Visiting an asteroid

December 17, 2010
A photo of the magnesium-silicate bearing asteroid Steins, as taken by the Rosetta spacecraft as it passed through the asteroid belt en route to a comet. Credit: Rosetta and ESA

Asteroids (or comets) whose orbits bring them close to the earth's orbit are called Near Earth Objects (NEOs). Some asteroids are old, dating from the origins of the solar system about four and one-half billion years ago, and expected to be rich in primitive materials. They are of great interest to scientists studying the young solar system. Other NEOs, although not as rich in primitive materials, are thought to contain minerals of potential economic value. NASA has been thinking about sending a manned mission to an NEO for research, and has been motivated as well by a national interest in their possible commercial value.

Picking an NEO for a potential landing site involves at least two basic considerations. The first is knowing whether the asteroid's composition is primitive, or otherwise. This can be determined by measuring the surface character via the sunlight reflected from the surface (primitive materials usually appear dark), and/or by that can ascertain the minerals more reliably.

The second consideration involves picking an NEO whose orbit allows it to be reached by a with relative ease and energy efficiency, since some NEOs, even though passing closer to earth, are harder to reach.

CfA astronomers Joe Hora, Giovanni Fazio, Howard Smith, and Tim Spahr, together with a team of colleagues, have been using the infrared camera on the and ground-based telescopes to determine the size and composition of 700 NEOs, more than ten times the number now so characterized. In a series of three new papers the team describes their thermal model and its successes in describing NEOs (the smallest one they have measured to date is only 84 +-14 meters in diameter); they model one NEO in detail, and characterize sixty-five other NEOs that are suitable for a manned mission because they are relatively easy to reach.

Seven of sixty-five appear to be very dark, and are probably primitive asteroids; the others have a range of compositions including silicate-rich minerals containing iron and magnesium. The new research extends our understanding of the nature of NEOs. Although planning for a to an asteroid is still in the early stages, the research also will help decision-makers choose a suitable destination.

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5 / 5 (2) Dec 17, 2010
No, no no! Spend a smaller amount of money on robotic missions to NEOs and a larger potion on robotic missions to the moon. The moon has been bombarded by NEOs for billions of years. If there are resources of value on NEOs, there will the same on the moon. When this is proven, as are copious amounts of water, spend more money on manned lunar bases to establish mining and manufacturing facilities and as staging areas for further, PERMANENT, human expansion into space.
2.7 / 5 (3) Dec 17, 2010
When is someone going to start a "Probe" company!? Start cranking out robotic probes for various applications vis a vis Star Trek.

Class I probes -- cheap, ion propulsion, basic sensors for NEO cataloging and roaming the asteroid belt.
Class II probes -- larger instrument suite, nuclear/VASIMR engines
Class III probes -- stationary landers
Class IV -- mobile landers

Seems like we spend far too much money creating one-off probes for single use. Seems like a network of like-designed probes constantly being seeded throughout the solar system would be cost effective and more scientifically beneficial.
4.3 / 5 (3) Dec 17, 2010
Seems like we spend far too much money creating one-off probes for single use

Think about it in terms of writing a computer program.

The state of the art of hardware changes over time. Needs change over time. The best thing you can make today is obsolete in a few years.

It takes many years to build and launch a robotic probe. While some parts can be copied and pasted from previous work, you would not want to spend the money it takes break earth orbit and launch an obsolete piece of equipment. You also would not want to use some kind of generic design that really doesn't meet any of your needs 100% just so that you could save a few bucks on probe design. When we start going back to the moon in earnest, it could be with copy-cat robots like the twin mars rovers, but that's a special case.

the risk is that you make 10 (or 2) identical robots, then find out that they are all flawed when you launch them.
4 / 5 (1) Dec 18, 2010
The only reason for maintaining a heavy lift capability right now is to get a space elevator for the earth started. It is a bit frustrating that today we have the technology to build space elevators for the moon and Mars, but the infrastructure to actually use them really requires an earth space elevator.

How close are we to that? Very. Long enough nanotubes can be grown now. What is still under development is building cables from them with 80% or more of the nanotubes breaking strain.

Oh, Also I (or someone) need to write up what a real earth space elevator will look like. (Turns out when you do a detailed engineering design, it doesn't look much like artists conceptions.)
5 / 5 (1) Dec 18, 2010
How close is close? Cambridge University now has a nanotube fiber with about four times the strength per gram of Kevlar, but: “We have Nasa on the phone asking for 144,000 miles of the stuff, but there is a difference between what can be achieved in a lab and on an industrial level,” says Alan Windle.

No one has ever built a cable that long. Of course, no one has ever had a need for one. (The longest cables today are the undersea telephone cables, which can reach several thousand miles, with some splices. ;-)
5 / 5 (2) Dec 18, 2010
(The longest cables today are the undersea telephone cables, which can reach several thousand miles, with some splices. ;-)
"Some splices" is what we would call a "ridiculously massive understatement".

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