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One of the problems is lack of knowledge. Most asteroid data pages give wild guesstimates of a size range for various asteroids. They can measure the asteroid's magnitude (brightness) and then give one estimate if the asteroid is dark (low albedo) and another if it reflects a lot of light (high albedo).
The WISE mission may gives us more info on asteroids
http://wise.ssl.berkeley.edu/]http://wi … keley.edu/
Hopefully it will tell us the size of each asteroid. Given an asteroid's size and magnitude, it's albedo can be inferred.
Once the albedo is known, good guesses can be made if a particular asteroid is metallic, stoney, carbonaceous chondrite, etc.
I believe this will be a very large step towards making exploitation of NEO resources possible.
Here is a nice close carbonaceous chondrite:
http://antwrp.gsfc.nasa.gov/apod/ap0209 … 20919.html
1998 KY26
has 0.984 AU perihelion, 1.48 apohelion and a 1.37 year period
http://www.builderau.com.au/program/wor … 322,00.htm
An interesting article noting that a large number of alt-space pioneers made their fortunes with computers and software. It mentions Anousheh Ansari, Paul Allen, Jeff Bezos, Elon Musk and John Carmack.
On this webpage Jim Benson talks about his plans to mine asteroids for propellant:
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Benson enjoys the notoriety from his association with SpaceShipOne, but designing commercial rocket motors only temporarily pays the bills. He's setting his sights much farther into the outer reaches of space to find what he calls "white gold in space"--water.
The idea sounds at once outlandish and startlingly simple. Between Earth and Mars lies an asteroid belt that's much smaller than a similar belt separating Mars from Jupiter. Within the belt, Benson estimates, 20 percent of the particles are dormant comets in which a high percentage of the orbital rocks contain ice under their surface. Benson wants to send a small space miner that can land onto the surface of asteroids and drill a meter into the surface to extract the ice reserves.
What's the significance of ice? Benson believes it will become the rocket fuel for space travel to Mars. His idea is to harness solar power, concentrate its heat, and boil the mined comet ice, powering satellites and space ships with a steam engine. This would let spaceships refuel en route to more distant destinations without lugging up extra reserves.
"I want be the Standard Oil of space," Benson said. "White gold, not black gold. White gold."
We get several comets per year. When will we get a large object flung out of another solar system, or a highly radioactive remnant from a supernova ?
So far as I know, all known objects in our solar system have elliptical orbits (though some are very close to parabolic)
An incoming object with a hyperbolic orbit would be big news.
Brian Marsden usually reports new asteroid or comet discoveries to the community. If I ever did an sf story on visitors from another solar system I would have the ship discovered by NEAT or LINEAR (NEO search programs) and I'd have Marsden report in his very understated, calm manner that the object had a hyperbolic trajectory.
If it fell from outside the solar system, it'll take some delta vee to match velocities with it. At least 12 km/sec if it passes through near earth space. If it's retrograde, that could be up to 72 km/sec.
A planet passing through could be disruptive to the planets, asteroids and comets too. Might cause some problems.
The news article says it'll be a solo flight. But if it carries sandbags with the same mass as two passengers, it would be half the X-prize requirement.
The second half would be doing another flight within 14 days.
14 days after June 21st is . . . July 4.
The thought of them winning the X-prize on the 4th of July makes the hair on the back of my neck stand up.
Travel afar, and never step foot outside. [sigh]
Just another version of the American Vacation. :sleep:
Who said _never_ step outside?
Using telemanipulators to do routine vehicle and hab maintenance may be less costly and dangerous.
This is not a prohibition against humans leaving the habs to do exploration.
I believe telemanipulators would help enable cheap access to space. Without cheap access to space humans may never travel afar.
From an Andrew Nowicki post in sci.space.policy:
NASA is going to use a telemanipulator to replace batteries
and gyroscopes of the Hubble Space Telescope:
http://www.space.com/scienceastronomy/h … 40504.html
Telemanipulator terminology:
http://www.engr.utk.edu/maes/ff/rlk/iee … /rlk/ieee/
Why am I posting this in Human Missions?
Presently orbital assembly is very difficult because pressurized suit gloves have "cucumber fingers", almost useless for most construction work.
Improved telemanipulators would be an extremely useful tool in space development/exploration.
Astronauts on the Moon or Mars would be able to work within their habs and thus avoid opening their airlocks and letting out air as well as letting dust in.
Okay, I'll bite: Whatever made you think that one up??
Maybe he just reread "The Moon Is A Harsh Mistress" by Robert Heinlein.
(snip) And I think it is fitting that they named the probe after one of the most influential and enlightened minds of all time....Constantijin Huygens...
Quite true. And especially so since Huygens discovered Titan.
I believe we would eventually need to bring along some obnoxious critters. Garbage disposal bugs are necessary cogs for an eco-system. Spiders and other predators are useful population controls for the bugs.
I would be surprised if cockroaches didn't manage to stow away and hitch rides to various habs.
Sitting atop an asteroid would provide protection from 2 pi stradians (half the sky). Burrowing would give near complete radiation protection.
Many NEOs are resource rich (water, organic compounds, metals), so NEO mines could help pay the cost of a habitat on an asteroid.
There are 3 possible orbital periods that may be useful for Earth Mars cyclers.
3/2 and 5/4 year orbits are nearly resonant with both Earth and Mars (these orbits are called the Niehoff VISIT 2 and VISIT 1 cycler orbits). Earth rendesvous could be every 3 years or every 5 years. Mars rendesvous could be every 7.5 years or every 3.75 years
2.2 year orbits where the cycler crosses the earth orbit twice approx
2 pi/7 radians apart is the Aldrin cycler. It would rendesvous with earth and Mars every synodic period (about 2 1/7 years)
There are already asteroids that approximate orbits mentioned above.
Here is one: http://clowder.net/hop/2000YJ11.html]ht … 0YJ11.html
Just a reminder: Water, as solar heated steam, would be a great propellant to mine and use to scout amongst the inner asteroids, eh?
I believe nuclear thermal as well as solar thermal engines could use water as reaction mass.
One possible resource in this vein is the asteroid 2001 AV43 which shuttles between near Earth and near Mars.
It's .5 degree inclination is nice (delta vee for plane changes can be steep if inclination is high)
After your post I looked up the orbital elements and drew a pic:
http://www.clowder.net/hop/2001%20AV43. … 20AV43.jpg
It's period is about 1.44 years which is close to 13/9. My spread sheet has this passing through near earth space every 13 years:
2000.98
2013.98
2026.98
etc.
On 2027.98 it passes within 5 degrees of Mars.
(My spreadsheet doesn't take into account perturbations from Earth and Mars. Coming as close as it does to earth, it may lose its 1.44 year period)
It may be possible to change this asteroid's orbit to 1.5 years at an opportune time so that it would visit earth every 3 years and Mars every 7.5 years.
I think asteroid study should be a top goal of NASAs. This goal has two parts.
First, learn about asteroid resources and develop ways to mine and process their resources. This material could be used in space to build things.
Reb, I couldn't agree with you more!
I am hoping Moore's law and continuing miniaturization will enable us to build small but powerful prospector space craft. (If they're small enough, you could send up several in a launch). I envision these craft using ion engines or solar sails.
If small prospector probes are mass produced, the unit cost could be quite low.
If we had a thorough inventory of the resources within easy reach, I believe mankind would be in a much better position to move into space.
What about using the asteroid material to us as a propellent?
Errorist,
Asteroid composition is pretty much unknown. But guesses can be made by studying meteorites and some of the asteroids that have passed by close enough to study.
There are a variety of meteorites. There are very low metal, low water content meteorites called LL if I remember correctly.
There are also carbonaceous chondrites that are from 10 to 20% water in the form of hydrated clays.
There is speculation that many asteroids are extinct comets. Extinct comets are believed to have interiors of water ice protected by an insulating mantle.
If we are lucky enough to find an accessible extinct comet, then this would definitely have materials you could use as propellent. The water could be used as reaction mass or split into hydrogen and oxygen and be used as chemical fuel.
Errorist,
Asteroids worth mining likely will be quite massive. Therefore would be expensive to move into earth orbit. That is why I advocate mining with Kuck Mosquitoes (or using other mining techniques) and sending the mined product to near earth space. These less massive loads are more easily done and would cause much less anxiety than a full blown asteroid approaching our neighborhood.
RobertDyck,
In addition to the common, water rich carbanaceous chondrites, it's believed many NEAs are extinct comets (like asteroid 1979 VA formerly known as Comet Wilson-Harrington). It's thought extinct comets may have water ice beneath their protective insulating mantles.
On this page I have a drawing of small, unmanned craft designed to extract volatiles from from water rich asteroids:
http://clowder.net/hop/railroad/page11. … age11.html
The "Kuck Mosquitoe" is a design by David Kuck of Oracle, Arizona.
Mark Friedenbach,
While it's true the delta vee and transfer time for main belt asteroids are high, there are many near earth asteroids that have near earth perihelions on a regular basis. Often transfer times and delta vee needed to land on such asteroids are small.
Here is a web site of NEAs (2797 of them last time I checked) and their orbital elements:
http://neo.jpl.nasa.gov/cgi-bin/neo_ele … n/neo_elem
You can choose to sort them by orbital period and then hit the "Display Table" button.
This shows 7 asteroids having an orbital period of 1.00 years.
For tiny delta vee if helps to have a near earth perihelion, a semi major axis close to 1 A.U. and a low inclination.
Also helpful is a earth resonant orbit, or else near earth perihelions are very rare events. For example a 1.5 year asteroid with a near earth perihelion will enjoy earth fly-bys every 3 years.
In answer to GCNRevenger's opinion mining asteroids are worthless, many of them have a high water & hydrocarbon content. Depots of water and fuel in near earth orbit would make the solar system beyond low earth orbit much more accessible.
Bolbuyk, here is an asteroid that is already quite close to being a Niehoff VISIT 2 cycler:
http://clowder.net/hop/2000YJ11.html]ht … 0YJ11.html
You will notice a little further down the page is a schedule. The dates are a little weird. 2002.205339 works better in my spread sheet than March 17, 2002. I've colored those events when 2000 YJ11 passes within 10 degrees of Mars or Earth. You can see passes through near Earth space can occur every 3 years and passes through near Mars space every 7.5 years.
Orbital elements are from jpl Horizon ephemeris.
If you'd like to search for other possible cyclers you may go to:
http://neo.jpl.nasa.gov/cgi-bin/neo_ele … n/neo_elem
This page allows you to sort by period so it's easy to find ~1.25 and 1.5 year period asteroids.
Also look for low inclination: High inclination adds delta v and physical distance between asteroids and destination planets.
It's believed a large fraction of asteroids are carbonaceous chondrites which range from 10 to 20% water. I agree with an earlier poster that water is a very valuable resource. It can be used to drink, for radiation shielding, reaction mass with nuclear thermal or solar thermal rocket engines, or its hydrogen and oxygen components can be used for chemical rocket fuel.
It is also suspected that many asteroids are extinct comets (like Wilson Harrington comet/1979 VA asteroid). Extinct comets are believed to have water ice beneath their insulating mantles.
There are 3 cycler orbits I've heard of
Niehoff VISIT 1 has a period of 1.25 years. This can rendesvous with earth every 4 periods or 5 years. 1.25/1.881 = .6646 which is very close to 2/3 of the Mars orbit. It can rendesvous with Mars every third period or 3.75 years. But since .6646 doesn't exactly equal 2/3, there is a drift, 2.2 degrees each rendesvous by my calculations.
Niehoff VISIT 2 has a period of 1.5 years. This can rendesvous with earth every 2 periods or 3 years. 1.5/1.881 = .7976 which is very close to 4/5 of the Mars orbit. It can rendesvous with Mars every fifth period or 7.5 years. But since .7976 doesn't exactly equal 4/5, there is a drift, 4.4 degrees each rendesvous.
Both the Niehoff orbits aren't very far from a Hohmann orbit (1.4174 year period) and the Delta vee isn't very much greater.
The Aldrin orbit is about 2.2 years and intersects earth's orbit in 2 places. After it leaves the descending earth crossing, it miss this crossing 2.2 years later but passes through near earth space at the ascending crossing at a time = 2.1354 years (Mars synodic period) after the first crossing. At that point it uses it's own delta vee plus an earth gravity assist to rotate it's line of apsides. The Aldrin cycler crosses Mars orbit at a substantial angle. Delta vee for Aldrin to Mars shuttles are about 12 km/s. I guess this is considered acceptable because the tiny shuttles would be only a fraction of the cycler's mass.
I thought I had sent a message earlier. Apologies if something like this shows twice.
