If they thought it would be 200km above the surface, why did they aim the illuminating radar at a point 160km above the pole?
In 2009, a lunar orbiter launched by India went quiet and was never heard from again. Fast-forward eight years and NASA say it's spotted it using an Earth-based radar. The Indian Space Research Organisation's Chandrayaan-1 orbiter was supposed to spend two years on its mission, but after 312 days its communications systems …
So it covered a fairly large part of the expected arc, not the very tip.
My ASCII-art is terrible, but think on a circle and draw a line.
If the line is a true tangent (touches the very edge) to the circle you get one moment, and if you miss a little high you never see anything at all.
If the line crosses slightly inside, you get two chances and if you miss a little high you still see something.
You do realize that the US and other governments routinely track space debris and objects in space, right?
I don't know how small they can track, that's classified. As to covering the north pole, that would be one of the first and most heavily monitored space.
If you can't guess, use your imagination.
Anonymous Coward, why would the North pole of the moon be heavily monitored? What secrets does it hold? Or are you just confusing the Lunar North pole with the Earth's North Pole? It's obvious why NASA (ie the USA) would want to monitor the Earth's North Pole, but not so obvious why the interest in the Moon's north pole (other than to track the Indian Lunar orbiter).
So the spacecraft passes through the beam. I'm not sure how well focussed NASA can keep the beam after travelling 385,000 km. 160km probably means they can just miss the Moon and consequently remove any backscatter from the surface. They should still spot anything orbitting at 200km above the poles, especially when the craft's orbit is end on to the Earth so it will rise and fall through the aim point of the beam.
We had one. Back in 1999.
The problem is that it led to the loss of the moon when the nuclear waste dump it was built to manage went boom and sent the moon out of orbit.
NASA quietly replaced the real moon with a dummy one so no one would notice, but the one you see now is just a flat disc, so there is no base on it.
"As NASA explains, it couldn't simply extrapolate the little orbiter's last-known orbit because the moon is “riddled with mascons (regions with higher-than-average gravitational pull) that can dramatically affect a spacecraft's orbit over time”."
NICE!! I learned some new physics this morning :-) Thank you El Reg!
its more todo with building my navigation system using topology radar to scan for space debris with omni directional pings, and generate 3d models in the 3d star map to be used in the next gen space shuttle
so they would want elite dangerous engine without the game assets, just the 160,000 real time stars from our own galaxy https://www.elitedangerous.com/ - then link up your gyroscopes, and thrust math for 1:1 real time positioning of your craft in space, with a procedurally drawn galaxy stored on DNA and just update the renderer until holograms come along
whats with the thumbs down, its the only way to navigate space, especially if you want to go 256 million MPH with my EM pulse propulsion thrusters, BAE Systems probably have working in fighter jets https://youtu.be/NMMA5KgIvYE?t=2m19s with 0.05 second accerlation to reach 256 million MPH with some megawatt magnets and the repelling force
doubt it, a maglev train uses around 8000Kw to move along at 400mph, and so does the french TGV train, so a jet fighter like BAE, would need less then 0.2MW reactor, and that would still be overkill if you want mach 4, and had a nanotube superconducting forcefield and decent radar system with super computer onboard
and fly from the ground and into space without the need for air for combustion which is'nt happening, and use a power charge to shoot off, or just fly around the world non stop for 10 years at mach 4
Ok, so maybe I'm aging myself because I remember watching these shows when I was a kid.
Too bad I didn't save my models and lunch box from Space 1999. Or Lance Link for that matter.
What made me think about this was that on UFO they had to monitor space around the earth for alien ships...
It would be interesting to know if they determined the orbital speed of the craft by using the doppler shift of the returned signal. Of course, to do that, they'd have to factor in the ground motion of the transmitting and receiving stations, as well as the motion of the Moon (libration and other).
P.S. I'll get my coat. It's the one with the radar detector in the pocket.
A target a few metres across has been found in a circle roughly 100Km in diameter after having had been subjected to unknown gravity forces for 8 years.
From a distance of about 1 light second.
Using a bi-static radar system with antennae about 2300 miles apart.
Sadly it looks like they never did deploy the gravity gradiometer Dr Forward invented
"As a proof-of-concept, the mission scientists had previously used the radar technique to spot NASA's Lunar Reconnaissance Orbiter, a much easier task since that craft's navigators knew precisely where to look."
They still knew more or less where to look, just needing to open up the observation window time for longer.
Looking for unknown unknowns (asteroids) is somewhat harder, which is why we tend to only see them after they've been past and are brightly illuminated by the sun on the way out. (The ones brightly illuminated by the sun on the way in are - of course - relatively easy to see)
Bear in mind that you don't need to have something actually lithobrake to have a really bad day. A series of large bolide airbursts (eg, a disintegrating comet) is arguably worse and has been postulated as having effectively sterilised a large swathe of North America and kickstarted the Younger Dryas period.
they just arnt doing it right, when most are made from iron and not stealth material, asteriods would be easy to pick up with the right setup
if you design a ship right with curves, you just need 2 demi domes center top and bottom, instead of a big ball like a apache helicoptor and other planes
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