Asteroid Mining: Gold Rush in Space?
AbstractYou've heard of gold mining and coal mining, but think outside the box...or the planet...what about asteroid mining? Scientists, engineers, and business people believe asteroid mining is feasible, and they are in the beginning stages of long-term plans to mine asteroids for valuable resources during space missions. You don't want to miss out on all the fun; in this science project, you will come up with your own scientific plan for an asteroid mining company. We will help get you started by introducing you to a huge database that NASA uses to keep track of asteroids. This database will help you identify potential target asteroids for your mining company so your company can strike it rich.
Ben Finio, Ph.D., Science Buddies
Use a NASA asteroid database to identify asteroids that may be feasible destinations for early asteroid mining missions.
Have you ever seen a movie or played a video game where spaceships fly daringly through asteroid fields, and even land on asteroids? Those space adventures are far from just science fiction! The unmanned Japanese spacecraft Hayabusa actually landed on an asteroid and returned a sample to Earth! Now, there is even a startup company called Planetary Resources, formed with the goal of commercially mining asteroids for resources and raw materials in space (see the Bibliography to learn more). But, if asteroids are just chunks of rock floating in space—either left over from the formation of our solar system, or created when two larger objects (like planets, moons or even bigger asteroids) collided and smaller chunks broke off—why would anyone want to mine them? Asteroids actually contain many potentially useful materials; metals like iron can be used for construction, some rare metals like platinum are very valuable, and water could provide a potential source of drinking water for astronauts, or be converted into rocket fuel (by first breaking it down into hydrogen and oxygen).
Asteroids can range in size from just a few meters (m) across to 1,000 kilometers (km) across, and many of them have irregular shapes (see Figure 1). They are also distributed all throughout our solar system—mostly in the asteroid belt between the orbits of Mars and Jupiter—although there are many other smaller groups of asteroids (shown in Figure 2).
The largest asteroid 4 Vesta, has an average diameter of 525km. The smallest 25143 Itokawa has a length of 630 m and a width of 250 m.
Figure 1. A scale image of several different asteroids. The largest, 4 Vesta, has an average diameter of 525 km. The smallest, 25143 Itokawa (barely visible in this image), is an ellipsoid with a length of 630 m and a width of 250 m.
The blue lines represents the planet orbits around the sun while the asteroids are represented by white dots
Figure 2. This image shows the distribution of asteroids within our solar system. The planets' orbits around the Sun are represented by elliptical blue lines, and asteroids are represented by dots. Most of the asteroids are clustered in the "main belt" (white dots), but there are other smaller groups of asteroids (not all of them are labeled in this image). There are also more asteroids in the "outer" solar system (e.g. by Neptune), which are not shown in this image.
In this astronomy science project, you will develop a rough scientific business plan for your very own asteroid mining company. However, mining asteroids is a dangerous and expensive venture, and it can take years for a spacecraft to reach an asteroid (the Hayabusa craft left Earth in September 2003, landed on an asteroid in November 2005, and did not return to Earth until June 2010!). This means that simple pictures of asteroids (like Figure 1) and a rough map of the solar system (Figure 2) won't be sufficient. To ensure the voyage is worthwhile, you need to do research and data analysis to determine which asteroids your company will attempt to mine, based on your scientific plan. Luckily, the National Aeronautics and Space Administration (NASA) and the Jet Propulsion Laboratory (JPL) have an enormous computerized database that contains information about hundreds of thousands of asteroids. In order to decide which asteroids you want to mine, you will need to learn more about the information in this database.
So, what data does NASA actually track about asteroids? The JPL database contains information about their orbits, or trajectories through space as they rotate around the Sun. Asteroids' orbits are elliptical, as shown in Figure 3. Several different parameters define an asteroid's elliptical orbit. The basic parameters you need to know for this science project are:
- Semi-major axis is a distance equal to one-half of the major axis of an ellipse. The major axis passes through the center of the ellipse and ends at its widest points (see Figure 3). Semi-major axis is measured in astronomical units (AU). One AU is equal to Earth's average distance from the Sun.
- Perihelion is the object's closest distance to the Sun (see Figure 3). Perihelion is also measured in astronomical units.
- Aphelion is the object's farthest distance from the Sun (see Figure 3). Aphelion is also measured in astronomical units.
- Eccentricity measures how "circular" an orbit is. A perfect circle has an eccentricity of 0. As an ellipse becomes longer and skinnier, its eccentricity approaches (but never reaches) 1. Eccentricity does not have units.
- Inclination measures the angle between the plane of an asteroid's orbit and the plane of Earth's orbit around the Sun. Inclination is measured in degrees (deg).
- Orbital period is how long it takes the asteroid to orbit the Sun once. Orbital period is measured in years (y).
Semi-major axis is the distance equal to one-half of the major axis of an ellipse. Semi-major axis is measured in astronomical unites. One astronomical unit is equal to Earth's average distance from the Sun. Perihelion is the object closest to the Sun. Aphelion is the object that’s farthest from the Sun.
Figure 3. Some of the parameters defining an elliptical orbit.
The database also includes physical information about each asteroid. Some of the physical information includes:
- Diameter, the asteroid's approximate diameter (note that many asteroids are not perfectly spherical, so this is an average diameter). Diameter is measured in kilometers.
- Extent measures the dimensions (length, width, and height) of a "box" that would fit around the asteroid. For a perfectly spherical object, all three numbers would be the same. Extent is measured in kilometers.
- Albedo is a measurement of how much light the surface of the asteroid reflects. Albedo does not have units. A value of 0 means that no light is reflected, and a value of 1 is the amount of light that would be reflected off of a perfectly flat, white, diffusing surface (meaning light is scattered in all directions). Most asteroids have an albedo ranging from 0.01 (very dark) to 0.7 (very bright).
- Rotation period is how long it takes the asteroid to spin about its own axis. Be careful not to get this mixed up with orbital period. Rotation period is measured in hours (h).
- GM is an expression of the asteroid's mass, M, multiplied by the universal gravitational constant, G (see the Technical Note about converting this number to mass in kilograms). GM is measured in kilometers cubed per seconds squared (km3/s2).
- Spectral type is an asteroid's classification according to information about how it reflects electromagnetic radiation (like radio waves, visible light, microwaves, and X rays), which gives scientists an idea of what materials the asteroid is made of. There are two primary classification systems:
the Tholen system and the SMASS system. While there are some differences between the two systems, in general, asteroids can be grouped into three main categories (there are additional smaller groups and sub-groups not listed here):
- C-type or "carbonaceous" asteroids, which contain carbon compounds. This is the most common type of asteroid, making up about 75% of known asteroids. They consist primarily of clay and rocks, but can also contain large amounts of water.
- S-type ("silacaceous" or "stony") asteroids. These are the second most common type, about 17% of known asteroids. They consist mostly of stony materials (silicates), and nickel-iron, but can also contain valuable metals like platinum.
- M-type (also called X-type depending on the classification system) or "metallic" asteroids. These asteroids consist mostly of nickel-iron and other metals.
Note: Hover over the formulas in this section with your cursor to enlarge them.
GM is an expression of an asteroid's mass in units of the mass, M, times the gravitational constant, G, which is defined as
or (converting the distance units to kilometers instead of meters)
So, in order to calculate the mass, M, of an asteroid in kilograms, you have to divide the product, GM, by the gravitational constant, G:
Be careful to keep track of units. The physical parameter table (you will see this in the procedure) gives GM in km3/s2, so you should use the second value for G when calculating mass.
For example, GM for the asteroid 25143 Itokawa (which was landed on by the Hayabusa spacecraft) is
Dividing this by G gives the asteroid's mass, M:
That's over 30 billion kg (1 billion is 109)!
How exactly will all of this information be useful in determining which asteroids to mine? Before moving on to the Procedure section, check out some of the references in the Bibliography to help you get some ideas.
Terms and Concepts
The following terms were defined in the Introduction:
- Asteroid belt
- Asteroid orbit parameters:
- Semi-major axis
- Astronomical units (AU)
- Orbital period
- Asteroid physical parameters:
- Rotation period
- Spectral type:
- M-type or X-type
- What are the main types of asteroids? What materials are they made of?
- How could these materials be useful, either in space or on Earth?
- How are asteroids distributed throughout the solar system? Which asteroids would be easiest to reach from Earth?
- How do scientists on Earth gather information about asteroids?
- How much does it cost to launch 1 kg of cargo into space from Earth's surface? How much money could be saved if you could mine those materials in space instead? You do not need exact answers now, but this type of question might help you formulate your business idea.
These resources will be useful for learning more about asteroids, including the different types of asteroids, their locations in the solar system, and how we might go about mining them. You will need to do a lot of background research for this science project in order to form a good plan for an asteroid mining company.
- NASA. (n.d.). Near Earth Object Program - Introduction & Overview. Retrieved July 15, 2013.
- Wikipedia contributors. (2013, February 25). Asteroid Spectral Types. Retrieved July 15, 2013.
- Amos, J. (2010, June 14). Hayabusa asteroid-sample capsule recovered in Outback. Retrieved July 13, 2013.
- Planetary Resources. (n.d.). Asteroid Overview. Retrieved July 13, 2013.
- NASA Solar System Exploration. (n.d.). Asteroids - Overview. Retrieved July 13, 2013.
- Clavi, W. and Harrington, J.D. (2013, July 25). NASA's WISE Finds Mysterious Centaurs May Be Comets. Retrieved August 9, 2013.
- Jet Propulsion Laboratory. (n.d.). JPL Small-Body Database Search Engine. Retrieved August 20, 2013.
- Jet Propulsion Laboratory. (n.d.). JPL Small-Body Database Browser. Retrieved August 20, 2013.
Materials and Equipment
- Computer with internet access
Developing a Plan
In this science project, you will create a scientific business plan for your future asteroid mining company and make a list of asteroids of interest to your company.
- Develop a preliminary concept or business idea for an asteroid mining company. We will provide some ideas to get you started, but feel free to be creative and come up with your own ideas!
- Your company could mine asteroids that are near Earth for precious metals like platinum, and bring the metals back to sell on Earth.
- Your company could target iron-rich asteroids in the inner solar system in order to mine raw materials for building a space station or a colony on Mars.
- Your company could mine asteroids toward the outer edge of the asteroid belt for materials that can be turned into rocket fuel, to make a "refueling station" for spacecraft that are traveling toward the outer solar system.
- Your company could mine water from asteroids to provide drinking water for astronauts who are on long space missions.
- Based on your background research, identify types and locations of asteroids that make the most sense to mine based on your business idea.
- For example, if you need to mine water, then you probably want to target C-type asteroids, not S-type or M-type.
- If you want to mine a specific type of rock, metal, or mineral, then you will need to do more background research on the specific compositions of the different asteroid spectral types.
- If you want to bring materials back to sell on Earth, you probably want to target asteroids near Earth. However, this might not be the case if you want to build a space station near Mars or a refueling station near Jupiter.
- Now that you have a business idea and a preliminary idea of what types of asteroids you want to mine, you need to start identifying some asteroids. There are two very useful tools that will help you do this (we will walk you through examples).
- The JPL Small-Body Database Search Engine allows you to search for asteroids based on specific criteria. For example, you could use it to find all of the Jupiter Trojans, all C-type asteroids, or all asteroids with a diameter greater than 1 km (or any combination of these criteria).
- The JPL Small-Body Database Browser provides data about all known asteroids. You can search for an individual asteroid using its name or identification number, and the results will bring up all the known information about that asteroid.
Using the Small-Body Database Search Engine
The JPL Small-Body Database Search Engine allows you to do a detailed search to narrow down a list of potential asteroids, once you have identified criteria.
- The search engine has several different sections. We will explain them one at a time. The first is the "Search Constraints" box, shown in Figure 4.
- The Search Constraints box lets you narrow down your search using radio buttons (buttons representing one of a set of options, only one of which can be selected at any time) to select object groups (all objects, near Earth objects [NEOs], or potentially hazardous asteroids [PHAs]), object kinds (all objects, asteroids, or comets), and numbered state (all objects, numbered, or unnumbered; not all asteroids have been assigned a number, but this will not really impact the results for your science project, so you can just select "All objects").
- You can also narrow down your search using checkboxes to select orbit classes. You may need to do background research to learn more about the different types of orbit classes.
- The "Limit by object characteristics" section lets you select ranges for physical parameters in the results of your search. For example, Figure 5 shows a search setting to include all asteroids with diameters greater than or equal to 1 km and all asteroids with a semi-major axis of less than or equal to 3 AU. You can read the Small-Body Database Search Engine tutorial to learn more about how to use this feature.
Small-body search constraints window. A user can search by object type/group, selected orbit class, and limit by object characteristics to obtain specific results. A user can choose object group, object kind, numbered state in the top portion. In the middle section, a user can choose if they want their results from the asteroid orbit class or comet orbit class. In the last section, a user can determine physical parameters and orbital parameters.
Figure 4. The "Search Constraints" section of the JPL Small-Body Database Search Engine.
The top image sets the physical parameter to 1, however results won't show until the "Add =>" is pressed. The bottom image shows results, in this case it has been set to find all asteroids with diameteres greater than or equal to 1 km and with semi-major axes less than or equal to 3 AU.
Figure 5. The top image shows that to add a physical parameter to your search criteria, use the drop-down menus on the left and then click the "Add =>" button. The bottom image in this figure shows a search that has been set to find all asteroids with diameters greater than or equal to 1 km and with semi-major axes less than or equal to 3 AU.
- The "Output Fields" section determines what values will be included in the output of your search. You can use this to make sure your search only outputs information that you will find useful, instead of lots of extraneous information.
- Figure 6 shows a screenshot of the Output Fields section.
- You can add individual parameters to the output of your search by selecting them from the "Object Fields" and "Orbital and Model Parameter Fields" lists, then by clicking "Append Selected" (adds them to the end of your output) or "Prepend Selected" (adds them to the beginning of your output).
- Instead of adding individual parameters, you can also add pre-defined lists from the "Pre-defined field sets" area. The information you need in this science project is contained in the "asteroid — basic" and "asteroid — physical" sets.
- Once you have added parameters, you can rearrange and remove them using the "Move Up", "Move Down," and "Remove" buttons (Figure 7).
A user can choose filters from Object Fields and Pre-defined fields to have specific search results. By clicking the Append Selected or the Prepend Selected, it will add it to your output.
Figure 6. The "Output Fields" section of the Small-Body Database Search Engine is used to determine what parameters will be included in your search output. Select a parameter then click "Append Selected" or "Prepend Selected" to add it to your output.
Field sort options screen including options to move up, move down and remove fields.
Figure 7. Use the "Move Up", "Move Down", and "Remove" buttons to rearrange parameters that you have added to your output list.
- The "Format Options" section lets you determine whether you want to view your results in your internet browser, or download them as a comma-separated variable (CSV) file.
- Figure 8 shows a screenshot of the "Format Options" section. Select "HTML" to generate a table of results in your internet browser.
- Clicking on "Generate Table" will create a table of your search results, like the one in Figure 9.
- Within your table, you can click on the name of a column header (object fullname, a, period, etc.) to sort the table by that column. You can also click on the name of the asteroid in the left column to bring up its info page in the Small-Body Database Browser, described in the next section.
Small-body database search window showing table format (HTML or CSV formats) and precision options (reduced precision and full-precision).
Figure 8. The "Format Options" section of the Small-Body database search. Click "Generate Table" to create a table of your search results.
JPL Small-Body database search engine showing asteroids with a diameter greater than or equal to 1 km and a semi-major axis less than or equal to 3 AU. Clicking on the asteroid's name in the left column will bring up the asteroid's information page. Clicking on the name of a column on top of the table will sort the table.
Figure 9. The first page of search results for all asteroids with diameters greater than or equal to 1 km and semi-major axes less than or equal to 3 AU. Clicking on an asteroid's name in the left column will bring up that asteroid's information page in the Small-Body Database Browser. Clicking on the name of a column at the top of the table (for example "period" or "diameter") will sort the table by that column.
Using the Small Body Database Browser
This section will give you an overview of how to use the JPL Small-Body Database Browser. It will be useful for looking up detailed information about individual asteroids once you have identified prospects using the search function.
- As an example, let us use the Small-Body Database Browser to look up 25143 Itokawa, the asteroid that the Japanese spacecraft Hayabusa landed on.
- You can find 25143 Itokawa by typing "25143", "Itokawa", or "25143 Itokawa" (not case-sensitive) in the search box and then pressing enter, as shown in Figure 10:
Introduction/overview of the JPL Small-Body Database Browser. Enter the IAU number, name, or an object in the search box in the upper right hand corner. The database has data including orbital elements, orbit diagrams, physical parameters, and discovery circumstances. Discovery circumstances are updated on a monthly basis. Physical parameters, other than magnitude parameteres, are updated less frequently.
Figure 10. A screenshot of the JPL Small-Body Database Browser. Use the search bar in the upper right to search for individual asteroids.
- This brings up a screen with a lot of information about the asteroid, which may seem overwhelming at first, but do not worry! We will walk you through each part of the screen.
- The first table shows the orbital elements (Figure 11).
- These are the variables that describe the asteroid's orbit (you learned about some of them in the Introduction), and may be useful in determining if an asteroid is in a location that your business wants to target.
- Most of the orbital elements in the table use abbreviations. Click on the abbreviation to see the full name. For example, if you click on the lowercase "q", a pop-up window tells you that this is the perihelion distance, measured in AU.
By using the JPL Small-Body Database Browser, we can see the element, value, uncertainity, units, and orbit determination parameters for the asteroid.
Figure 11. The orbital elements for the asteroid 25143 Itokawa from the JPL Small-Body Database Browser.
- Next is a table of physical parameters (as shown in Figure 12). This table contains physical information about the asteroid, and may be useful in determining whether it is the type of asteroid you want to target.
This table shows the parameter, symbol, value, units, sigma, and reference of the asteroid. The parameter has information about absolute magnitude, diameter, extent, GM, bulk density, rotation period, and SMASSII spectral type.
Figure 12. The physical parameter table for the asteroid 25143 Itokawa from the JPL Small-Body Database Browser.
- Finally, you can view a table of close-approach data. You can open this table by clicking "[show close-approach data]" in the bottom left corner of the window, as shown in Figure 13. This table contains information about when the asteroid will pass close to Earth, including the date and time of the approach, the distance to Earth (the column titled Nominal Distance (AU)), and other information.
Hideo Itokawa was known as the Father of Japanese Rocketry. He made rockets and put Japan's first satellite into orbit. Click the "Close-Appproach Data" in the bottom right to view a table of the close--approach data.
Figure 13. Click "[show close-approach data]" in the bottom left corner of the Small-Body Database Browser to open the table of close-approach data.
- Calculating the trajectory a spacecraft must take to leave Earth and intercept an asteroid is very complicated, and you will not be expected to do that for this science project. However, you may be able to make some rough estimates by looking up information on other spacecraft. For example, the Hayabusa probe took 2 years and 4 months to reach Itokawa after leaving Earth. Can you look up information about other spacecraft (for example, the Mars Rovers or the Voyager probes) to determine roughly how long it takes to reach different locations in the solar system?
Bringing it All Together
Now you know a lot of background information about asteroids, including what they are made out of and where they are in the solar system. You know how to use helpful online tools that allow you to look up detailed information about asteroids, and you should have a rough business idea for an asteroid mining company. So, now it is time to use all of this information to identify the best asteroids for your company to explore.
- Using criteria you have identified for your asteroid mining company, use the JPL Small-Body Database Search Engine to find a list of asteroids that meet your criteria.
- View data about individual asteroids in the JPL Small-Body Database Browser.
- Try to identify a reasonably sized list of potential asteroids, like a "Top Ten" list. If you do not use enough search criteria, your search may return hundreds or even thousands of results, and that much information will not be easy to use.
- If you are having trouble narrowing down your list, try to come up with additional criteria. Here are a few more examples; remember that these are just suggestions, and you can come up with your own ideas based on your goal for your asteroid mining company.
- Some asteroids are very small (only a few meters across) and some are very large (several hundred kilometers across). Do you want to try to "capture" very small asteroids and bring them back to Earth? Or do you want to land on large asteroids and mine from their surfaces? What about something in between?
- How often do the asteroids pass close to Earth? How soon will their next close approach be? Will you be able to reach some asteroids sooner than others? What about a long-term business plan; for example, if you want to reach one asteroid every 5 years for the next 50 years?
- What do you think would determine how difficult it is to land on an asteroid? For example, some asteroids have very irregular shapes (you may need to find a picture of the asteroid to tell how it is shaped), and some spin very rapidly. Would that make it harder to land on the surface and mine?
- How much material do you think a spacecraft could bring back from an asteroid in one trip? For large asteroids, would you have to plan multiple trips back and forth to the same asteroid?
Ask an Expert
- There are even more objects in the outer solar system; for example the "Trans Neptunian" asteroids, and objects in the Kuiper Belt. Develop a deep-space mining plan for objects in the outer solar system. Are the compositions of objects in the outer solar system different from those in the inner solar system?
- What happens if you include comets in your search, instead of just asteroids? Do background research to learn the differences between comets and asteroids. Does it make more sense to mine one than the other?
- Make some very rough estimates for the financial aspect of your asteroid mining company. For example, consider these questions:
- How much does it currently cost to launch 1 kg of material into space from Earth's surface?
- How much money does it cost to launch satellites, probes, and other spacecraft to different locations in the solar system (for example, the Hayabusa probe, which made a round trip to an asteroid)?
- How much money could be saved by mining 1 kg of water (or another material) in space instead of launching it from Earth? How many kilograms of water would you need to mine to make up for the cost of launching a spacecraft to an asteroid?
- How much would raw materials from asteroids be worth if you could sell them on Earth?
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