Presented in 2005
Outer space is a dangerous environment for humans to explore. However, unmanned spacecraft, the workhorses of NASA’s current space program, can travel through space with relative ease. By constructing an advanced robotic mining craft using a combination of current and easily obtained future technologies, a mining expedition could be made to one of Earth’s nearest neighbors, a near-Earth asteroid. Near-Earth Asteroids (NEAs) come in all shapes and in all varieties, which makes choosing the proper asteroid to mine a nontrivial affair: considerations must be made of asteroidal orbit, size, and composition. In addition, once the asteroid is reached by the mining craft, the physical and chemical act of mining an asteroid in deep space, far from places where “normal” conditions like gravity and an oxygenated atmosphere prevail, is substantially difficult; each mining implement, procedure, and storage technique must be chosen precisely. After the completion of the first mining mission, the mining craft will return to Earth orbit where it will transfer its precious cargo of ferrous metals, rarer-metals, and volatile gasses to an awaiting orbital station, thus avoiding any further need to launch minerals from Earth, which is extremely expensive. As a result of the asteroid mining and resource gathering operation, the National Aeronautics and Space Association will be able to expand the number of its deep-space operations exponentially.
8. Benefits of Asteroids
Orbiting the Sun
Proximity
Gravity-free
Diverse
Millions upon
millions exist--ready
for the taking
Image source: http://www.calpoly.edu/~rechols/astro101/astro101lab4.html
18. Design Challenge:
Propulsion
Chemical Rocket
Pros: High one-time thrust, proven
Cons: Expensive, bulky
19. Design Challenge:
Propulsion
Chemical Rocket
Pros: High one-time thrust, proven
Cons: Expensive, bulky
Solar Sail
Pros: Inexpensive, uses solar wind
Cons: Low acceleration, untested in space, less
effective farther from the sun.
20. Design Challenge:
Propulsion
Chemical Rocket
Pros: High one-time thrust, proven
Cons: Expensive, bulky
Solar Sail
Pros: Inexpensive, uses solar wind
Cons: Low acceleration, untested in space, less
effective farther from the sun.
Nuclear Thermal Rocket (NTR)
Pros: High multi-use thrust, can used mined
volatiles as fuel, reducing weight.
Cons: Requires the launch of fissionables into
21. Design Challenge:
Propulsion
Chemical Rocket
Pros: High one-time thrust, proven
Cons: Expensive, bulky
Solar Sail
Pros: Inexpensive, uses solar wind
Cons: Low acceleration, untested in space, less
effective farther from the sun.
Nuclear Thermal Rocket (NTR)
Pros: High multi-use thrust, can used mined
volatiles as fuel, reducing weight.
Cons: Requires the launch of fissionables into
22. NTR: TRITON
TRI-modal capable
Thrust Optimized
Nuclear propulsion
Developed by Pratt &
Whitney
Mission-configurable
23. TRITON Modes
Main Thrust
Quick, efficient
interplanetary travel
Low-Power
Power plant for ship
systems and ion drives
Thrust Augmentation
Increase thrust for
heavier loads
24. Main Thrust Mode
CERMET fuel form
Uranium dioxide-
tungsten matrix
Hydrogen is heated as
it passes through the
matrix
Hot hydrogen ejected
produces thrust
Image source: http://rocket.sfo.jaxa.jp/img/le5b1.jpg
26. Thrust Augmentation Mode
Liquid oxygen is
added to hydrogen
ejection system
200% increase in
available thrust.
Similar to a jet
fighter afterburner
27. Design Challenge:
Orbiter
Similar to NEAR-
Shoemaker
CCD camera
Spectrometers
Laser altimeter
Pulsed Inductive
Thruster
28. Design Challenge:
Mining Module
Completely enclosed system
Design eliminates issues:
Zero gravity mineral transportation
Ejecting valuable minerals into space
Powered by TRITON low-power
mode
30. Mineral Separation
Solar arrays heat
vessel to 1,300 K
Electromagnetic
field activated
Gases and metals
separated
Sand dumped
Process repeats
31. Conclusions
Inexpensive space
structures
Orbital Habitats
Science Stations
Interplanetary Rockets
Ad astra per aspera
Notas do Editor
Throughout history, economics has been the premier driving force behind the design, development, and implementation of new technologies. Because space travel is so expensive and, at this time, dangerous, progress made towards exploring and exploiting outer space has been stunted at best.
Launch costs are still extremely high, despite many NASA and corporate attempts to find alternate, cheaper methods of reaching outer space. For a large payload, like that of a space station or interplanetary rocket, upwards of $500,000,000 could be spent on launches alone.
Asteroids- Because they’re already *in* space, there is no need to fight earth’s gravity well.
Comets- Comets are somewhat trickier to manipulate--they’re generally fussier than asteroids due to their high volatile material content.
Moon- The moon has long been an object of Man’s envy. However, in mining the moon, one would be subject to being constrained to only the minerals that are on the Moon--there is little diversity. Also, fighting the Moon’s gravity well becomes an issue.
Asteroids are the best choice for a primary mining operation
1. Proximity-- Many come close to the Earth in predictable orbits
2. No gravity-- No gravity means no launch costs, which in turn means cheaper spacecraft
3. Diversity--Several types of asteroids exist--some metallic, some carbonaceous, some made almost entirely of ammonia
4. sheer numbers--NASA scientists think that most asteroids in the solar system are the remains of a planet never formed.
As of 1996, about 20,000 asteroids were known and tracked. 203 of them were found found to be Near-Earth Asteroids, or NEAs
According to more recent research, the number of near-earth asteroids exceeds 50,000, when asteroids 100m in diameter or larger are counted.
As you can see, there are quite a healthy number of asteroids for the taking.
This chart shows the total number of asteroids that exist, plotted against their diameters, given in kilometers. Notice the power-law nature of this chart-- there are many *many* more small asteroids than larger ones.
You might say, getting to asteroids is hard! Well, the recent NEAR-Shoemaker mission, funded by NASA, proved in 2001 that reaching asteroids is indeed possible--NEAR-Shoemaker actually “touched down” on the asteroid Eros.
The best, principal choice for an asteroid mining operation is one that comes close to earth two times in a five-year period, one that will yield both fuel and construction materials, and one that has a relatively small mass.
Type C, Apollo-class asteroids generally fulfill all of these requirements.
THis data is curtsy of the NeoDys databank. NeoDys is maintained by the University of Pisa, in Italy. Each piece of asteroid data that has been accumulated by nationally-funded and amateur astronomers has been faithfully entered into the database, which is accessible through the internet.
Although many asteroids fulfill our requirements, asteroid 1988TA does it best--it has the most optimal combination of size and orbital approaches. Finding 1988 TA was very much a chore.
Here is an orbital diagram of asteroid 1988 TA. This snapshot was taken on 13 July 2011, as the the asteroid begins to approach earth. The two dates of closest approach are given on the right. As you can see, the duration of the mining operation on 1988 TA will be approximately two years in length.
I will now hand the presentation over to my associate, Michael.
Factors considered: endurance, expense, thrust.
Nuclear Thermal are the ideal choice. Their reusability and greater thrust decreases the cost and the amount of mission time expended traveling to and from an asteroid.
The Triton rocket is a type of Nuclear thermal rocket, developed by Pratt and Whitney. It uses a fast spectrum nuclear reactor. It has the unique ability to adapt to different situations, and can be used for at least 15 missions before the propulsion system needs to be replaced.
*Note: v= {Fast spectrum alludes to higher energy neutrons (.1Mev)}
Besides it main thrust mode, which produces a large amount of thrust over a one hour time period, the Triton rocket can operate in a low power mode which generates electricity once the rocket is heading towards its destination. The Triton also can be switched to a thrust augmentation mode to increase its thrust for heavier loads.
The main propulsion system uses a CERMET fuel form, an advanced fuel based on a uranium dioxide-tungsten matrix. During operation of the TRITON engine, hydrogen is pumped through the gaps in the matrix, causing the hydrogen to become heated. The hot hydrogen gas is then ejected out of the craft producing 71,000N.
The low-power mode operates by replacing the hydrogen with a mixture of helium and xenon. This mixture is heated and is then used to simultaneously produce electricity for the ship and cool the reactor. When the reactor is being used in this fashion, it uses less then 1 percent of its maximum power, and produces anywhere from 25-50 kilowatts of electricity.
The thrust augmentation system operates by pumping liquid oxygen from an onboard tank directly into the hydrogen ejection system to allow the oxygen to interact with the extremely hot hydrogen gas. Because the oxygen hydrogen reaction is extremely exothermic the thrust increases by 200%
The TRITON rocket is only one part the Intrepid.
As the Intrepid descends to dock with the asteroid, the orbiter has been deployed, and the bow of the vessel splits apart, folding up against the sides of the craft. Once docked the mining procedure begins. The mining modual is entirely enclosed within the intrepid.
Intrepid’s mining module is equipped with a 41-blade, flat-disk mining implement, to penetrate the asteroid. Intrepid will actually be able to use the essentially nonexistent gravitational environment to its advantage: the minerals mined will be free to enter the Intrepid, due to the rotational nature of the mining saws. A conveyor system, placed along the long axis of Intrepid, is made up of multiple scoops attached to a belt, allowing it to fill a portion of the interior of the craft to contain and move the materials. These minerals are then emptied into the pressure vessel.
By mining 1988 TA one time, over 1.5 billion dollars worth of materials could be brought to earth orbit. These new resources would allow NASA to construct other Intrepid-class vessels in outer space, reducing costs dramatically. Eventually, large space stations and habitats will be constructed. Man can then begin to proliferate through the Solar system and the stars.