Well, the funds were there for the booster, it's just that the request for them was dropped once it became clear the shuttle wouldn't be available in time to carry one up to Skylab (the Skylab rescue flight had already been moved forward from STS-5 to STS-3, maybe even STS-2, by the time of cancelation).
China launches new space station module.
- Thread starter Yminale
- Start date
Well, the funds were there for the booster, it's just that the request for them was dropped once it became clear the shuttle wouldn't be available in time to carry one up to Skylab (the Skylab rescue flight had already been moved forward from STS-5 to STS-3, maybe even STS-2, by the time of cancelation).
True, an asteroid's shallow gravity well can mean less delta V. But delta V (required change in velocity) isn't the only metric.
Other metrics include frequency of launch windows, trip times, and light lag.
Launch windows to a Near Earth Object can be years or even decades apart. Trip times can easily be 6 months.
In contrast, from a given low earth orbit, lunar launch windows open each two weeks. Trip time is less than a week.
Unforeseen problems routinely come up in mining. Autonomous A.I. isn't up to dealing with these. To keep problem solving human minds in the loop, telerobots are a possible solution. The moon's always close, light lag will be around 3 seconds. But with telerobots on a Near Earth Asteroid, reaction time can easily be tens of minutes. The moon's proximity also allows good bandwidth, another factor that favors lunar telerobots.
This depends on the NEO.
One will, of course, choose one with a satisfactory orbit relative to earth - most definitely NOT a distant/fast/etc one with launch windows years or decades apart.
Telerobots?
If you are actually serious about mining asteroids and shipping part of the ore to earth, you won't care about a few extra tonnes.
This means you send humans, not robots.
If you choose an asteroid whose orbit is substantially different than earth's you pay a delta V penalty.
If you choose an asteroid whose orbit is like earth's you have rare launch windows.
Launch windows open each synodic period. Synodic period can be found by (period 1 *period 2) / |(period 1 - period 2)|.
Let's say we have an asteroid with a very earth like orbit whose period is 1.1 years. Earth's orbital period is 1 year, of course.
(1.1 * 1) / (1.1 - 1) = 1.1 / .1 = 11.
So the synodic period will be 11 years.
As a general rule, the lower the delta V, the rarer the launch windows.
Humans in habs (aka canned meat) add enormously to difficulty and expense of a mission.
Given existing paradigms, there's no way mining asteroids could enjoy a return on investment.
You uh, haven't researched the bolded part of your text have you?
Re: Chinal launches new space station module.
Metallic asteroids are thought to come from interiors of differentiated bodies. These have much higher grade metal ores than planetary crusts.
Lunar impacts can be as low as 2.4 km/s, so there is the possibility of intact metallic meteorites in the basins of some lunar craters.
But the most valuable lunar resource is water. There's thought to be sheets of ice two meters thick at the lunar poles.
This potential propellant is quite close to earth orbit as well as EML1 and 2. Much closer than earth's surface.
Propellant exported to earth's orbits could be a profound game changer.
Possible lunar exports to EML1: propellant, water to drink, water for radiation shielding, and air to breathe. If we could load up on these at EML1, manned trips to deep space destinations like NEOs or Mars become much more plausible.
Metallic asteroids are thought to come from interiors of differentiated bodies. These have much higher grade metal ores than planetary crusts.
Lunar impacts can be as low as 2.4 km/s, so there is the possibility of intact metallic meteorites in the basins of some lunar craters.
But the most valuable lunar resource is water. There's thought to be sheets of ice two meters thick at the lunar poles.
This potential propellant is quite close to earth orbit as well as EML1 and 2. Much closer than earth's surface.
Propellant exported to earth's orbits could be a profound game changer.
Possible lunar exports to EML1: propellant, water to drink, water for radiation shielding, and air to breathe. If we could load up on these at EML1, manned trips to deep space destinations like NEOs or Mars become much more plausible.
And yet, you can still find NEOs with very convenient delta vs and launch windows.
For example:
http://en.wikipedia.org/wiki/4660_Nereus
About canned meat - I'm not talking about building an interstellar ship (as in your link), but a stationary O'Neill colony; you can make it as massive as you like without worrying about getting it to move at any velocity.
And this mass should not come from earth - rather, it should come from the asteroids; from earth, you'll only need to lift the mass necessary to keep the miners alive during the trip - so 'a few extra tonnes', sojourner.
Yes, human beings require life support systems - which can be, for the most part (oxygen, centrifugal gravity, etc), artificially/technologically generated - and solar power can provide all the energy you need in the solar system.
They need food, which you have to grow, at least in the long term - again, light from the sun giving you the necessary energy for plant growth.
We already know how to build huge, light mirrors to collect/focus solar light; we call them solar sails.
The only problem we don't know how to solve - as in, it's not, basically, XIX century physics/chemistry - is cheap access to LEO.
And without this, there will be no return on investment - or, rather, you'll have to wait for some time before you receive your return on investment (until slow moving shipments of ore reach earth).
It should be noted, though, that there are many proposals on how to overcome this problem - and many are very convincing.
low Earth orbit
If you call launch windows every 2.2 years convenient.
Before making pronouncements on that link, I suggest you read it.
Only the first part of it is devoted to interstellar travel. He starts talking about our own solar system fairly early on.
It would take massive, MASSIVE mining and manufacturing infrastructure to convert an asteroid to an O'Neill cylinder.
Until that infrastructure is in place, human habs and consumables would have to be imported from earth. And, no, it wouldn't be just a few tonnes.
I do, indeed.
Commercial/exploratory expeditions used to take much longer.
Work contracts are made for much longer periods.
The size of the O'Neill colony depends directly on the number of supported people.
A few tens/hundreds of people are sufficient for the first stages - mining, establishing an infrastructure.
This workforce, in time, will grow and build the massive O'Neill colony we are thinking about, with native materials.
Needless to say, the O'Neill colony for these tens/hundreds will be... unimpressive, as size goes; unlike its potential.
In part, true - you'll have to import from earth the 'initial investment' necessary in every business, consisting of:
-a few tens of people
-life support for a few tens of people, until a solar energy generator is built; from then on, only food, until a small O'Neill colony is built.
-the initial mining/industrial machines - which will, at some point - soon enough - make larger copies of themselves.
Establishing infrastructure on another body will take multitiple missions. For example, in Spudis and Lavoie's lunar plan 26 missions are launched over 16 years.
Given 2.2 year launch windows, 26 missions would take more like 60 years.
Sustaining such a program through 15 election cycles and past an investor's life span would be hard.
It's instructive to look at Mars Semi Direct. 694 tonnes to LEO. Most of this is to keep 4 people alive for the duration of a single mission. Some of it is power source and infrastructure to use Martian CO2. Extracting life support consumables from an asteroid would take much more elaborate equipment than the Mars ISRU proposed.
Last edited:
ONLY if it loses money.
If it makes a profit after the first decade or so, it will be child's play.
Rome wasn't built in a day. At the beginning, there were only a few backward tribes who started it all.
The same thing can be said about almost every modern major city.
All of them took centuries/millennia to build.
How did these ancestors manage to get past their equivalent of 15 election cycles? By making a living - profiting - from their pioneering work.
The steps from the first mining operations to huge O’Neill colonies promise to take a LOT less than centuries/millennia.
What's the delta v between earth and mars - as opposed to between earth and 4664 nereus?
How much of these 694 tonnes are fuel?
What's the travel time - comparatively?
How much would be built on site - besides fuel for the return trip - as per mars semi direct?
Make no mistake, it will take more than 694 tonnes to LEO to jump start an asteroid mining operation.
But the benefits will be, in the medium and long term, enormous (and I'm talking financially; not even considering 'the future calling' or 'ensuring humanity's survival' or other poetic/inspiring ideas). As opposed to visiting mars for a few months.
I'll say it again. He really hasn't researched that "few extra tonnes" statement. Or how easy it is (not) to setup a large space habitat.
And sounds like your mining operations would be consuming most of the ore to build the habitats for the mining operations. Which would be redundant if your goal is to mine ore to return to earth.
And sounds like your mining operations would be consuming most of the ore to build the habitats for the mining operations. Which would be redundant if your goal is to mine ore to return to earth.
A small O'Neill colony - large enough for a few tens of people - is necessary for making the miners self-sufficient - as in NOT constantly transporting food/etc to them - and offering them an attractive life-style.
The agricultural area would probably occupy most of the space.
Its mass - perhaps larger than the the mass of the biggest sky-scrapers today - but not by much. And 0g is very advantageous to constructing something.
Actually, working in 0g in space suits is a pain in the ass compared to office tower construction. Have you ever watched EVA's on NASA tv?
Something small enough to only hold "tens" of people doesn't really qualify as an "O'Neil" colony. At that size it's just a space station. O'Neil colonies where known for being large enough to house tens of thousands and were large enough to have their own internal weather.
Something small enough to only hold "tens" of people doesn't really qualify as an "O'Neil" colony. At that size it's just a space station. O'Neil colonies where known for being large enough to house tens of thousands and were large enough to have their own internal weather.
A few.
I've remarked how astronauts were easily moving around objects weighing tonnes - with their mere hands. As opposed to using cranes.
A space station with centrifugal gravity and a LOT more robust than the ISS?
Call it space station, O'Neill colony, etc; it doesn't really matter.
I call it O'Neill colony because it will contain almost all the technologies needed for later, massive colonies.
Apropos these massive O'Neill colonies - as said, Rome wasn't built in a day. But incrementally.
Just setting up an asteroid mine within a lifetime is optimistic.
Actually enjoying a return on investment? That'd probably take centuries.
The Wikipedia article you cited said ~5 km/s for Nereus rendezvous.
Leaving LEO for Mars takes 3.6 km/s. Landing on Mars would take another 6 km/s if there were no atmosphere. However Mars mission designs rely heavily on aerobraking to exit Hohmann transfer and land on Mars. It's thought it would take around 4 km/s to leave LEO and land on Mars.
The Wikipedia article cites this page which cites Shoemaker and Helin's 1978 paper. Shoemaker and Helin base their delta V figure on a Hohmann like orbit to the asteroid's aphelion. (Such an aphelion rendezvous occurs much more rarely than 2.2 years, by the way). Nereus aphelion is about 2 A.U. Trip time would be 11 months, substantially longer than Mars' 8.5 months trip times.
Of course there are much quicker transfer orbits than to Nereus' aphelion. But most of these take more delta V than a lunar landing.
Mars ISRU calls for using Mars' CO2 atmosphere. Lunar ISRU calls for mining ice. Getting water from an carbonaceous chondrite would be tearing water loose from hydrated clays. Like getting water from concrete.
As I said, asteroid ISRU is more challenging than the proposed Mars ISRU.
Here we agree. The potential for asteroidal resources is enormous.
However, if everything were launched from the bottom of earth's gravity well, the ~13 km/s hurdle would preclude enjoying a profit and the scheme becomes a non-starter.
But if we had a supply and staging platform at EML1, mining asteroids becomes more plausible. That is one of the main reasons I'd like to see lunar infrastructure - it'd enable NEO exploitation.
I have little interest in Mars. I just cited Mars Indirect to demonstrate humans and their life support take a lot more than a few extra tonnes.
Last edited:
