The thread for space cadets!

[hobbsyoyo]

Sorry if this has already been posted, but the moon recently photobombed a full-disc photo session of the Earth -

The Science of How DSCOVR Caught the Moon Photobombing Earth

Al Gore bolted out of bed (in 1998) with a vision of providing “a clearer view of our world,” as he would describe it a few weeks later when he announced the idea during a speech at the Massachusetts Institute of Technology. He challenged NASA to send a satellite to the L1 Lagrange Point, a spot one million miles from Earth in the direction of the sun, where the two bodies’ gravitational pulls are in equilibrium. Once there, Triana (the name then) would create a digital age version of Apollo 17’s iconic “blue marble” photograph by beaming back a continuous real-time view of Earth’s sunlit side. This sight would, Gore hoped, heighten consciousness of the planet’s environmental fragility, and encourage contemplation of how global warming could gravely affect it. For the mission’s name, Gore chose to pay homage to Rodrigo de Triana, the sailor who first spotted North America from one of Columbus’ ships.

More of the article at the link.

 

[Berzerker]

I dont believe comets are all that common, more likely a planet that broke up (which may be a source of comets)

but I'm not privy to the pattern

 

[Kaitzilla]

Sorry if this has already been posted, but the moon recently photobombed a full-disc photo session of the Earth -

The Science of How DSCOVR Caught the Moon Photobombing Earth

More of the article at the link.

That is awesome Hobbs!

Now I finally know what the dark side of the moon looks like. (Pretty plain except for the dark spot top left)

 

[Berzerker]

one explanation for the difference between the near and far sides is that we had a 2nd moon from the giant impact and it more or less joined the far side piling up the crust in a low velocity collision. Later on the moon got slammed by debris during the late heavy bombardment (so did we) and tidally locked in its current position.

if the moon had an ocean the near side would be its home and the far side would be the "continent".

whatever hit the moon around 4 bya was heavy, whatever hit us was heavy.

they think the LHB supplied us with the heavy elements we find in our crust and upper mantle and why we're still so hot.

 

[hobbsyoyo]

I dont believe comets are all that common, more likely a planet that broke up (which may be a source of comets)

but I'm not privy to the pattern

Comets are pretty common AFAIK. There is also growing evidence that most asteroids were once comets that lost their volatiles over time.

Your welcome Kaitzilla!

 

[Berzerker]

Comets are believed to be everywhere based on the relative few we see - they allegedly come from a vast reservoir (Oort Cloud) surrounding the solar system. I dont buy it, the amount of matl out that far could never accrete into a ~billion comets.

As for asteroids, their water content is consistent with formation closer to the sun near the snow line between Mars and Jupiter, so is our water. I believe astronomers may have recently found a comet with heavy water ratios closer to the asteroids, but our small sampling so far shows a more distant origin. Of course if a comet follows a highly eccentric orbit it should gather up water from varying distances from the sun.

 

[CavLancer]

Link to video.

Absolutely hilarious!

At the time it was cutting edge, and Rod Serling got a lot of awards. He broke the ground and the imaginative flicks you see today, if you're luck enough to find one, are built on his work.

Here's an example of the time travel ground he broke. I had to fast forward through all the macho BS character development, that's just the way it was.

https://www.youtube.com/watch?v=r9tnEo-v7kU

He did a comedy routine with Jack Benny...

https://www.youtube.com/watch?v=TyJvMPYHLNo

I'm 57 and this was really something in the 60s and early 70s. Then Star Wars came along and blew things wide open.

 

[hobbsyoyo]

Russia has been sending one its satellites dangerously close to communication satellites, hopping orbits while denying that they're doing anything at all suspicious...

From Russia, Unofficial Assurance about Intent of Lurking Luch Satellite

A mysterious Russian satellite that squeezed next to two Intelsat satellites and alarmed company executives has an “extremely small” chance of a collision, a Russian space expert told state-run media.

Ivan Moiseyev, the head of Russia’s Space Policy Institute, told the Russian news agency RIA Novosti in an Oct. 20 story that “the possibility of a collision or some kind of interference is extremely small.”

The Russian satellite, alternatively known as Luch or Olymp, launched in September 2014 and seven months later moved to a position directly between the Intelsat 7 and Intelsat 901 satellites, which are located within half a degree of one another in geostationary orbit 36,000 kilometers above the equator.

In late September, the satellite moved again, according to an analysis published Oct. 5 by Brian Weeden, technical adviser at the Secure World Foundation.

The satellite has now settled at 24.4 degrees west longitude, right next to the Intelsat 905 satellite at 24.5 degrees west, according to information available on the space tracking website n2yo.com, which republishes U.S. Defense Department data.

Moiseyev said the Luch “is simply a relay satellite, sending signals from spacecraft to Earth, for example from the International Space Station — we have communications problems there — and from one satellite to another.”

“In no way can it be an ‘aggressor,’” he told the state news agency. “Any satellite can make some clumsy maneuvers, but collisions are extremely rare.”

More of the story at the link.

This is almost as bad as the when the US and China shot down their own satellites and created a ton of new orbital debris. And their explanation is extremely flimsy. Sure, it could plausibly be a relay satellite but for the purposes they describe, however there is no reason it needs to go all the way to geostationary orbit to do that. Especially when you consider that most of Russia is above latitudes that GEO satellites can effectively communicate with, it makes no sense. There is a reason why the Russians invented Molniya orbits. It is conceivable that Russia has ground stations nearish to the equator but they still wouldn't have to go to GEO to communicate with the ISS and given how low-altitude the ISS is, I'm not sure that a GEO orbit would even be particularly useful to do that. I could be wrong though.


Plus there is a whole procedure for taking a GEO orbital slot given how congested it is. Countries and companies don't get to just hop around to wherever they want out there because it can disrupt/interfere with the communications of other nations satellites.

I'm fairly certain this is a very sophisticated spy satellite and something of a response to the X-37B which can also hop orbits albeit at a much lower altitude.

 

[illram]

Sorry if this has already been posted, but the moon recently photobombed a full-disc photo session of the Earth -

The Science of How DSCOVR Caught the Moon Photobombing Earth

More of the article at the link.

Why does the Earth look so big in this perspective? I.e. in pics from the moon the Earth looks "moon-sized," here it looks like if you were standing on the moon looking at Earth, the Earth would take up a massive portion of the entire sky.

In other news the Cassini spacecraft will be doing a fly by through one of Enceladus's water jets, at a cozy 30 miles above the moon's surface! This will happen on October 28. It's exciting to me as this will be the lowest altitude flyby of these jets yet and it is meant to confirm whether or not there is hydrothermal activity in the ocean underneath Enceladus's ice.

 

[hobbsyoyo]

Why does the Earth look so big in this perspective? I.e. in pics from the moon the Earth looks "moon-sized," here it looks like if you were standing on the moon looking at Earth, the Earth would take up a massive portion of the entire sky.

You mean like in this photo?

Spoiler :

I really don't know to be honest. Here's hoping uppi will show up soon.

In other news the Cassini spacecraft will be doing a fly by through one of Enceladus's water jets, at a cozy 30 miles above the moon's surface! This will happen on October 28. It's exciting to me as this will be the lowest altitude flyby of these jets yet and it is meant to confirm whether or not there is hydrothermal activity in the ocean underneath Enceladus's ice.

Awesome! It's really cool that they are able to re-purpose the science instruments on that spacecraft to do things they didn't imagine doing when they launched it.


____________________

Declassified: The NRO’s Abandoned Plans for a Manned Spy Satellite

Spoiler :

The USAF/NRO once planned on building a super-Gemini to spy on the Ruskies. It was a pretty cool concept but they cancelled it because unmanned satellites proved much cheaper and more effective.

 

[Bootstoots]

Why does the Earth look so big in this perspective? I.e. in pics from the moon the Earth looks "moon-sized," here it looks like if you were standing on the moon looking at Earth, the Earth would take up a massive portion of the entire sky.

The Earth should look quite a bit bigger from the Moon than the Moon does from the Earth, but it still wouldn't be large enough to come close to filling up the entire sky. The Moon is only about 0.5 degrees across in angular diameter. The diameter of the Earth is about 12700 km, and that of the Moon is about 3500 km, so the Earth should be something like 0.5 degrees * 12700/3500 = 1.8 degrees across. The whole sky is 180 degrees across, so it's only taking up 1% of the angular diameter of the whole sky.

The spacecraft that took this picture is at Lagrangian point L1, 1.5 million km away, which is about 4 times the radius of the Moon's orbit. The Moon is in front of the Earth, so Earth is about 4 Moon orbit radii away while the Moon is 3 radii away. Because the Moon is closer, it actually appears a bit larger than if they were side-by-side, but the Earth has ~3.6 times the physical diameter so it still appears much larger (by a factor of ~3.6*3/4 = 2.7) than the Moon.

 

[hobbsyoyo]

Oh and I just thought this: the image is probably cropped so that the Earth fills much more of the frame rather than having a huge amount of black background in the photo.

 

[Thorgalaeg]

Russia has been sending one its satellites dangerously close to communication satellites, hopping orbits while denying that they're doing anything at all suspicious...

From Russia, Unofficial Assurance about Intent of Lurking Luch Satellite

More of the story at the link.

This is almost as bad as the when the US and China shot down their own satellites and created a ton of new orbital debris. And their explanation is extremely flimsy. Sure, it could plausibly be a relay satellite but for the purposes they describe, however there is no reason it needs to go all the way to geostationary orbit to do that. Especially when you consider that most of Russia is above latitudes that GEO satellites can effectively communicate with, it makes no sense. There is a reason why the Russians invented Molniya orbits. It is conceivable that Russia has ground stations nearish to the equator but they still wouldn't have to go to GEO to communicate with the ISS and given how low-altitude the ISS is, I'm not sure that a GEO orbit would even be particularly useful to do that. I could be wrong though.


Plus there is a whole procedure for taking a GEO orbital slot given how congested it is. Countries and companies don't get to just hop around to wherever they want out there because it can disrupt/interfere with the communications of other nations satellites.

I'm fairly certain this is a very sophisticated spy satellite and something of a response to the X-37B which can also hop orbits albeit at a much lower altitude.

GEO is becoming an unvaluable resource, much more than any pice of land i would say. It is not difficult to think on future international conflicts or even wars because GEO. If i remember correctly, some decades ago equatorial countries tried to claim sovereignty over the GEO legs above its territory. Such claims were desestimated by United Nations of course.

 

[uppi]

Oh and I just thought this: the image is probably cropped so that the Earth fills much more of the frame rather than having a huge amount of black background in the photo.

Yes and no. A camera lens maps angles of incoming light to positions on the sensor. This mapping is defined by the properties of the optics and during the design process you can choose how exactly angles are converted to position.

Now, as your link explains, that camera was built with the sole purpose of imaging earth from a certain distance. Therefore, the designer of that lens chose the magnification just right, so that the image of the earth fills the sensor almost entirely and all light coming from other angles (not that there is much) does not hit the sensor. So in a way, that image was cropped, but by the lens design and not by whoever evaluated that image.

In other words: Never confuse the picture of a camera with what you would be seeing if you were standing at the same position. You can design a camera in such a way that it maps light similar to how the eyes do, but you can also design it in a different way. If you were standing (well, falling? orbiting?) at the same position as the camera, your eyes would see earth smaller as they would on the moon, but this camera is not an eye.

 

[ori]

So a comet consisting in small parts of ethanol...

Like a roving interplanetary cocktail bar, a comet is carting around booze and sugar.

 

[Ajidica]

Declassified: The NRO’s Abandoned Plans for a Manned Spy Satellite

Spoiler :

The USAF/NRO once planned on building a super-Gemini to spy on the Ruskies. It was a pretty cool concept but they cancelled it because unmanned satellites proved much cheaper and more effective.

Not sure if you have seen it, but PBS/NOVA had a neat documentary on American and Soviet manned spy satellites.
http://video.pbs.org/video/980042464/

 

[PlutonianEmpire]

Sorry if this has already been posted, but the moon recently photobombed a full-disc photo session of the Earth -

The Science of How DSCOVR Caught the Moon Photobombing Earth

More of the article at the link.

Since DSCOVR will more or less keep a constant/near constant eye on Earth, do you think they might eventually create a timelapse similar to the .gif, spanning a whole year? It would be really cool to see not just the seasonal changes, but the actual apparent orientation of the Earth change with it. Slowly seeing each pole shift into, and then out of view, over the course of a year would look pretty neat indeed.

 

[warpus]

During the eclipse

 

[hobbsyoyo]

Not sure if you have seen it, but PBS/NOVA had a neat documentary on American and Soviet manned spy satellites.
http://video.pbs.org/video/980042464/

I hadn't seen it until you posted the link. Thanks for sharing, it was a really cool documentary!

Since DSCOVR will more or less keep a constant/near constant eye on Earth, do you think they might eventually create a timelapse similar to the .gif, spanning a whole year? It would be really cool to see not just the seasonal changes, but the actual apparent orientation of the Earth change with it. Slowly seeing each pole shift into, and then out of view, over the course of a year would look pretty neat indeed.

Yes, this should happen.

During the eclipse

Super cool video!

 

[hobbsyoyo]

More cool photos of last year's Antares launch failure here.