites

Use them  to get to treasure trove that is asteroid belt? :) Mars is much closer to the belt than Earth is. It's less demanding dV-wise. It does have atmosphere, water, plenty of space for agriculture and semi-decent gravity to let your bones regain some strenght after a year of two  of drilling space rocks.

Share this post


Link to post
Share on other sites
 

Use them  to get to treasure trove that is asteroid belt? :) Mars is much closer to the belt than Earth is. It's less demanding dV-wise. It does have atmosphere, water, plenty of space for agriculture and semi-decent gravity to let your bones regain some strenght after a year of two  of drilling space rocks.

The key to the asteroid belt and most of the inner solar system's small rocky bodies is Mars's moons. Phobos and Deimos are natural propellant depots, with thousands of tons of ice sitting in low gravity, just waiting to be used.
Perhaps a surface installation on Mars can build bulky components like pressure vessels, solar panels and propellant tanks, assemble them with hard-to-make components like rocket engines and avionics shipped in from Earth, and launch them towards Mars's moons to start mining propellants.

The propellants from Phobos and Deimos can then supply spaceships heading towards asteroids at rather low cost. Bringing back metals and ores from the asteroids to Phobos is cheaper than sending it all the way down to Earth and aerobrake to the ground. 

@kerbiloid:

There was also the military aspect. The Space Shuttle could theoretically capture enemy satellites and change orbital inclination unexpectedly using aerobraking maneuvers. It was a bigger, more useful, possibly cheaper replacement to the DynaSoar. Basically, you had a spaceship that could serve the Air Force, NASA and the Army equally well. 

Share this post


Link to post
Share on other sites
 

The key to the asteroid belt and most of the inner solar system's small rocky bodies is Mars's moons. Phobos and Deimos are natural propellant depots, with thousands of tons of ice sitting in low gravity, just waiting to be used.
Perhaps a surface installation on Mars can build bulky components like pressure vessels, solar panels and propellant tanks, assemble them with hard-to-make components like rocket engines and avionics shipped in from Earth, and launch them towards Mars's moons to start mining propellants.

The propellants from Phobos and Deimos can then supply spaceships heading towards asteroids at rather low cost. Bringing back metals and ores from the asteroids to Phobos is cheaper than sending it all the way down to Earth and aerobrake to the ground. 

@kerbiloid:

There was also the military aspect. The Space Shuttle could theoretically capture enemy satellites and change orbital inclination unexpectedly using aerobraking maneuvers. It was a bigger, more useful, possibly cheaper replacement to the DynaSoar. Basically, you had a spaceship that could serve the Air Force, NASA and the Army equally well. 

Then why bother with propellant at all? You could build a network of momentum exchange tethers that regain momentum using ion drives or some other mechanism, and the ship only needs propellant for course corrections and braking at the target ( provided there isn't a catching system). Build a tether network for the Earth-Moon system, use it to eject payloads to Mars and the belt, and then use the payloads to build more tethers at the target. Of course, you have to actually build it first, but we can build a bunch right in our cosmic backyard, and bootstrap our way outwards. Still really expensive, but it may be useful infrastructure for a spacefaring civilization.

Share this post


Link to post
Share on other sites
 

Then why bother with propellant at all? You could build a network of momentum exchange tethers that regain momentum using ion drives or some other mechanism, and the ship only needs propellant for course corrections and braking at the target ( provided there isn't a catching system). Build a tether network for the Earth-Moon system, use it to eject payloads to Mars and the belt, and then use the payloads to build more tethers at the target. Of course, you have to actually build it first, but we can build a bunch right in our cosmic backyard, and bootstrap our way outwards. Still really expensive, but it may be useful infrastructure for a spacefaring civilization.

The scale of investment! 
Putting tethers into orbit large enough to be useful will demand an enormous up-front cost, both in terms of the resources for the tethers themselves, but also the development costs of actually making them work. 

Rocket on the other hand are a well known technology, and mining Phobos is a combination of technologies we are familiar with. Phobos is useful immediately, with even the smallest solar-powered water splitter being useful on its surface. 

The massive benefits of a tether over rocket-powered flight is obvious and they cannot be ignored in the long term. However, it might be better to go with what we know and set up a propellant cycle centered on Phobos, instead of waiting for someone to put the money into tethers.

Share this post


Link to post
Share on other sites
 

Then why bother with propellant at all? You could build a network of momentum exchange tethers that regain momentum using ion drives or some other mechanism, and the ship only needs propellant for course corrections and braking at the target ( provided there isn't a catching system). Build a tether network for the Earth-Moon system, use it to eject payloads to Mars and the belt, and then use the payloads to build more tethers at the target. Of course, you have to actually build it first, but we can build a bunch right in our cosmic backyard, and bootstrap our way outwards. Still really expensive, but it may be useful infrastructure for a spacefaring civilization.

At the risk of getting slightly off topic, it's not nearly as simple as that. The mechanics of orbiting tethers are non-Keplerian, and at best only marginally well understood. But it is known that a tether of any significant length is not going to be following a normal Keplerian orbit, and in most configuration is highly unstable. It's a result of the ends of the tether orbiting at different altitudes, and thus different speeds.

Share this post


Link to post
Share on other sites

This thread was split off from the SpaceX discussion thread, so it's possible that the discussion is a bit disjointed at places.

If you think I forgot your post in the other thread or moved your post here in error, then report it and write why you think it should be moved.

Report this post, if you think this thread should be merged with the Mars colonization thread.

 

Share this post


Link to post
Share on other sites

It's also easy to forget that we landed on the Moon at Apollo 11, not Apollo 1 or Apollo "2". It took five manned missions before the first actual landing. Using Falcon Heavies to assemble Mars vehicles, on the same system, would be a twelve-year ordeal, minimum, just for the first landing. And you'd be looking at 25-30 expendable FH launches.

Edited by sevenperforce

Share this post


Link to post
Share on other sites
10 minutes ago, sevenperforce said:

It's also easy to forget that we landed on the Moon at Apollo 11, not Apollo 1 or Apollo "2". It took five manned missions before the first actual landing. Using Falcon Heavies to assemble Mars vehicles, on the same system, would be a twelve-year ordeal, minimum, just for the first landing. And you'd be looking at 25-30 expendable FH launches.

Well, even 30 expendable FH launches might be cheaper than just 2 SLS launches. Which is kind of silly, if you think about it.

Share this post


Link to post
Share on other sites
4 minutes ago, IncongruousGoat said:

Well, even 30 expendable FH launches might be cheaper than just 2 SLS launches. Which is kind of silly, if you think about it.

Well, yes. But logistically, it's really too much.

Share this post


Link to post
Share on other sites

You can do a Mars mission with just 5 FH launches:

Mars Semi Direct Mars Direct sensitivity to launch capability can be reduced by adoption of Semi-Direct architecture. The Semi-Direct plan involves three payloads. - Mars Ascent Vehicle delivered to surface, w here it makes propellant. - ERV delivered to highly elliptical Mars orbit, with propellant from Earth - Crew flies to Mars in Hab, lands nea r MAV. - Crew explores Mars 1.5 years, then ascends in MAV to ERV - ERV goes on Tran-Ea rth injection. - Crew bails in capsule for Earth Entry. • Mission provides larger ERV than Mars Direct, with less power, - If MAV is kept small, power requirement can be met by either 10 kWe Russian Topaz or by surface solar power Æ eliminates need for new ~100 kWe surface nuclear power system - 2 tonne (LEM size) ascent vehicle adequate for crew of two - Small MAV allows mission with transported methane, Mar tian oxygen. Æ No need for long duration hydrogen storage • Requires Mission-critical MOR on Return leg. • Described at length by Zubrin and Weaver, 1993. Made basis for NASA DRM. • If scaled down to crew of 2, mission should be achievable with three Falcon heavy launches. Mission Sequence Chart Using Dragon for Crew Transportation •Crew of 2 is launched in Dragon capsule •Habitable space is augmented by 8 m long x 6 m diameter inflatable. • Two decks, 56.5 m 2 of floor space, 180 m 3 volume • Artificial gravity enabled by tethering off TMI Stage Cumulative Radiation Doses Received in Space (Scaled from Brookhaven Estimates) The cumulative radiation dose of a human roundtrip mission to Mars using current propulsion technology has already been experienced by numerous astronauts. No radiation-induced health effects have been observed. Logistics for Falcon Mars Semi-Direct mission Falcon Heavy Capability 53 tonnes to LEO 17 tonnes to TMI (H2/O2) 14 tonnes to Mars orbit 11 tonnes to Mars Surface Dra gon mass 8 tonne s Crew Size 2 Payload Ha b ERV MAV Payload Dragon 8000 kg 8000 kg - MAV cabin - - 2000 kg Inflatable cabin 200 kg 200 kg - Food 900 kg 300 kg 20 kg Water 400 kg 150 kg 50 kg Methane - 900 kg 2600 kg Oxygen 100 kg 3150 kg 0 Propulsion System - 400 kg 1170 kg Power System 200 kg 400 kg 1500 kg ISRU System - - 500 kg Other Cargo/margin 1200 kg 500 kg 3160 kg Total 11000 kg 14000 kg 11000 kg •Food = 0.75 kg/person-day = 2100 cal/day for food with average of 2800 cal/kg Peanut butter = 5000 cal/kg, pasta = 3700 cal/kg, pork chops = 2200 cal/kg •Water and oxygen are recycled •With thickness of 0.8 mm, pressure of 5 psi, Kevlar inflatable has 10 X min strength •Inflatable hab is potentially stowable prior to entry, enabling reuse on Mars Development of Mars Base: First Landing First Crew has 2 habs, 2 ERVs, 2 Mars ascent vehicles, 20 kWe, 8 tonnes cargo Dragon serves as airlock for inflatable two-deck surface hab. Development of Mars Base: Third Landing Third Crew has 4 habs, 2 ERVs, 2 Mars ascent vehicles, 40 kWe, 16 tonnes cargo By mission 3, added facilities and availability of Mars water could enable expanded crew

Share this post


Link to post
Share on other sites
1 minute ago, DAL59 said:

You can do a Mars mission with just 5 FH launches:

Stuff

No.

These Dragon based concepts are as goofy as Mars One.

Share this post


Link to post
Share on other sites
9 minutes ago, tater said:

No.

These Dragon based concepts are as goofy as Mars One.

Agreed. Dragon could be used as the ascent vehicle for the astronauts, and/or for the final Earth re-entry vehicle, but anything else is not going to work. Dragon 2 could be made to work for a lunar mission, but not for Mars.

Target orbit rendezvous (separating the landing vehicle from the orbiter) is a no-brainer for lunar missions, due to the dV requirements for powered landing, but Mars is different. The possibility of aerobraking or aerocapture means it's not so simple; if you don't have to bring ANY fuel for Mars capture, a direct ascent approach can mean a lower TLI mass than an Apollo-style architecture. But that means the whole vehicle needs to be in a heat shield, which means orbital assembly is out.

A hydrazine/LOX ascent vehicle with LOX ISRU (cracking atmospheric CO2 into CO+O2) would work well enough, but it has to be done at least three times: once in a small-scale test article, once in a full-scale unmanned ascent test, and finally in the real article.

Share this post


Link to post
Share on other sites
27 minutes ago, tater said:

No.

These Dragon based concepts are as goofy as Mars One.

 

40 minutes ago, DAL59 said:

You can do a Mars mission with just 5 FH launches:

FH is a commercial transport system as it is designed, its not a grocery store for a future Mars mission, at least as it stands BFR is being designed to do that. This discussion is now dragged over several threads and I should remind you that, it could be, but as of yet the most massive and bulky commodity is fuel, and the BFR refueler is not ready anytime soon, so that pretty much ends that discussion.

FH will be improved, thats inevitable but only at a timeframe that the marketplace dictates.
 

Lets at least try to keep the two sets of eggs separated. SpaceX has defined their first attempt. Their best Mars windows are in the 2028 to 2036 for Mars, which should give them enough time to test the BFR system.

Share this post


Link to post
Share on other sites
Just now, tater said:

That pdf is based on Constellation, not FH, how is it relevant?

Scroll to page 15

The first half is on constellation, the second on dragon

Share this post


Link to post
Share on other sites
13 minutes ago, DAL59 said:

Scroll to page 15

The first half is on constellation, the second on dragon

Neither Dragon nor Dragon 2 are viable Mars descent vehicles.

Share this post


Link to post
Share on other sites
1 hour ago, tater said:

That pdf is based on Constellation, not FH, how is it relevant?

I don't understand how this ended up in the SpaceX thread, the Rocket Zubrin defines is more or less a ULA based design (4 SSME), it gives no details on the second stage of the rocket and shows a PL which is larger in diameter than any rocket can currently launch. Then in the midst of the slides he tosses in a Dragon with almost no details on how this would work in his tethered Mars scheme.

Share this post


Link to post
Share on other sites
2 minutes ago, PB666 said:

I don't understand how this ended up in the SpaceX thread, the Rocket Zubrin defines is more or less a ULA based design (4 SSME), it gives no details on the second stage of the rocket and shows a PL which is larger in diameter than any rocket can currently launch. Then in the midst of the slides he tosses in a Dragon with almost no details on how this would work in his tethered Mars scheme.

Skip to page 15 and read from there.

Share this post


Link to post
Share on other sites
16 minutes ago, DAL59 said:

Skip to page 15 and read from there.

I see the slide presentation was from 6 years ago, I see that dragon is not going to Mars or Moon, not even sure if its going to be crew rated, I see that FH is not being directed at Mars exploration. Basically he chose a set of vaporware and speculated about it. The question is why you are presenting this now as if it could happen when Space X says its not going to happen with F9 or FH?

Quote

In a planned in-flight abort test, Dragon will use its launch abort engines to escape from a modified Falcon 9 that is already in flight.[80][81] The launch is planned to occur from SLC-4E.[78] This test will occur at the point of worst-case dynamic loads, which is also when Dragon has the smallest performance margin for separation from its launch vehicle.[80] The Falcon 9 planned to be used will only have three engines on the first stage and will have no second stage.[78]

An uncrewed test mission to the ISS, SpX-DM1, is planned to be launched in April 2018.[82][83] It will be a 30-day mission that will spend the majority of its time docked to the space station.[83] It will then land in the ocean and be retrieved.[83] A crewed test mission to the ISS, SpX-DM2, is planned to be launched in May 2018 and last for 14 days -wikipage SpaceX Dragon

 

Edited by PB666

Share this post


Link to post
Share on other sites
1 hour ago, sevenperforce said:

Neither Dragon nor Dragon 2 are viable Mars descent vehicles.

If you want a reusable lander, you absolutely need a biconic vehicle...but then you need to execute the flip-stall-drop maneuver, which is pretty damn difficult. And you still have to worry about debris impingement.

If you are willing to go expendable, you can use a jettisoned heat shield, but without separate landing engines, you still run the risk of debris damage.

A workable solution is an Apollo-style two-stage lander tucked behind a heat shield, with LOX-hydrazine on both stages. Landing engines, which need only provide impulse from drogue-stabilized terminal velocity to touchdown, can be canted out like the Dragon 2's, and plumbed to the LOX tanks on the ascent stage. The descent stage includes an airlock, solar panels, compressor, and associated systems for ISRU. The heat shield is retained until touchdown, to protect the centrally-mounted ascent engine.

Probably 20-25 tonnes, and needs to be landed at least several months before ascent. Requires, at minimum, one reusable and one expendable Falcon Heavy to put it on TLI (partially-reusable launch to put the vehicle in LEO, and an IDA-only expendable launch mated in LEO for the TLI). If it can be made to fit in the 5-meter fairing.

Edited by sevenperforce

Share this post


Link to post
Share on other sites
This thread is quite old. Please consider starting a new thread rather than reviving this one.

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.