Mining Asteroids

Rare Platinum Nugget
U.S. Geological Survey/photo by Chip Clark, Smithsonian

If you drive a car, chances are that it uses a catalytic converter to remove toxic compounds and reduce pollution from fuel exhaust. In order to do this, the catalytic converter uses platinum or its cousin palladium, often in combination with other precious metals such as rhodium and gold.

The metals in the platinum group (platinum, palladium, rhodium, ruthenium, iridium and osmium) have important industrial, medical and scientific applications. They are expensive, however, because their supply in the earth's crust is limited.

In contrast, some asteroids, known as M-type (M for metal), contain rich quantities of platinum and other precious metals, including gold, distributed throughout.  If such asteroids could be reached, mining those asteroids could produce a valuable payload for a returning spacecraft. Before ruling this out as economically infeasible, consider this:

Our solar system contains millions of asteroids. Most of these orbit the sun in a belt between Mars and Jupiter, but there are also near-Earth asteroids (NEAs) with orbital paths either near to or crossing the orbital path of our planet. Fifty years ago, there were fewer than 70 known NEAs. As of February 1, 2014, the IAU Minor Planet Center has cataloged over 10,000 near-Earth objects that are at least 1 meter in diameter. If one or more M-type asteroids could be captured and brought into orbit around the moon, it could be reached for mining by relatively short-haul space travel.

As tantalizing as this prospect may be, asteroids contain another substance that may prove to be even more valuable than platinum or gold. That substance is water, the stuff of life comprising 50-65% of the human body. We cannot exist for long without water. This means that, to exist for long periods in space, humans must have a source of water in space.

Water - The Stuff of Life
Photo by Tim McCabe, USDA NRCS

This is why the first asteroids to be mined are most likely to be C-type (C for carbonaceous) rather than M-type. With a water content ranging up to 20% (though ~10% appears to be more common), these asteroids could provide water to support moon bases or space platforms that would make further exploration and commercial uses of space viable. In addition, volatile compounds found in such asteroids could be used to create fuel, as could hydrogen and oxygen derived from water. This, together with solar energy, could make possible the use of materials found in asteroids to build structures in places beyond our earth. Carbon and organic materials found in asteroids might even be used to grow food. Habitats in space could become nearly or completely self-sustaining.

The future is hard to predict, but baring catastrophic setbacks (perhaps of our own making), human exploration and travel beyond the moon seems inevitable. Asteroid mining may help to pave the way.

Catching Asteroids

Concept Image of Asteroid Capture

Image Credit: NASA

The goal of the NASA Asteroid Redirect Mission (ARM) is to capture a small asteroid and redirect it into an orbit around the moon, where it may become a valuable resource for scientific research, future manned space travel to Mars, and commercial asteroid mining.

The asteroid catching spacecraft to be used for this mission will be powered by advanced solar-electric propulsion, using ion thrusters designed and built at the NASA Glenn Research Center in Cleveland, Ohio.

Ion propulsion works by zapping an inert gas, such as xenon, with an electrical charge to produce fast-flowing exhaust gas.  Providing low thrust over long periods of time, ion propulsion can gradually produce a spacecraft speed of over 200,000 mhp, while using ten times less fuel than traditional rocket engines. This type of propulsion, which has already been used in smaller version by 200 or so commercial satellites since its invention at the Glenn center, makes longer space voyages more feasible.

Current plans call for the robotic capture and redirect spacecraft (which has not yet been named) to be launched in 2017. Various designs for the asteroid capture mechanism are still under consideration. One design concept calls for the use of a large inflatable bag to surround a small free-floating asteroid. Another concept envisions using robotic arms to remove a piece of a larger asteroid.

Meanwhile, work is underway to identify and characterize near-earth asteroids that might be candidates for capture. This effort also will increase our knowledge of asteroid characteristics and help to identify near-earth asteroids that may pose a collision threat, as described in Hunting Asteroids.

Hunting Asteroids

Close-up of Eros taken by NASA's Spitzer Space Telescope
Image Credit: NASA/JHUAPL

In our solar system, there many small rocky objects orbiting around the sun. When these are small, they are referred to as meteoroids; when larger than about 1 meter (3.3 yards), they are referred to as asteroids. There are millions of asteroids in our solar system, and some them -- approximately 89,000 discovered to date -- have trajectories that come near our Earth.

 In June of 2013, NASA announced a project to engage scientists and citizens in helping to "find all asteroid threats to human populations and know what to do about them" through a series of challenges, prizes, and crowd-sourcing activities. While the threat of an asteroid may be low on our list of daily worries, a direct collision is something we'd best avoid. As some may recall, in February of 2103, approximately 1500 people were injured and many thousands of buildings were damaged when a small asteroid exploded over Chelybinsk, Russia. So keeping tabs on near-Earth asteroids seems like a good idea, and one purpose of the Asteroid Grand Challenge is to find better ways of doing that.

 Offered by the NASA Tournament Lab via TopCoder, the first in the series of planned challenges, Asteroid Data Hunter, is now underway. This challenge ask participants to "develop significantly improved algorithms to identify asteroids in images captured by ground-based telescopes," specifying that the "winning solution must increase the detection sensitivity, minimize the number of false positives, ignore imperfections in the data, and run effectively on all computer systems."

Meanwhile, NASA has 50-100 volunteer amateur astronomers from around the globe helping to track and characterize asteroids.

Today at NASA's Asteroid Initiative Opportunities Forum, a group of students (shown above with their teacher) from Dillard Drive middle school described how they're participating in the International Astronomical Search Collaboration by hunting for asteroids. They are the only middle school worldwide to be participating in this activity, and today they reported on their accomplishments so far. You can learn more about this by viewing "Dillar Drive students search for asteroids" on YouTube.

As part of the Asteroid Grand Challenge, NASA is looking for ways to increase the number of amateur astronomers observing asteroids.

In addition to hunting asteroids, NASA is exploring ideas for deflecting and redirecting them. Such techniques might be exploited for research and asteroid mining, as well as for protecting our planet from damaging collisions.

Searching for Extraterrestrial Intelligence in Space and Time

Voyager 1 - Image credit: NASA/JPL-Caltech

It's estimated that there are about 30 billion trillion stars in the Universe. Recent scientific discoveries suggest that many of those stars may have planets. Indeed, current evidence suggests that there may be billions of planets similar to our Earth in their ability to support life. Is it therefore likely that we, the human inhabitants of Earth, will someday discover or make contact with extraterrestrial intelligence (ETI)? Perhaps. But in considering that question, we have to take into account the magnitude of both time and space.

Scientists currently believe the age of our Universe to be about 13.8 billions years old. Our Sun is thought to be about 5 billion years old. There's evidence that simple-celled life first appeared on earth about 3.6 billion years ago. Fossil remains suggest that homo habilis emerged about 2.5 million years ago, and homo sapiens has been around perhaps 200,000 years -- though estimates vary, as do theories about when modern human behavior emerged.

To give you an idea of how short human existence has been, if we consider the age of the Universe to be one year that began on January 1, then our sun would have appeared around August 20 and our earth around September 3.  Life in the form of simple cells would have been present near the end of September, and animals in the middle of December. Mammals would have come around December 26 and primates around December 30. The first hominids would have shown up around noon on December 31, and the first members of the genus homo would have arrived around 10:30pm. Homo sapiens would have appeared anatomically sometime sometime during the last 10 minutes of the year, begun to exhibit modern behavior perhaps in the last 2-3 minutes, and invented writing sometime during the last 15 seconds. Within this metaphorical cosmic year, the time of homo sapiens will that of one dance if we survive and thrive for another 50,000 years, and that of a thunderstorm if we last another 500,000.

Biological processes tend to be self-limiting. On earth, species have come and gone. If this is our fate and the fate of all intelligent life in the Universe, the chances of encounter depend greatly on how long it takes intelligent life to develop and how long it can survive. Let us suppose there are 100 trillion planets that will, at some point in their existence, have intelligent life capable of reaching out. If that were to happen at random for the period of one dance during my metaphorical cosmic year, we would have several hundred thousand potential partners. If the time of reaching out is more like the metaphorical thunderstorm, the number of potential partners increases to over half a billion. This may seem like good odds, but we also must take into account the vastness of space.

Consider the distance between galaxies. The Andromeda galaxy, a near neighbor of our own Milky Way, is about 163,000 light years away. If an observer within Andromeda were to have a telescope powerful enough to see the surface of the earth in detail, looking today they would be seeing the earth as it was ~163,000 years ago. Thus, they might see hominids (including Neanderthals) making tools of bone and stone, living in shelters, wearing clothing and controlling fire. That observer might conclude that there was intelligent life on earth, and might also decide to attempt communication in hope that by the time the signal arrived, the intended recipients would have the technology to detect it. In 163,000 years or so from today, that signal would arrive.

Given the time-distance involved, unless we learn how to communicate faster than the speed of light, it seems unlikely that we'll be exchanging signals any time soon with intelligent life outside our own galaxy. However, within our own Milky Way, which spans at least 100,000 light years in its longest direction, the Kepler space telescope has found over 1700 planets that are within 3,000 light years from earth. That's just since 2009, and our ability to find planets has recently gotten better. We now have reason to believe that there are many planets out there orbiting stars whose distance in light years is comparable to the 5,000 or so years since the earliest known evidence of writing.

Now, as a hypothetical exercise, let's suppose that the ~600 million stars within that distance have an average of one planet each that's in the habitable zone, and that complex life develops on 10% of those. If intelligent life is but a dance occurring randomly within the cosmic year, we would have 100 or so potential partners. If it's a thunderstorm, that number expands to over 3,000. If, on the other hand, it takes about the same amount of time for intelligent life to emerge on each planet, our chances of detecting it would be much greater. In addition, there's the chance of finding evidence of an intelligent civilization that once was and is no more.

Even so, what these back-of-the-envelope calculations suggest to me is that the search for ETI is an act of optimism, grounded in the hope that intelligence confers the ability to plant a continuing harvest for posterity rather depleting the soil or sowing the seeds of its own destruction.

A Small Neighborhood in Fornax

My last post was about an image I created using FITS data I got from SkyView. Here's an image from NASA showing a larger view of the same region in space. This is a small area in the celestial sphere, spanning only one minute of arc. It's located in the constellation Fornax, which occupies an area of 398 square degrees. The name Fornax comes from the French astronomer Nicolas Louis de Lacaille, who first formed this constellation and called it Fornax Chimiae ("chemical furnace").

The constellation Fornax can be seen from the southern sky, but the stars and galaxies shown in the image above cannot be seen with the naked eye. They are in what's known as a "dark field," a region where there is not much background radiation. By surveying such regions with the Hubble Space Telescope, astronomers are able to detect and study faint galaxies in the early universe to learn more about how galaxies evolve.

FITS Liberator Image from 03h32m29.3s, -27d44m10.0s (J2000)

This is an image I created today using the FITS Liberator with data obtained from SkyView. What you're seeing is an area of deep space that was surveyed by the Hubble Space Telescope Advanced Camera for Surveys (HST ACS). I got the FITS data by giving SkyView the coordinates 03h32m29.3s, -27d44m10.0s (J2000 co-ordinate system) and specifying regions .02 degrees in size.

To get a color image, I downloaded three sets of FITS data, each covering the same area of space, but with different filters for wavelength. Using the FITS Liberator, I converted each data set into a TIFF image. I then loaded the TIFF images in to Adobe Photoshop to make a stack of three layers and gave a different color (i.e. red, green, blue) to each layer. After making some curves adjustments, I got the image you see above.

Making this image involved a series of subjective judgements, first in managing the dynamic ranges of images with the FITS Liberator, and then in tweaking curves in Photoshop. So the image you see should be considered an artistic rendering of astronomical data rather than a "snapshot" of outer space. I did, however, try to keep the colors basically "natural" by assigning blue to the shortest frequency filter, red to the highest frequency, and green to the one in the middle.

When looking at my image, you may be wondering if there's a way to describe the part of space it shows other than by the coordinates I've provided. I was wondering that too, at first!  I've never taken a class in astronomy, and I understand less than half of what I read on the subject. However, I'm fascinated by astrophotography. So my approach to learning about astronomy has been to find interesting images and then try to understand what they show. If you're an astronomy buff, you may know what my image shows. Otherwise, you're going to have to wait for me to post more information.

Orion Nebula

Photo Credit:  Jim de Lillo and the ESA/ESO/NASA FITS Liberator

Jim de Lillo created this stunning image of the Orion Nebula from three 120-second exposures he took using the Lightbucks Remote Telescope Network LB-0004 in Pingelly, Australia.

The Pink Planet

Artist's conception of GJ 504b
Image Credit: NASA's Goddard Space Flight Center/S. Wiessinger

Planets are hard to "see" because they orbit around stars that are much bigger and brighter. For this reason, most of the planets we know of outside our own solar system have been detected and studied using measurements and mathematics.

In recent years, though, it's become increasingly possible to detect certain kinds of planets from the direct observations of scientific telescopes, which can use filters to capture infrared radiation and turn it into visible images.

The planet GJ 504b, dubbed the "pink planet" was recently imaged in this way using infrared observations from the Subaru Telescope on Mauna Kea in Hawaii. Most of the planets observed so far by direct imaging have been large and relatively far away from the sun they orbit. The pink planet fits that description, but it currently holds the record for being the least massive planet observed in this way. Even so, it's a large planet like Jupiter.  It's that similarity to Jupiter together with its distance from its sun that makes GJ 504b interesting to astronomers.

If planets like Jupiter form within the gas disc of a young star, as many astronomers have believed, then you'd expect to find such planets no farther away from their sun that the planet Neptune is from our sun -- a distance of 30 AU (astronomical units). Contrary to this prediction, GJ 504b is estimated to be 43.5 AU from its sun. That's difficult to explain with any of the current theories about how planets are formed.

What's easier to explain is why GJ 504b is pink. It's part of a relatively new solar system that was formed only ~160 million years ago, making it 30 times younger than our earth, so the planet is still cooling down. It's lost some of its heat, making it cooler than other planets that have been directly imaged, but it's still hot enough to have a magenta glow.

The Blue Planet

Artist's conception of HD 189733b.
Image Credit: NASA, ESA, M. Kornmesser

If you are in a good stargazing location near the 40th parallel north on a summer night, you may be able to see a faint constellation known as Vulpecula located within the triangle formed by the stars Deneb, Vega and Altair. If you have a telescope or a good set of binoculars, you might be able to see a binary star system that astronomers refer to as HD 189733.

One of the stars in this binary system, which is a mere 63 light-years or so from earth, has a planet designated as HD 189733b. This planet, which was discovered in 2005, is a gas giant that orbits close to it's sun. Planets of this type are sometimes called "hot Jupiters," and HD 189733b has been an object of study because it's the closest planet of this type that we know.

According to NASA & ESA, the sun-facing side of this planet is a furnace, with surface temperatures reaching nearly 2000°F and glass "rain" blowing sideways in up to 4,500-mph winds. It seems unlikely that life could exist under these conditions, yet this planet has provided information that's relevant to the question of whether life may exist on outside our solar system. HD 189733b was the first exoplanet on which water was detected (see NASA JLP article "Steaming Hot Planet" for details), and water is deemed essential for the survival of lifeforms as we know them. In addition to having significant amounts of water vapor, the atmosphere of HD 189733b has been found to contain oxygen, carbon dioxide and the organic compound methane (see NASA/ESA article "Hubble finds carbon dioxide on an extrasolar planet" . If these substances are common on planets outside our solar system, we may someday find them on planets similar to our earth in size and distance from their sun.

HD 189733b has recently been in the news because of it's color. What's special about the color of this planet is that we now know it. Planets are difficult to "see" in the usual sense, so scientists discovered the color in this case from careful measurements and logical inference. If you're interested in knowing more about how this was done, you can read the details in the new release "Hubble spots azure blue planet."

Astrophotography with FITS Liberator

Modern astronomical telescopes save their raw data in a format known as FITS (Flexible Image Transport System). The colorful images we see from space are created by transforming FITS imaging data into a standard graphical format, such as TIFF, to create a set of files that can be imported into an image editing application such as Photoshop or GIMP. If you know how to use image editing software, you can create your own "pretty pictures" of astronomical subjects by obtaining FITS files (available from a number of sources) and using the FITS Liberator to transform them into TIFF images.

FITS Liberator, developed by ESA/ESO/NASA, was originally a plug-in for Adobe Photoshop.  With the release of version 3, the open-source FITS Liberator has become a stand-alone application, with versions available for both Windows and Mac OS X.

Using FITS data I obtained from NASA's virtual observatory, SkyView, I created the above image of M51, also known as the Whirlpool Galaxy.  There are no doubt better images of M51 around, but this one is uniquely mine. Creating it was a fun learning experience.

You can learn more about FITS data and how to obtain it from The FITS Support Office
at NASA/GSFC and from Image Processing Resources for Astronomy Teaching by by the Astronomy Education Committee of the American Association of Physics Teachers.

Stellar Spire in the Eagle Nebula

Photo Credit: NASA, ESA, and The
Hubble Heritage Team (STScI/AURA)

I enjoy viewing astrophotography.  Images from space have a special beauty, and I find that contemplating the scope of the cosmos helps to put my own small problems in perspective.

The image I'm posting today shows a spire or pillar in the Eagle Nebula, located in the Sagittarius Arm of the Milky Way galaxy.  I enjoy the NASA news release accompanying this image as much as the image itself:

"Appearing like a winged fairy-tale creature poised on a pedestal, this object is actually a billowing tower of cold gas and dust rising from a stellar nursery called the Eagle Nebula. The soaring tower is 9.5 light-years or about 57 trillion miles high, about twice the distance from our Sun to the next nearest star.

Stars in the Eagle Nebula are born in clouds of cold hydrogen gas that reside in chaotic neighborhoods, where energy from young stars sculpts fantasy-like landscapes in the gas. The tower may be a giant incubator for those newborn stars. A torrent of ultraviolet light from a band of massive, hot, young stars [off the top of the image] is eroding the pillar.

The starlight also is responsible for illuminating the tower's rough surface. Ghostly streamers of gas can be seen boiling off this surface, creating the haze around the structure and highlighting its three-dimensional shape. The column is silhouetted against the background glow of more distant gas.

The edge of the dark hydrogen cloud at the top of the tower is resisting erosion, in a manner similar to that of brush among a field of prairie grass that is being swept up by fire. The fire quickly burns the grass but slows down when it encounters the dense brush. In this celestial case, thick clouds of hydrogen gas and dust have survived longer than their surroundings in the face of a blast of ultraviolet light from the hot, young stars.

Inside the gaseous tower, stars may be forming. Some of those stars may have been created by dense gas collapsing under gravity. Other stars may be forming due to pressure from gas that has been heated by the neighboring hot stars.

The first wave of stars may have started forming before the massive star cluster began venting its scorching light. The star birth may have begun when denser regions of cold gas within the tower started collapsing under their own weight to make stars.

The bumps and fingers of material in the center of the tower are examples of these stellar birthing areas. These regions may look small but they are roughly the size of our solar system. The fledgling stars continued to grow as they fed off the surrounding gas cloud. They abruptly stopped growing when light from the star cluster uncovered their gaseous cradles, separating them from their gas supply.

Ironically, the young cluster's intense starlight may be inducing star formation in some regions of the tower. Examples can be seen in the large, glowing clumps and finger-shaped protrusions at the top of the structure. The stars may be heating the gas at the top of the tower and creating a shock front, as seen by the bright rim of material tracing the edge of the nebula at top, left. As the heated gas expands, it acts like a battering ram, pushing against the darker cold gas. The intense pressure compresses the gas, making it easier for stars to form. This scenario may continue as the shock front moves slowly down the tower.

The dominant colors in the image were produced by gas energized by the star cluster's powerful ultraviolet light. The blue color at the top is from glowing oxygen. The red color in the lower region is from glowing hydrogen. The Eagle Nebula image was taken in November 2004 with the Advanced Camera for Surveys aboard NASA's Hubble Space Telescope."

Jupiter Portrait from NASA

NASA provides wonderful images.  This is a true color portrait of Jupiter, composed from images taken by the Cassini spacecraft on December 29, 2000, during its closest approach to the planet.

According to the NASA website:  "Everything visible on the planet is a cloud. The parallel reddish-brown and white bands, the white ovals, and the large Great Red Spot persist over many years despite the intense turbulence visible in the atmosphere. The most energetic features are the small, bright clouds to the left of the Great Red Spot and in similar locations in the northern half of the planet. These clouds grow and disappear over a few days and generate lightning. Streaks form as clouds are sheared apart by Jupiter's intense jet streams that run parallel to the colored bands. The prominent dark band in the northern half of the planet is the location of Jupiter's fastest jet stream, with eastward winds of 480 kilometers (300 miles) per hour."  "Unlike Earth, where only water condenses to form clouds, Jupiter's clouds are made of ammonia, hydrogen sulfide, and water."

You can see a scalable version of this Jupiter Portrait on the NASA Images website, where you will find many other extraordinary photographs and visualizations.  For more information on the Cassini mission and its images, visit JPL's Cassini pages and the Cassini Imaging website.


Image Credit:  NASA/JPL/Space Science Institute