Sunday, October 25, 2015

Space! Heading out there...

First some fascinating news about how seriously some of our leaders in politics and industry are starting to take Our Future In Space.

Shall we begin “bootstrapping” our space technologies toward the goal of a Solar System Civilization? The idea is no longer science fiction alone. “Right now, the mass we use in space all comes from the Earth. We need to break that paradigm so that the mass we use in space comes from space,” said one NASA official – quoted on a page at the site of the White House. 

Yes, the White House. Tom Kalil is Deputy Director for Technology and Innovation at the Office of Science and Technology Policy (OSTP) and his page is a down payment on what might become a special program out of the president’s office, aimed at helping spur the techs we'll need, in order to use space resources.  Look it up… and stay tuned.

Pie-in-the-sky?  Well, the potential methods for extracting space resources are looking more and more manageable, starting with the plentiful water contained in some kinds of asteroids.  Probably the most needed-desirable of all materials in space, and the most expensive need we must fulfill, both for life support and fuel, if humans are to live and work out in space.

Unlike the gold and platinum and iron that our children will relish from rocks out there, water may be accessible much sooner, according to the folks at Planetary Resources and Deep Space Industries.  And TransAstra Corp, where Caltech engineering prof Joel Sercel has worked out a plausible method. In optical mining, thin-film inflatable reflectors and containment bags are used to extract, collect, and store water from asteroids, using concentrated sunlight to crack asteroids and extract the water they contain. Once the water is stored in bags it can be used directly as rocket propellent in a type of engine called a solar thermal rocket. Later solar systems will crack and divide H2O into hydrogen and oxygen, allowing even more effective propulsion and portable power.

== More Space! More Space! ==

Um... At risk of making you all howl over the (utterly deserved and necessary) repetition... have I said already this is our best year in space since the seventies… and possibly ever? 

The roll call of stunning milestones just keeps flowing, with data from Mercury, Venus and Earth… orbiting and mapping Ceres (with its weird white spots and possible underground lakes), tons from Mars (including a comet swooping past the Red planet!), news of a likely Europa mission, wonders from Cassini at Saturn, including amazements from Titan…

…plus landing on a comet!  And of course, New Horizons swooping past Pluto (Watch this beautiful 16 second composite video and remember your civilization did something this competent.)

An article about Pluto Truthers… who claim the New Horizon images are faked, like everything else in the space program.  Eep.

== What more could you want? ==
                                                                                                
Well how about another Mars landing, next year?  InSight (Interior exploration using Seismic Investi­ gations, Geodesy and Heat Transport) is a NASA Discovery Program mission that will place a single geophysical lander on Mars to study its deep inte­rior.

But that’s 2016. Heck we might have a Singularity by then, so let’s stay focused. (Did I elsewhere promise 2014 - 2015 would be transformative?)

Meanwhile, the mavens who gave us spectacular Pluto-Charon images have chosen New Horizons’ next target!  The spacecraft is to make a similar examination of a small, Kuiper Belt object, an icy body known as 2014 MU69 in 2019. Pluto is about three billion miles from the sun; 2014 MU69 is almost a billion miles beyond Pluto. “The New Horizons spacecraft is to adjust course through a series of four thruster firings in late October and early November. New Horizons would also make more distant measurements of 20 other Kuiper belt objects en route to 2014 MU69.”That they can do this at all, with their excellent fuel reserve, is one more checkmark of stunning human competence.  Let’s bring that back into fashion!

Technicians have begun assembling the world's largest radio telescope, with a dish the size of 30 football grounds, deep in the mountains of southwest China's Guizhou Province. Yesterday afternoon, they began to assemble the telescope's reflector, which is 500 meters in diameter, compared to Puerto Rico's Arecibo Observatory, which is 300 meters. "Having a more sensitive telescope, we can receive weaker and more distant radio messages. It will help us to search for intelligent life outside of the galaxy and explore the origins of the universe," Wu Xiangping, director-general of the Chinese Astronomical Society said.

Okay fine. But please read the first few chapters of Liu Cixin’s epic Science Fiction novel (and 2015 Hugo Award winner) The Three Body Problem. That will teach you caution not to press SEND with any “outgoing messages.” Listening is good.

== Other space news? ==

How about a patent on a 20km tall inflated tower from which payloard can be more easily launched into orbit?  This vision from Thoth Technology sounds exciting. Indeed… this is exactly what I described in 1980, in my novel Sundiver. Remember the “Vanilla Needle?” Except that my concept in Sundiver was even grander: an inflated tower that went up past 70,000 feet and was cavernous enough inside so that cargoes would rise up in it using... balloons! 

The Hubble Space Telescope has discovered tiny primordial galaxies, which are estimated to have formed only 600 million years after the universe came into existence.  
                                                                                                         
By now you’ve heard about the discovery of a possibly Earthlike planet orbiting a very sunlike star. And you were wondering… are there aspects of this that I’m not seeing in even the science press?  I wonder what David Brin makes of this!  Did I read your mind? All right, in a nutshell…

… While Kepler-452b is larger than Earth, its 385-day orbit is only 5 percent longer. The planet is 5 percent farther from its parent star Kepler-452 than Earth is from the Sun. Kepler-452 is 6 billion years old, 1.5 billion years older than our sun, has the same temperature, and is 20 percent brighter and has a diameter 10 percent larger.While Kepler-452b is larger than Earth, its 385-day orbit is only 5 percent longer. The planet is 5 percent farther from its parent star Kepler-452 than Earth is from the Sun. Kepler-452 is 6 billion years old, 1.5 billion years older than our sun, has the same temperature, and is 20 percent brighter and has a diameter 10 percent larger. When Earth is that age, it will already be baked by our sun's shifting CUZ or Goldilocks zone. The Kepler 452 CUZ is probably shifting, too.

Astronauts on board the International Space Station (ISS) have tasted space-grown lettuce. The red romaine lettuce leaves were grown entirely by the team and it marks the start of the "veggie project" that will see more food grown in space.

I often mention that I serve on the Board of External Advisers for NASA’s Innovative and Advanced Concepts group… or NIAC… which offers grants for developing far-out-but-plausible concepts for advancing space exploration.  Now see a handy website explaining the criteria used for judging grants!  

A deep astronomical study (the 2015 Space Weather Workshop) found stellar flares on other G-type main sequence stars (of about the same size and rotational period as the Sun) that had far more energy than anything observed by humans coming from the Sun. Combine this with an update on the mysterious "774-775 carbon-14 anomaly," showing that another anomaly happened about the year 993, and the report concludes that superflares 1000 times more energetic than those observed in our historical records of the Sun could be expected to occur about once every 5000 years.  

We need more resilience. 

36 comments:

David Dorais said...

Will be at Seattle's NIAC conference at the EMP Oct 27-29th. See you there? Still sad I can't call it the SFMHOF anymore without quotation marks...retirement can be fun when free stuff like this comes along...

David Brin said...

I'll have to skip the first day and Greg Bear's keynote… I'll be keynoting across town at the VR-AR conference. But see you there!

Laurent Weppe said...

From the previous post:

*"However, there is an extent to which the left does the same thing"

I'm French: unlike the US, where the far-left has been effectively non-existent for decades, we've had a rather prosperous (albeit smaller) network of far-left affinity scams (there's a reason the "Pentagon was struck by a missile, not a plane" canard originated from France), with the added bonus of not-so hidden footbridges between the far-left and far-right scam industries.

***

*"Remember the fungal meningitis outbreak of 2012?"

No I don't remember it: in September 2012 I was in France and rather busy dealing with the aftermath of my mother's unexpected death, so I wasn't very interested in following what was happening on your side of the Pond at the time.

David Brin said...

I never understood what "Pentagon was struck by a missile, not a plane" was intended to signify. Why would that make a difference? Enough to take the risk of a discoverable plot?

Paul SB said...

Laurent,

I'm sorry about your loss. Of course words can do little, especially from strangers, and knowing it's inevitable probably isn't much help, either. Though my father died when I was little, my mother is getting into that grey zone, and I hardly dare to imagine the day.

The meningitis outbreak was an example of how conservative politics leads to body counts. To put it succinctly, it was caused by a pharmacy that cut corners with safety, and because Republicans always favor business interests over public safety, the FDA wasn't allowed to interfere. Here's a link to the Scientific American blog on the subject at that time. I don't have anything more recent.

http://blogs.scientificamerican.com/molecules-to-medicine/elections-have-consequences-fungal-meningitis-and-compounding-pharmacies/

If you are at all a fan of Miyazaki, you might find a recent Studio Ghibli offering interesting. I've always found the arts good ways to help me decompress, though it has been a couple years for you. The movie was not made by the master of that studio, though this student seems to have learned the craft well. It is called "When Marnie Was There." I won't offer any spoilers.

Jumper said...

Well, my hypothesis was that they lit some tires and diesel on fire, added some military smoke, at the Pentagon, and took it down from the inside with a track hoe. A realistic motive would be to immediately throw dirt into the enemy's eyes and provide a held-back bit of evidence to clue them to true vs. false claims of those taking credit. The other motive would be, of course, that the whole deal was theater gone wrong. Or not depending on Cheney + Rumsfeld.
I was truly perplexed by the weirdness I saw in the official story, the photos of parts on the lawn, the security cam video, etc. I suppose all the little discrepancies I noticed were just by chance.
Here's a huge amount of nonsense from the "truthers" of course. Someone saw a puddle of molten metal? Likely lead from uninterruptible power supplies dripped down. The list of nonsense is a mile long. Of course such a string of idiots could be part of the plot to discredit the "truthers." So it never ends.

Paul451 said...

Typos:
"How about a patent on a 20km tall inflated tower from which payloard"

"Paylord" seems ominous.

"CUZ or Goldilocks zone. The Kepler 452 CUZ"

Circumstellar urban zone? Or habitable?

---

Jumper,
"Well, my hypothesis was that they lit some tires and diesel on fire, added some military smoke, at the Pentagon, and took it down from the inside with a track hoe."

While forcing flight 77 to land at a nearby airbase and murdering all the passengers?

raito said...

I'm never quite sure whether I trust people who choose a political party based on their career ambitions (though I fiully realize that, at some level, that's what we all do). Tom chose the Dems because he figured he could go further, faster. On the other hand, he seems to stay bought, and he'd never go against his own interests, so he's somewhat predictable (unless he's playing some long game, which he's done before). He, I, and Tammy Baldwin went to the same high school at the same time. While the rest of us were messing with electronics, computers, and the math team, he was doing debate and figuring out how to convince people of anything (the infamous 'importation of split peas from Botswana' argument).

Jumper said...

Well, I know I'll get chewed on over this, so let me say it's all just devil's advocate stuff and I no more believe it than I would if someone asked me to come up with a believable scenario whereby Santa Claus really existed. Although there are some weird circumstances; I suppose I should know by now that shit happens; unlikely shit, all the time and usually doesn't mean anything.

In any case, "there was no flight 77. It was a manufactured story." ...Heck, I can't even believe that.

Then again, I find it hard to believe Cheney shot a guy in the face by accident.

Jonathan S. said...

"I never understood what "Pentagon was struck by a missile, not a plane" was intended to signify. Why would that make a difference? Enough to take the risk of a discoverable plot?"

Because it's part of the claim that the whole "crashing planes into buildings" thing never happened, that the attacks were all missiles or bombs planted on-site and the planes were all landed elsewhere and all the passengers killed (or given a treatment with one of the mind-wiping devices the CIA got from the aliens at Area 51), all as an excuse to declare war in Iraq. Of course, this all fails to account for multiple eyewitnesses who saw the planes (since initial reports of the first crash in NY mentioned a "twin-engine plane", our local news anchors were speculating about a lost Beechcraft until the second impact), as well as why the Sekrit Shadowy Gubmint would drum up evidence against an Afghanistan-based group if they wanted to attack Iraq, but nobody ever claimed the proponents of these ideas were particularly intelligent or well-educated (or in full contact with consensual reality, for that matter).

Jumper said...

Okay, what exactly is the "infamous 'importation of split peas from Botswana' argument?"

raito said...

Jumper,

Since you asked...

It was something Tom came up with while riding back from a debate tournament. His premise was that (ceasing? it's been years, and since I wasn't a debater, I wasn't there) importation of split peas from Botswana would cause WWIII. The chilling bit was that it was plausible, and all the factual parts checked out.

I'd love it if he was giving an interview somewhere and the interviewer would ask, "So, have your views on the importation of split peas from Botswana changed any?"

Laurent Weppe said...

* "I no more believe it than I would if someone asked me to come up with a believable scenario whereby Santa Claus really existed."

Oh, but Santa Claus definitely existed: it's the whole "built a magical toy factory on the north pole" sequel that's fictional.

***

* "but nobody ever claimed the proponents of these ideas were particularly intelligent or well-educated"

Actually, many adherent to the 9/11 conspiracy theories are well educated, just like you'll get a lot of college-degree holding republican voters who claim to believe that Obama faked his birth certificate.

Conspiracy theories are, by and large, tribal markers used in a perverse signaling game: you despise Cheney, therefore you express your uncompromising loathing by willingly telling colossal lies involving planting bombs in the WTC and throwing missiles at the Pentagon; you despise the Democrats, therefore you express your uncompromising loathing by willingly telling colossal lies involving a fake birth certificate or a massive murder spree by the Clintons; you despise pro-choicers, therefore you express your uncompromising loathing by willingly telling colossal lies involving babies' brains being harvested; you despise Jews, therefore you express your uncompromising loathing by willingly telling colossal lies involving death camps being a "zionist hoax"; you despise Muslims, therefore you express your uncompromising loathing by willingly telling colossal lies involving halal canned meat and bidets being used to brainwash people, etc, etc, etc, etc, etc, etc, etc, etc: the game has an almost endless supply of variations.

And that's why conspiracy theories are so durable as memes: people don't have to genuinely believe the particulars to spread these around.

raito said...

What happens if I loathe them all?

Laurent Weppe said...

"What happens if I loathe them all?"

You become an Objectivist

Deuxglass said...

I was at a meeting of the top floor a week before. A month before that my family and I ate at the restaurant on top. I was talking to a good friend in the second tower when the plane hit. He is no longer with us. About a hundred thousand people saw the second plane crash into the tower. The only emotion I have for these deniers is contempt and hate.

Jumper said...

"About a hundred thousand people saw the second plane crash into the tower"
That's incontrovertible. The really weird people believe in giant mirrors or magic tricks or some story that's so bizarre it makes moon-landing-fakery people look like Einsteins by comparison.

Hollister David said...

Near earth carbonaceous Ivuna asteroids are a possible water source. But their water is in the form of hydrated clays -- difficult to extract.

Also launch windows for accessible near earth asteroids are rare. They can be decades apart. Trip time to a heliocenric rock can easily be the better part of a year.

There are possibliy large quantities of ice at the Lunar poles. Not only water ice but possibly CO2, NH3 and other valuable volatiles. These volatiles in the form of ices are easier to make use of.

It is true that reaching the moon takes more delta V than many near earth asteroids. But the moon has frequent launch opportunities (every two weeks from a given orbit). Trip times are less than a week. If repeated missions are needed to establish propellent mining infrastructure, frequent launch windows and short trip times can accelearation the development time line by several orders of magnitude.

And then there is less light lag latency (~3 seconds). Since signal strength falls with inverse square of distance, lunar bandwidth is much higher. The small light lag latency and high bandwidth makes lunar tele-robots more able than similar robots in heliocentric orbits.

Some argue reaching the lunar poles takes a lot more delta V than reaching the lower lunar latitudes. This is a misconception. Reaching the poles takes only slightly more delta V. What is lost is any-time return. From a given lunar polar orbit, launch windows to earth occur only every two weeks. But any-time return is much less of a need if assets are robotic.

David Brin said...
This comment has been removed by the author.
David Brin said...

MR. Hollister, intelligent argument. Only dig it -- we assume the actual mission to collect small asteroids will be done robotically and hence delta V matters far more than time constraints.

Yes, the notion of hauling a boulder to cislunar space (where the timing is as-you-say better suited to manned operations) may sound nutty… but it seems worth a try. If it works, then asteroids are not just slightly better but lots better. Anyway, we'll learn tons by trying.

In contrast, what do you plan to accomplish at the lunar poles? My graduate adviser predicted the ice there and I participated in early studies. And yes those deposits might be valuable someday… to use ON the moon! There may be enough to later nourish moon bases but little more than that plus a good reserve.

You would use it up hurling it into space? Jiminy. I'm the guy with big (if long range) plans for the moon. In thinking short, you'd jeopardize future generations of Lunies.

Moon water for the moonies!

Jumper said...

"You become an Objectivist"
Thank you for the laugh, Laurent, I needed one. And it was out loud.

Thomas Lee Elifritz said...

Optical mining predates Joel Sercel.

http://lifeform.net/archimedes/Asteroid_Redirect_Mission.pdf

Tony Fisk said...

"I no more believe it than I would if someone asked me to come up with a believable scenario whereby Santa Claus really existed."

Oh, but Santa Claus definitely existed: it's the whole "built a magical toy factory on the north pole" sequel that's fictional.


Following the argument Pratchett laid out in 'Hogsfather', if Santa Claus didn't exist, then the Sun would not rise.

The air pressure at 70,000 feet (~20km) is about 0.1 atm so, in order to maintain a 1 atm pressure at the top, the mass of the column would be exerting about 10 atm at the bottom. A reasonable compromise would be 0.3 atm (~Everest) at the top giving 3 atm at the bottom.

Structurally, that seems quite feasible. The only thing being the risk of giving your passengers the bends (again manageable)

My idea was to park a balloon at 70,000 feet and supply/launch from there. Granted, you don't get the buoyancy/lift the Needle would provide, but you don't have quite the logistics of building/maintaining it, and you don't have to worry about wind shear on a 70,000 foot structure.

Paul SB said...

Tony, I think Laurent was referring to the historical Saint Nicholas, who is buried on an island off the coast of Turkey. I remember seeing a picture of the tomb of Santa Claus in a National Geographic when I was larval, though by that time I had already figured out that Santa was really my Mom. Hogfather was just pointing out the pagan roots of so many of our traditions. Reading it was like a flashback to my ancient history classes in college, though none of my professors had Pratchett's sense of humor. Could be worse, though, we could have inherited Aztec superstitions rather than Celtic and Germanic superstitions.

Paul451 said...

New thread is geopolitical, so...

David,
"we assume the actual mission to collect small asteroids will be done robotically and hence delta V matters far more than time constraints."

However, the distance to the asteroid means that control of those robots is vastly harder. Which means your robot (which is doing a task much harder than any rover ever) is going to be working slow.

That matters.

Because accessible NEOs only have a single suitable low delta-v launch window every decade or so, you need to do survey, mine, and return all within a narrow window of that close approach. In other words, you flash in, dig up, dog out. That's not compatible with slow tech. Additionally, you can't build any infrastructure, so you can't continue to exploit your now-well-mapped resource.

Asteroids with regular synods are generally much further away, with more significant delta-v and time requirements; and, like Mars, they still have a years between launch windows. Likewise, bringing asteroids back to cis-lunar space is not a near-term stepping stone, at least asteroids worth mining for volatiles.

The moon is consistently accessible. The moon can be launched at every two weeks (and returned from at any time.) It can be returned to over and over. One survey and you've got a site mapped for decades. One batch of infrastructure and you've got production until it breaks, or until you've used up the billions of estimated tonnes of ice.

And that's billions. There's plenty for cis-lunar ops as well as for loonies. And indeed, there's likely to be loonies, if we try to access that lunar ice. There's also more likely to be asteroid mining. It's a realistic, near term stepping stone, the first arc of an outward spiral.

--

Laurent,
"Oh, but Santa Claus definitely existed: it's the whole "built a magical toy factory on the north pole" sequel that's fictional."

Sure, but "wealthy Turkish bishop who threw gold coins at prostitutes" is so much less Disney.

Hollister David said...

We've never mined asteroids before, it will be a trial and error process. Even if there weren't trial and error involved, establishing infrastructure would take multiple trips. If launch windows are years apart it could take decades or even the better part of a century to set up a propellent mine. So I believe time as well as delta V must be considered even if the propellent mine is completely robotic.

I favor parking asteroids in lunar orbit. Then they'd enjoy the same frequent launch windows and short trip times as the moon. Also the same short light lag latency and high bandwidth lunar telerobots enjoy. I am one of the very small minority that is enthusiastic about the proposed Asteroid Redirect Mission.

If Paul Spudis' more optimistic projections are correct, there's enough volatiles at the poles to provide propellent for many millennia as well as provide life support to lunar inhabitants. But the existence of these rich lunar ice deposits remains an open question as of this writing.

Duncan Cairncross said...

Paul451
The "small launch window"
Unless my understanding of orbital mechanics is way off what we actually have as a
"Small MOST EFFICIENT launch window"
It is possible to launch at almost any time BUT the amount of DeltaV required goes up

So if you choose to launch at a different time that's OK but for the same launch vehicle you end up with a smaller payload

So for launching to the asteroids you are NOT stuck with years between launch windows - just some dates mean you can use a larger probe

Paul451 said...

Duncan,
" "Small MOST EFFICIENT launch window"
It is possible to launch at almost any time BUT the amount of DeltaV required goes up"


Two points: Not just up, up by a lot. And the rocket equation means that fuel use rises (and payload falls) exponentially with a linear increase in delta-v.

Second: There are a handful of NEOs which require less delta-v to reach than the surface of the moon. Outside of those windows, they require more delta-v than the surface of Mars. If you want to argue (as asteroid advocates do) that delta-v to the asteroids is less than to the moon because of these NEOs, you have to accept the limits of the narrow launch windows and long delays between launch windows for NEOs. Terms swing quickly in favour of the moon. (If it wasn't for the apparently abundant volatiles, that wouldn't matter. But they are, so it does.)

Hollister David said...

The Keck Report suggests parking an NEO in a retrograde lunar orbit. This can be accomplished for as little as .17 km/s. It is this report that the A.R.M. mission was originally based on.

High lunar orbits are vulnerable to perturbations from the earth and moon, but less so if the orbit is retrograde. Low lunar orbits are vulnerable to destabilizing tugs from mascons (mass concentrations). I believe there is a sweet spot at 30,000 to 40,000 km above the moon's surface where orbits are long term stable.

It has been proposed that Phobos could serve as a momentum bank for a vertical tether. See my blog post Phobos, Panama Canal of the Inner Solar System

A rock parked in the lunar sweet spot (30,000 to 40,000 km altitude) could act as a momentum bank for a vertical lunar tether. Of course a captured rock wouldn't be as massive as Phobos, but it'd be large enough that the tether's orbit won't be ruined by a catch or throw. If the tether has two-way traffic, up momentum catches/throws can be balanced with down momentum catches/throws and the tether orbit can be maintained with little propellent. Tethers of modest size from this anchor mass could fling to trans earth orbits as well as drop stuff to the moon's surface at a fraction of a kilometer/second.

Not only would such a tether help with the export of mined asteroid commodities, it would also facilitate travel to and from the moon. And I agree with Paul451 that lunar resources will likely play a large role.

Duncan Cairncross said...

Hi Paul

So we have a range - less than Luna to more than Mars,
But it does not "Jump" from less than Luna - it's a progression

That means that the launch window in NOT super short - and even if you choose a badly sub-optimum window it's still doable - especially if you are going to use a high impulse low thrust solution

The other part of the "window" discussion is how many "targets" do you have
Just how many of your NEO's are there?
If you have a one day per year window and 300+ targets.....
Your useful window is effectively - all the time!
Only with repeat missions does the actual single object launch window matter

Hollister David said...

Duncan wrote "Just how many of your NEO's are there?
If you have a one day per year window and 300+ targets.....
Your useful window is effectively - all the time!
Only with repeat missions does the actual single object launch window matter"

To establish infrastructure you will need multiple missions to a single object.

I suppose you could send prospector robots to asteroid A, photovoltaic arrays to asteroid B, fractional distillation apparatus to asteroid C, excavating robots to asteroid D, etc.

But for these various components actually do anything useful, they all need to be sent to the same destination.

Duncan Cairncross said...

Hi David
By the time you get to be actually doing that type of development you will be doing a lot of planning
The planning and development here will simply take the launch windows into account

Paul451 said...

Duncan,
"So we have a range - less than Luna to more than Mars,
But it does not "Jump" from less than Luna - it's a progression"


Errr, no. There's obviously something I'm not getting through. Try this: Do an image search for "porkchop plots". These map delta-v against a range of departure and arrival dates, creating an island of lower delta-v in a sea of unrealistic high delta-v. Notice how small the "island" usually is. With Mars and main-belt asteroids, that island reappears every synod, 2.3yrs for Mars, 3-5yrs for the main belt.

With a low delta-v NEO, the island appears once every decade or two. The delta-v outside that optimal window jumps up to ridiculous levels, such as 20-30km/s, it's not a "progression", it's hitting a cliff.

"Only with repeat missions does the actual single object launch window matter"

Which was my point. If you have to do a survey of the candidate NEOs, then send out your equipment to the chosen NEO, then return your ore, that's three distinct trips in three distinct windows (more if it takes multiple trips to set up the equipment). For a low delta-v NEO, that's 30-60 years until your payload arrives in Earth orbit.

With lunar polar ice, you have a slightly higher delta-v for the initial survey and set-up, but once you are established you are able to continuously mine the site for decades, with trip times measured in days not months, and launch windows of two weeks not two decades. (And once you have a supply of fuel at the other end, delta-v becomes almost irrelevant.)

More importantly, as Hop noted earlier, "water" on sunny asteroids likes NEOs is locked up in clay-like minerals. Energy hungry to release. If the polar craters on the moon contain ice, as the data suggest, then you are just digging up ice.

Duncan Cairncross said...

Hi Paul
I had a look at NEO - porkchops - very revealing

but when I looked at the papers I seem to see a 1 year repeat of the launch windows with a reasonable deltaV (less than 10km/sec)and a longer term better shorter window at about a 10 year repeat

You are right about the long time frames making commercial extraction very difficult,

I would envision using small exploration probes that can use the once a year 10Km/sec mini windows and then launching the extraction/transfer package on the once every ten years window

But your arguments about lunar ice do make sense - I wonder if advances in low thrust high impulse drives will change that

Hollister David said...

10 km/s is a lot of delta V.

From LEO to lunar surface is 6 km/s. From lunar surface back to LEO is about 3 km/s (using aerobraking).

So 10 km/s would be more than enough to go from LEO to the moon and back.

If a NEO's major advantage is delta V lower than the moon's, launch windows are rare.

Extra terrestrial propellent would be a huge game changer. It'd break the exponent in Tsiolkovsky's rocket equation. Carbonaceous Ivunas and the lunar poles are the best candidates for propellent sources. I look at pros and cons in Lunar ice vs NEO ice

Duncan Cairncross said...

Hi David H

Lunar work requires a decent thrust to weight ratio
Asteroid work can use high impulse electric type drives

I don't think any of the electric drives are close to being able to take off in lunar gravity

A high impulse system has nearly 10 times the exhaust velocity of a chemical rocket so 10km/sec in a vacuum with no high thrust requirements may be "easier" than 6Km/sec with a high thrust landing or take-off