I’ve heard that back in 1960, international radar stations detected a large satellite in orbit around the Earth. The satellite weighed an estimated fifteen tons and was in a polar orbit - characteristics that were beyond the launch capabilities of any country. Both the United States and the Soviet Union panicked at the possiblity that the other side had been able to take such a lead in space, especially in secret. But neither side ever took credit for the satellite and neither demonstrated the capability of launching such a satellite for years afterwards. So the satellite was codenamed “Black Knight” and there was never any explanation of what it was.
My problem is that the information I’ve heard about the Black Knight is that it’s found in various conspiracy books. I find this stuff entertaining but not authoritative. These writers are willing to consider theories involving aliens or the Illuminati as reasonable explanations but I’m looking for something a little more rational.
One obvious explanation is that the thing is completely fictitous; that nothing was ever detected and the reports of such are just an urban legend. Another possibility is that it was just a “ghost” image detected by a radar glitch and there was nothing actually up there.
Never heard of it, but it seems dubious because there’s no way to measure the mass of a satellite from the ground. You can estimate the physical size, but using radar alone, I think it’s impossible to distinguish between a 15-ton space station and a huge balloon.
I’ve not heard of this mega satellite from 1960 but I would be surprised if the US (or anybody with any knowledge of rocketry) called it Black Knight. Too much chance of confusion with an existing programme.
Black Knight was the name of a British rocket designed to test ballistic re-entry vehicles that ran from '58 to '65.
It was a badly damaged satillite that had it’s extermities removed, yet claimed that it was only a “flesh wound”. It’s last communication was “come back here you coward and I’ll bite your legs off”.
Seems interesting the government would report something like an unknown satellite at all. What can the average person do about it? Seems more like a setup to publish the followup story and show how great we were at detecting space objects.
In the derivation for geosynchronos orbit the mass of the satalite ends up on both sides of the equations and cancles out. To keep a heavier object in geosynchronos orbit you need a greater pulling force to keep the heavier object from flying off on a tangent. As the object is heavier, that greater force is provided by the increased gravitational attraction between the earth and the heavier satalite. Everything drops out to be on a per kilogram basis.
Another way to look at is , is it 1 satalite with 1000kg mass, or 1000 satalites joined togeather with a 1 kg mass each. They all have a geosynchronos orbit at the same altitude.
Kepler’s laws of planetary motion are mass independent. The implicit assumption here is that the mass of the primary is vastly more than the mass of the object in nominal orbit, which is a reasonable assumption for artificial satellites orbiting the Earth (and even works well enough with Luna orbiting Earth to within about three or four decimal places).
However, contrary to the observation of scr4, it is theoretically possible to discern some idea of the mass of a satellite via the effect of gravitational variance on its orbit. Differences in local density in the crust are sufficient to cause slight perturbations in the orbit of a satellite, though even today it would require several very precise position measurements along the orbit to make any reasonable guesses about the mass; this is certainly beyond the capability in 1960, as were polar orbit launches with existing launchers (Soviet R-7 and American SM-65 Atlas and Titan I). So I’d have to agree with scr4 that from any practical standpoint the stated facts of this alleged satellite are at odds with known capabilities of the day.
Why would the perturbation be dependent on the mass of the satellite? You’re still talking about variations in the gravitational field.
Although come to think of it, for a low-orbit satellite it may be possible to measure the decay rate of the orbit, and estimate the surface/volume ratio of the satellite. (The orbit decay is caused by the tiny amount of air that’s present in low orbit, so it would be dependent on the ratio between cross-sectional area and mass.) And you can look at satellites through optical telescopes to estimate its size (cross-sectional area), and combine these measurements to get an estimate of mass. Not sure how accurate that would be though.
To determine an object’s mass from observations of orbits, you need to measure its effects on the orbits of other things. So it’s easy, for instance, to determine the mass of the Sun, since it has a significant effect on the orbits of the planets, or to determine the mass of the Earth, since it has a significant effect on the orbit of the Moon. But man-made satellites are small enough and far enough from other things that their effects on the orbits of other objects would be miniscule, and detectable only (if at all) via extremely precise measurements.
Titan I? I was unware that the Titan I (a early cryogenic fueled version of the storable propellent Titan II ICBM) was ever used as a satellite launcher. If that isn’t a typo, cite please.
Anyway, orbital mechanics can tell you the product of two masses orbiting around a common center, but since the Earth’s mass is in the sextillions of tonnes, you aren’t going to be able to detect the satellite’s mass directly.
Not the product, the sum. But otherwise your point is correct. The uncertainty in our knowledge of the mass of the Earth is far greater than the mass of any satellite we’ve launched.