Full Version: why aren't any space photos in motion?
why is every space photo just a still photo no vids of anything if i'm stu[id and missing something please tell me and provide a link
Firstly I'm moving this to the Space and Astronomy section as it isn't space news.
Secondly, please explain what you mean. There is plenty of video from space missions and has been since Gagarin. Are you talking about unmanned missions?
Secondly, please explain what you mean. There is plenty of video from space missions and has been since Gagarin. Are you talking about unmanned missions?
QUOTE (lordoblivion777 @ May 21 2008, 04:29 PM) 
why is every space photo just a still photo no vids of anything if i'm stu[id and missing something please tell me and provide a link
We've got plenty of video and film, lord. Apollo has dozens of hours of moving pictures!
Any interests in particular?
i think i might know what your talking about, like when the hubble was taking images of comets making impact with jupiter that was all in pictures, it would have been better to have seen it in video.
A few reasons.
As a rule, things having to do with astronomical objects take a LONG time to happen. Space is big, and at the speeds things move at they take a long time to cover the distances. When you're talking STELLAR scale its only over a period of YEARS that we can see things happen. Like this series of photographs of Barnard's Star moving relative to the more distant other stars (1/360 of a degree per year across the sky, fastest angular motion of a star in the sky) http://en.wikipedia.org/wiki/Image:Barnard2005.gif . Most stellar scale things take WAY longer than that to see though. When we're talking planetary scale it still takes a while for things to happen - here's a timelapse series of photos from one of the voyager probes as it approached Jupiter http://en.wikipedia.org/wiki/Image:790106-...31M_reduced.gif .
The time things take is not the only reason. Often taking astronomical photos means long exposures - you need to collect light for a long time in order to build up enough to make a decent image. As such, taking just ONE frame can take a long time. In addition, when you have data coming back from space telescopes or space probes, the downlink speed and onboard storage capacity is limited and is better spent on high-res images rather than low-res video.
There is, of course, LOADS of video from human orbital spaceflight and the Apollo missions and other satellites looking at the Earth. But as a rule those don't deal with astronomical objects other than the moon.
As a rule, things having to do with astronomical objects take a LONG time to happen. Space is big, and at the speeds things move at they take a long time to cover the distances. When you're talking STELLAR scale its only over a period of YEARS that we can see things happen. Like this series of photographs of Barnard's Star moving relative to the more distant other stars (1/360 of a degree per year across the sky, fastest angular motion of a star in the sky) http://en.wikipedia.org/wiki/Image:Barnard2005.gif . Most stellar scale things take WAY longer than that to see though. When we're talking planetary scale it still takes a while for things to happen - here's a timelapse series of photos from one of the voyager probes as it approached Jupiter http://en.wikipedia.org/wiki/Image:790106-...31M_reduced.gif .
The time things take is not the only reason. Often taking astronomical photos means long exposures - you need to collect light for a long time in order to build up enough to make a decent image. As such, taking just ONE frame can take a long time. In addition, when you have data coming back from space telescopes or space probes, the downlink speed and onboard storage capacity is limited and is better spent on high-res images rather than low-res video.
There is, of course, LOADS of video from human orbital spaceflight and the Apollo missions and other satellites looking at the Earth. But as a rule those don't deal with astronomical objects other than the moon.
As steeler fan has not returned to explain exactly what he means I am going to assume he is talking about images from unmanned missions rather than video from manned ones.
Firstly you have to understand why these missions take images in the first place. There seems to be an impression that NASA is taking pretty pictures for the public. Whilst it is occasionally true that an image is taken for public relations purposes the fact is that most of them are taken to give the maximum scientific returns. The vast majority of images returned from NASA missions would probbly seem quite boring to the casual observer. They are, how ever, incredibly fascinating and informative for the geologists, astronomers, planetary scientists, etc.
As the images are being taken for science they need as much information in them as possible. The higher the resolution of the image the better. To achieve this modern spacecraft take images in a slightly different way to your own digital camera. They take them all in black and white (even the colour ones... I will get to that in a moment). The reason for this is that a black and white CCD (CCD = Charged Coupled Device - the chip that converts light into electrical signals in a digital camera) has considerably better resolution than a colour CCD of the same size. In front of the CCD the space probes camera will be fitted with a filter wheel. This allows only light of a certain wavelength to pass through. To produce a coloured image the camera takes 3 separate images, one through a red filter, one through a blue filter and one through a green filter. These three images are then combined on Earth to produce a colour one.
This filter wheel system also gives another advantage. Many different filters can be used allowing scientists to take photographs in very specific wavelengths. This can help in detecting, for example, specific minerals on the surface of Mars, or specific gases in the atmosphere of Saturn. It also enables the camera to tke images in wavelegths not visible to the human eye. Many of the images returned are infra-red or ultra-violet.
All this makes the camera on board a space probe an incredibly powerful scientific instrument.
That is enough of the background. Now to your question, why do they not return moving images? Well firstly most of the images returned don't need to be moving. If you are taking a photograph of a stationary roc then a still picture is good enough. The real reason however is the amount of information is contained in a moving picture. If you go to a website such as YouTube it soon becomes obvious that even a low quality, very short movie takes far longer to down load than a high quality still picture. This is because a movie has to contain far mor digital information and yet contains far less useful information (it will be at a much lower resolution). This will also be true if you have a digital still camera that takes short video clips, the video will be nowhere near as clear as the still image. The video image takes far more processing power to make and far more bandwidth to transmit. The same is true for a spacecraft.
With a spacecraft it has to transmit, not only the photographs it has taken, but telemetry to tell the ground how it is performing and also the results from all the other scientific instruments on board. It would simply be a waste of valuable bandwidth to transmit video with very low scientific value when high quality stills would be more useful.
Having said that, NASA frequently combines still images to produce movies from its probes. There are plenty of them that I have posted in the Space News forum of this site. I have posted moving images of dust devils and moving clouds on Mars (you will find them in the Mars Exploration Rovers thread). I have posted moving images of the Cloud patterns on Venus taken from the European Venus Express mission. I have posted moving images (or at least links) from New Horizons as at flew past Jupiter and I have posted moving images of Saturn taken by Cassini... and those are just the ones I can remember.
I hope that has answered your question.
Firstly you have to understand why these missions take images in the first place. There seems to be an impression that NASA is taking pretty pictures for the public. Whilst it is occasionally true that an image is taken for public relations purposes the fact is that most of them are taken to give the maximum scientific returns. The vast majority of images returned from NASA missions would probbly seem quite boring to the casual observer. They are, how ever, incredibly fascinating and informative for the geologists, astronomers, planetary scientists, etc.
As the images are being taken for science they need as much information in them as possible. The higher the resolution of the image the better. To achieve this modern spacecraft take images in a slightly different way to your own digital camera. They take them all in black and white (even the colour ones... I will get to that in a moment). The reason for this is that a black and white CCD (CCD = Charged Coupled Device - the chip that converts light into electrical signals in a digital camera) has considerably better resolution than a colour CCD of the same size. In front of the CCD the space probes camera will be fitted with a filter wheel. This allows only light of a certain wavelength to pass through. To produce a coloured image the camera takes 3 separate images, one through a red filter, one through a blue filter and one through a green filter. These three images are then combined on Earth to produce a colour one.
This filter wheel system also gives another advantage. Many different filters can be used allowing scientists to take photographs in very specific wavelengths. This can help in detecting, for example, specific minerals on the surface of Mars, or specific gases in the atmosphere of Saturn. It also enables the camera to tke images in wavelegths not visible to the human eye. Many of the images returned are infra-red or ultra-violet.
All this makes the camera on board a space probe an incredibly powerful scientific instrument.
That is enough of the background. Now to your question, why do they not return moving images? Well firstly most of the images returned don't need to be moving. If you are taking a photograph of a stationary roc then a still picture is good enough. The real reason however is the amount of information is contained in a moving picture. If you go to a website such as YouTube it soon becomes obvious that even a low quality, very short movie takes far longer to down load than a high quality still picture. This is because a movie has to contain far mor digital information and yet contains far less useful information (it will be at a much lower resolution). This will also be true if you have a digital still camera that takes short video clips, the video will be nowhere near as clear as the still image. The video image takes far more processing power to make and far more bandwidth to transmit. The same is true for a spacecraft.
With a spacecraft it has to transmit, not only the photographs it has taken, but telemetry to tell the ground how it is performing and also the results from all the other scientific instruments on board. It would simply be a waste of valuable bandwidth to transmit video with very low scientific value when high quality stills would be more useful.
Having said that, NASA frequently combines still images to produce movies from its probes. There are plenty of them that I have posted in the Space News forum of this site. I have posted moving images of dust devils and moving clouds on Mars (you will find them in the Mars Exploration Rovers thread). I have posted moving images of the Cloud patterns on Venus taken from the European Venus Express mission. I have posted moving images (or at least links) from New Horizons as at flew past Jupiter and I have posted moving images of Saturn taken by Cassini... and those are just the ones I can remember.
I hope that has answered your question.
QUOTE (Waspie_Dwarf @ May 26 2008, 12:24 PM)
I hope that has answered your question.
Well, Waspie...if it didn't answer the question, I have no idea what it would take to do so!
Nicely done...as usual!
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