Posted on 01/17/2018 9:22:59 PM PST by BenLurkin
On February 4, an asteroid called 2002 AJ129 is due to slip past Earth. It is between 1600 and 4000 feet across, according to NASA's Center for Near Earth Object Studies, but there's no chance it will make impact—NASA has calculated it will remain 2.6 million miles away.
That still makes it what astronomers call a "potentially hazardous asteroid," thanks to its size being more than about 500 feet across and an orbital path that carries it within about 4,650,000 miles of Earth.
But while they're confident we won't all go the way of the dinosaurs, scientists do want to keep an eye on the space rock—and they'll do so with the Goldstone Radio Telescope in California. That is one of the U.S.'s two high-powered radar astronomy facilities, along with the Arecibo telescope in Puerto Rico.
There are a whole host of asteroid characteristics scientists would like to understand—their size, their shape, how quickly they rotate, what they look like on the inside, and the like. That's where radar astronomy comes into play. "We can actually learn a great deal about objects and start to answer some of these questions using radar observations," Lance Benner, a NASA astronomer who uses radar technology to study passing asteroids, told Newsweek.
Most astronomy is passive, simply gathering signals that space produces naturally. But radar astronomy creates its own signal with the much more powerful cousin of the radar systems used to direct traffic at airports or to tell weather forecasters when to expect rain. It's an imaging technique that blasts a powerful beam of radio waves, which are very long waves of light, out into space to bounce off an object.
(Excerpt) Read more at newsweek.com ...
2.6 million miles. Ooooooh so close. I wonder if 2 million miles would be almost a direct hit.
****ed right! And “Diplomacy: sometimes you just have to punch an alien in the face.”
See inside it ...??
Maybe NASA has this guy on the case ......
But will Bigfoot see the asteroid?
Is it known to the state of California to cause cancer or birth defects?
Sensationalism. 10ld is not close.
There is a 30m object coming within 0.15ld in October (2012 TC4) That is close.
Save assumption is it’s known to the state of California to cause cancer or birth defects until proven otherwise.
The Mayans knew!
On Alice Cooper’s 70th birthday.
Coincidence?
I think not.
/welcome to your nightmare
I am Kirok!
Only if it happens to be updating its Facebook status, at the time.
“NASA has calculated it will remain 2.6 million miles away”
“path that carries it within about 4,650,000 miles of Earth. “
Am I the only one that sees some inconsistency here? What’s 2 million miles difference between friends?
It’s a lot easier to determine an orbit than size, and the error in the orbit is many, many times the dimension of the asteroid, but not many times the size of earth. Even in the most powerful telescopes this object’s image will not subtend more than a few pixels at closest approach.
Radar has much poorer angular resolution than optics, but it’s range resolution is independent of range, if the signal to noise ratio is high enough. Determining an orbit requires solving for six parameters equivalent to three position variables (x, y, z) and three velocity variables (dx/dt, dy/dt, dz/dt), or equivalently, six Keplerian elements. Given six [linearly independent] measurements of the subject’s range, one can solve for orbital parameters within the limitations of the observational accuracy. More measurements provide increased accuracy by averaging effects of measurement “noise”. In principle, three optical measurements provide the same information, but the accuracy of optical measurements at these ranges is on the order of several kilometers, radar as small as a meter.
Taking measurements over a long temporal baseline improves velocity estimates. Errors in position are the same, but the denominator, “delta time” is much larger.
One very slick technique for measuring the dimensions of an asteroid is optical occlusion timing. If an asteroid happens to throw past in front of star and cast a tiny shadow on earth, the moving shadow reveals the exact dimensions of the asteroid, whether it is a binary (a surprising fraction are) and gives highly precise position information for orbital refinement. If a number of observers on earth can reliably time the onset and end of occlusion, their observations can be processed to make high resolution silhouettes. When the shadow falls across North America during good weather there are a number of amateurs who have the required instrumentation, talent, time and enthusiasm to make these measurements.
Land a couple of ion engines then use the engines to:
1) slow it down
2) alter the course
3) spin till it destructs
Could cause a generation landslide.
No. There is an object in earth orbit with about the same period as the moon, about 27 days (sidereal month). No one is quite sure what it is or where it came from but spectrographic studies show that it has the same reflectivity as the NASA white paint from the 1970's. Most likely an Apollo booster rocket, but again, no one expected it.
Optical spectroscopy may not be able to definitely identify the surface composition of an object, but it can rule a lot of things out.
You'd just be spinning the chunk you broke off. The rest of it would sail on.
It may be that its orbit comes within 2.6 million miles of earth’s orbit, and hence it “will” stay 2.6 million miles away for the foreseeable future, but will approach to within 4,650,000 miles on this particular pass?
Does seem to be a contradiction, I agree.
RE: “inconsistency” or “contradiction”
My comprehension of paragraphs one and two above. . .
Paragraph 2: Defines the size and distance of what astronomers generally call a “potentially hazardous asteroid,” = diameter greater than 500 feet & closer than 4,650,000 miles from Earth.
This asteroid exceeds the defined size and is closer than the defined distance, thus it is a “potentially hazardous asteroid.”
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