question about google earth sky

a reply to: intrptr

Can Hubble take pictures of Earth?

www.quora.com...

It is what it is. It's like talking about the Space Shuttle going to the Moon - it was never designed to do that.

originally posted by: intrptr
a reply to: SpaceXIsReal

Ground tracking cameras 'slew' missile launches just fine, with video.

Yes, and I have written software specifically to do just that, with video.

Nevertheless, I am able to do that only because the maximum slew rate of my telescope is faster, significantly faster, than the maximum angular rate of motion of the rocket. That is not the case for Hubble, and if my telescope were restricted to 0.1 degrees per second slew rate, I could not do that kind of tracking.

Instead of trying to figure out how it could be done, that is.

I know how it's done, I've done it myself, I've even programmed the software to do it.

originally posted by: intrptr
a reply to: SpaceXIsReal

Ground tracking cameras 'slew' missile launches just fine, with video. Missile warhead homing and guidance do even better at tremendous 'slew'.

Always tickled by all the negative answers. Instead of trying to figure out how it could be done, that is.

Like I said sometime earlier, the way Hubble tracks is by moving its entire self, just like any ground based telescope moves itself to track stars. Hubble achieves this through reaction wheels and sometimes thrusters.

However -- and this is what's important -- since Hubble's observation targets are so far away, there is very little apparent motion between Hubble and the thing it is observing. Therefore, only the minor and slow movements that the reaction wheels (and sometimes thrusters) can provide are enough to allow Hubble to track its targets.

That means that the tracking mechanisms of Hubble cannot achieve the speed necessary to move the entire telescope quickly enough to be able to track the very very close Earth (only a mere 350 miles away) while Hubble itself is moving at 5 miles per second over the earth.

The apparent motion between Hubble and the Earth is just way too fast for the ENTIRE TELESCOPE to be swinging around at the speeds required to clearly image the earth as it zooms under it.

I thing a very broad analogy would be like a ground-based observatory being able to rotate its domed telescoped fast enough to track a bird flying past it 100 meters away. Those ground-based telescopes are not designed to track that fast, and neither is Hubble designed to achieve the speeds required to track the earth 350 miles away spinning under it at 5 miles per second.

originally posted by: intrptr
a reply to: SpaceXIsReal

Ground tracking cameras 'slew' missile launches just fine, with video. Missile warhead homing and guidance do even better at tremendous 'slew'.

Always tickled by all the negative answers. Instead of trying to figure out how it could be done, that is.

Well be tickled by this, the answers are NOT negative in the same way this



should be able to win NASCAR after all it is a car and has 4 wheels.

The Hubble was designed from the start to image distant objects and as stated doesn't need to move fast one of the longest exposures was for 100 hours it needs to be very accurate not quick.

a reply to: wildespace

Originally the shuttle was designed to go to the moon. After it built a space station in earth orbit, it was to shuttle parts and crews to build a similar lunar station as a step to colonizing the moon.

a reply to: Soylent Green Is People

Like I said sometime earlier, the way Hubble tracks is by moving its entire self, just like any ground based telescope moves itself to track stars. Hubble achieves this through reaction wheels and sometimes thrusters.

However -- and this is what's important -- since Hubble's observation targets are so far away, there is very little apparent motion between Hubble and the thing it is observing. Therefore, only the minor and slow movements that the reaction wheels (and sometimes thrusters) can provide are enough to allow Hubble to track its targets.

Thats for long time exposures. For hi speed camera shutters only a short track of the ground target would be needed.

a reply to: wmd_2008

The Hubble was designed from the start to image distant objects and as stated doesn't need to move fast one of the longest exposures was for 100 hours it needs to be very accurate not quick.

Somewhere else I read that each time Hubble was upgraded there was a period of several days(?) where the astronomers had to wait their turn for the Alphabet agencies to finish with Hubble first.

Finish what?

originally posted by: intrptr
a reply to: Soylent Green Is People

Like I said sometime earlier, the way Hubble tracks is by moving its entire self, just like any ground based telescope moves itself to track stars. Hubble achieves this through reaction wheels and sometimes thrusters.

However -- and this is what's important -- since Hubble's observation targets are so far away, there is very little apparent motion between Hubble and the thing it is observing. Therefore, only the minor and slow movements that the reaction wheels (and sometimes thrusters) can provide are enough to allow Hubble to track its targets.

Thats for long time exposures. For hi speed camera shutters only a short track of the ground target would be needed.

But the point isn't how far Hubble would need to track; it's how fast it would need to move while tracking Earth.

We know it can continuously track for a long time. That's one of the advantages of Hubble -- i.e., that it can spend days pointed at a single object and continuously gathering light from that object. That requires days of continuous tracking.

The short-term tracking still can't be done if it needs to move fast for that short term. Hubble doesn't track fast.

originally posted by: intrptr
a reply to: wmd_2008

The Hubble was designed from the start to image distant objects and as stated doesn't need to move fast one of the longest exposures was for 100 hours it needs to be very accurate not quick.

Somewhere else I read that each time Hubble was upgraded there was a period of several days(?) where the astronomers had to wait their turn for the Alphabet agencies to finish with Hubble first.

Finish what?

Could you please find links to that?

I might be wring, but I'd be surprised if "alphabet agencies" would use Hubble as a spy satellite. There are already purposely-built spy satellites that would do a much better job than Hubble.

It should be remembered that while Hubble is a relatively large telescope with relatively high magnification, it's value is NOT in its magnification ability, but rather in the fact that it is (a) above the atmosphere, thus it's images are not subject to atmospheric distortion, and equally important (b) it can stare at a single point in the sky for several hours or days at a time, continuously taking in light.

Hubble can stare at a part of the sky that looks black, but if it stares long enough, it can gather enough photons of light from objects to be able to see objects normally too dim to be seen. Magnification helps, but its this light gathering ability that makes Hubble special.

There are ground based telescopes that have much much higher magnification than Hubble, but they are subject to atmospheric distortion and limited by the fact that daylight comes quite regularly.

That's what Hubble was designed to do. Spy satellites are designed to be able to see things on Earth close up. So spy satellites would do a better job than Hubble if someone wanted to look closely at something on Earth from orbit. I don't think using Hubble for that purpose provides any advantage over using a purposely-built spy satellite.

they can fit the whole earth in a image from the space station and thats 120 miles out lol www.rt.com...

originally posted by: dan121212
they can fit the whole earth in a image from the space station and thats 120 miles out lol www.rt.com...

That's a fish-eye lens, so the Earth in that image is curved more than it really is.

One hint that it is a fish-eye is the way the solar panels looked curved in that image. Those solar panels are actually straight.

This is what Earth looks like from the ISS:

originally posted by: intrptr
a reply to: wildespace

Originally the shuttle was designed to go to the moon.

It wasn't, you misunderstood what you've read.

Q. Can the Space Shuttle fly to the Moon?
A. No, the Space Shuttle is designed to travel in low-Earth orbit (within a few hundred miles of the Earth's surface). It does not carry enough propellant to leave Earth's orbit and travel to the Moon. The Space Shuttle also is not designed to land on the Moon since it lands like an airplane and the Moon has no atmosphere. The Shuttle could be used to carry pieces of Moon or Mars vehicles to low-Earth orbit, where they could be assembled prior to beginning their mission.

www.nasa.gov...

Think about it. The Shuttle's two SRBs are spent and drop off 2 minutes after liftoff. The external fuel tank is all but spent upon reaching the low earth orbit, and also drops off. The only fuel left on the Shuttle Orbiter is for maneuvering in low earth orbit and for slowing down for reentry.

Do you remember how huge Saturn V rocket was? all that gigantic size and fuel capacity, just to get the Command/Service/Lunar Module configuration to the Moon.

originally posted by: intrptr
a reply to: wmd_2008

The Hubble was designed from the start to image distant objects and as stated doesn't need to move fast one of the longest exposures was for 100 hours it needs to be very accurate not quick.

Somewhere else I read that each time Hubble was upgraded there was a period of several days(?) where the astronomers had to wait their turn for the Alphabet agencies to finish with Hubble first.

Finish what?

No doubt from a conspiracy site most spy satellites fly in lower orbits some have mirrors the same size as the Hubble about 2.4 mtr and no they can't read number plates or newspaper headlines.

originally posted by: dan121212
they can fit the whole earth in a image from the space station and thats 120 miles out lol www.rt.com...

May I suggest you start digging a bit deeper before jumping to conclusions, photography is a balck art to some on here so what do you think of this.

Sample Footage Shot with the Ultra Rare Nikkor 6mm f/2.8 that Can See Behind Itself

The field of view of this lens is 220 degrees so it can actually show objects slightly behind the photographer at either side.

Also with regard to Soylent Green Is People post showing the Earth from the ISS here is an image of the exif data



Now from that I can see it was taken using a Nikon D3S a full frame digital slr at 24 mm focal length so wide angle iso 200 at 1/250th of a second at f16 aperture. Even the time and date is shown.

Many of us on here are into photography & astronomy for a long long time.

a reply to: wildespace

It wasn't, you misunderstood what you've read.

Then they lied to us. The whole ISS thing was part of a grand "Colonization" opera fueled by "2001" , written by Clark (who invented satellite communications), to go to the moon.

The shuttle in 2001 ferried people back and forth to the moon. This is what was sold to the American public early on about the real shuttle. Build a space station to assemble or outfit craft to shuttle back and forth to the moon, to build bases as jumping of point to Mars, etc.

Seems they had their sights set a little high or lied, whichever.

I'm sure why they lied is classified, probably so not to tell us the shuttle could also capture 'enemy' satellite tech with a robotic arm and bring back to earth in the cargo bay.

a reply to: Soylent Green Is People

But the point isn't how far Hubble would need to track; it's how fast it would need to move while tracking Earth.

The shutter on the cameras compensate for that. Although designed for deep space viewing, additional upgrades have added to Hubbles capability.

Like everyone keeps beating the bush about, thats classified.

originally posted by: intrptr
a reply to: Soylent Green Is People

But the point isn't how far Hubble would need to track; it's how fast it would need to move while tracking Earth.

The shutter on the cameras compensate for that. Although designed for deep space viewing, additional upgrades have added to Hubbles capability.

Like everyone keeps beating the bush about, thats classified.

Really so what are the specs for the camera, if anyone one is beating about the bush it's you the Hubble was designed to view the universe not the Earth, the Shuttle was never designed to go to the Moon as explained earlier and 2001 was shot mainly in the UK and it's premier was in London in May 1968.The Shuttle in 2001 has NOTHING to do with NASA and the real shuttle was never ever claimed to be transport other than to low Earth orbit.

Over your posts you make claims of what seems to be your agenda with NO backing what so ever.

a reply to: wmd_2008

The Shuttle in 2001 has NOTHING to do with NASA and the real shuttle was never ever claimed to be transport other than to low Earth orbit.

Now thats a disclaimer. Thanks for the official line. What is this, the disinfo desk at NSA?

You prolly weren't even alive before the shuttle, when 2001 was first released.

I was.

Edit: Oh, to your question, the 'streak' photos of earth are taken with the long range cameras to adjust for light. I'm talking about hi speed shutters, the kind they use to capture bullets in flight. You could try and convince me they don't utilize that tech in space, too...

but don't bother.

No, Hubble isn't used to "spy" on Earth....Jesus, what a stupid idea.

Hubble is HUGE and is used for LOW LIGHT objects. It's why it's aperture is so big.

To zoom in on something, you don't need a huge opening and mirror. You need a really big Focal Length.

Hubble is sitting 353 miles above the Earth. It's also a very big object with a lot of inertia due to it's mass.

Want to spy on someone from space? You use a much smaller satellite with cameras (that are not made for low light), and telescopic lens with a very large focal length. You'd also put it just outside the Earth's atmosphere like the ISS (around 180 miles up).

Because you're using a much smaller object (mass and inertia) fast tracking would be easy (much easier than using Hubble).

Since you're taking images of the Earth, which the day side would be like looking directly into the sun for Hubble, you will not need to have very long exposures to capture your images.

Since you do not need a huge aperture (because you don't need to collect low light), and only need very large focal length, you simply use telescopic equipment that is compact, but delivers that type of focal length. Say like a Schmidt Cassegrain or Maksutov Cassegrain type of telescope. Short, compact, but can give you huge focal lengths.

Using Hubble to spy on the Earth would be like using a pair of binocs to read a book you're holding in your hand....wrong thing for the job.

Here's a thread I did about Hubble's resolution power:

www.abovetopsecret.com...

originally posted by: intrptr
a reply to: wmd_2008

The Shuttle in 2001 has NOTHING to do with NASA and the real shuttle was never ever claimed to be transport other than to low Earth orbit.

Now thats a disclaimer. Thanks for the official line. What is this, the disinfo desk at NSA?

You prolly weren't even alive before the shuttle, when 2001 was first released.

I was.

Edit: Oh, to your question, the 'streak' photos of earth are taken with the long range cameras to adjust for light. I'm talking about hi speed shutters, the kind they use to capture bullets in flight. You could try and convince me they don't utilize that tech in space, too...

but don't bother.

WRONG mate went to see it just after launch in the UK with my dad, photography is about capturing light when an object requires many seconds, minutes ,hours or even days the shutter is in BULB mode ie left open for a set time for the kind of images the Hubble is designed for, you really need to think more before you type,

Oh and I have a had an SLR camera first film from the late 70's fully manual and of course now digital so I know plenty about photography