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Why can a satellite run infrared and other forms of data collecting equipment and stream live results back for the public, but not take photos or video? I am guessing there is never enough room to attach photo or video gathering data equipment on those satellites. As for satellites that do take photos and video, is this because the cameras are all pointed at the Moon and other planets? I do appreciate the detailed photos of Mars and other galaxies, but every once in a while can we rotate that equipment to point back at Earth and snap a big selfie of ourselves?

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    $\begingroup$ You mean like the famous image by Voyager 1? de.wikipedia.org/wiki/Pale_Blue_Dot#/media/… $\endgroup$
    – asdfex
    Commented Jan 14 at 17:12
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    $\begingroup$ It's more about wieght than space. Adding the weight of even a small camera increases the fuel needs significantly. So no one is going to waste money on something with little scientific value, and which can already be done by other craft. $\endgroup$ Commented Jan 14 at 20:20
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    $\begingroup$ You could say the same thing about airplanes could you not? Or cars. $\endgroup$
    – DKNguyen
    Commented Jan 15 at 3:12
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    $\begingroup$ Satellite imagery of the earth is so common that most of us carry around devices that can show different types of it to us within a few moments, for mapping purposes (e.g. Google Maps) and weather information (just about any weather app will show recent satellite imagery of cloud cover), not to mention more specialized applications like wildfire detection, agricultural information, and more. $\endgroup$ Commented Jan 15 at 5:37
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    $\begingroup$ When did you last pack a telescope on your drive to the office, just in case you wanted to look at the Moon in the evening? $\endgroup$
    – Graham
    Commented Jan 15 at 8:06

6 Answers 6

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Why is there never enough room on satellites to hold all the equipment needed?

Welcome to Space Exploration SE!

Because of the time involved from planning until completion of goals at the end of the satellite's design life is long, often a decade or more, and the cost of the entire project, those who put major spacecraft into Earth orbit or into deep space for exploration think in terms of missions rather than satellites.

Spacecraft definitely can -- by design -- hold all the equipment needed for the mission.

Missions have objectives, and anything that increases the risk of failure (more hardware, gizmos, etc.) is looked at as potential sources of unexpected trouble. Engineers and spacecraft designers are getting better at adding things while minimizing incremental risk, but they don't do it by simply screwing on more objects and plugging them into the data pipelline. They have to carefully integrate anything new into the power, data, mechanical and thermal management systems without adding substantial risks of failure to the main mission.

For cameras, instead of adding more of them, what's (more often than you realize) done is that when there is time and low risk to the mission, the spacecraft is turned around and pointed at Earth and the regular cameras are used to take "blue dot" photos of Earth. There are actually plenty of these, but it's hard to find an absolutely complete list.

You may find these helpful or at least interesting

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    $\begingroup$ Indeed, satellites do what they're designed to do. If that requires cameras, they include cameras. If it doesn't require cameras, they don't include cameras. It's not about not having room... it's a matter of not doing things that aren't useful. $\endgroup$ Commented Jan 15 at 4:15
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    $\begingroup$ @SimonGeard yes I agree, though I think it's more about not doing things where the added utility doesn't outweigh the added risk, cost and delay. $\endgroup$
    – uhoh
    Commented Jan 15 at 4:42
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    $\begingroup$ You could extend the answer by adding examples for "unnecessary" cameras on spacecraft. The parachute camera for Perseverance and JunoCam come into my mind. $\endgroup$
    – asdfex
    Commented Jan 17 at 16:18
  • $\begingroup$ @asdfex I just don't have the background to do that properly; you are welcome to make an edit here or add an answer. $\endgroup$
    – uhoh
    Commented Jan 17 at 21:40
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Perhaps there is an assumption that new photos of Earth taken from space would be inspiring, enlightening, and meaningful in some way. That was certainly true of the first photos that were taken, but pictures of Earth from space have been around for decades, so the novelty has somewhat worn off. And as indicated in other answers, photos of Earth continue to be taken, so there wouldn't really be much if any additional inspiration from taking even more of the same type of picture.

There was a brief period of time several decades ago when photos of Earth from space were a big deal. Before the space age people could mostly just guess what the Earth looked like from space. So when the first pictures started to come in there was a lot of interest, even in the early grainy photos like this one from Lunar Orbiter 1 in 1966:

Lunar Orbiter 1 photo of Earth



And especially the 1968 Apollo 8 Earthrise photo:

Apollo 8 Earthrise photo

and the 1972 Apollo 17 Blue Marble photo:

Apollo 17 Blue Marble photo



Note that the modern Deep Space Climate Observatory photo shown in this answer is not really that much different than the Blue Marble photo taken over fifty years ago.

Also assuming that you might be referring to deep space probes, the view of Earth actually diminishes as the distance increases, to the point that Earth appears as merely a "pale blue dot":

Pale blue dot photo

The above photo was taken by the Voyager 1 spacecraft in 1990, and it was certainly inspiring and created a lot of interest at the time, especially because of the attention given to the photo by astronomer Carl Sagan.

However there isn't much new to be seen in newer similar photos taken since then, for example this one taken by Cassini from Saturn in July 2013 didn't seem to have the same public impact as the Pale Blue Dot photo:

Cassini photo



Or this photo of the Earth and Moon from Mercury by the Messenger spacecraft in 2010:

Messenger photo



The Galileo spacecraft got a fairly decent photo of Earth in 1992, but not from Jupiter, its ultimate destination, but during its second flyby of Earth:

Galileo photo

As mentioned in other answers and comments there are multiple reasons for space probe designers to not spend additional resources to take photos that don't support the mission. There just wouldn't be much if any benefit, and probably not too many people would likely be interested in looking at them anyway if they aren't much different than pictures that already exist.

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    $\begingroup$ For what it's worth, the Cassini pale blue dot photo is one of my favorite space photos ever taken, even if it had a smaller public impact. $\endgroup$ Commented Jan 17 at 16:17
  • $\begingroup$ @DarthPseudonym - it's only too bad that the Moon wasn't in the right position when the ring photo was taken. In another photo taken the same day the spacecraft position had apparently changed enough to get the Moon into view, but unfortunately the rings were no longer in the camera field of view by that time. In the ring photo the Moon is technically visible, but only as a barely visible smudge on the right side of the Earth. $\endgroup$ Commented Jan 17 at 18:29
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You seem to have overlooked DSCOVR, which pretty much just stares at our planet.

https://epic.gsfc.nasa.gov/

enter image description here

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We have a large number of sources taking photos of our planet. This includes:

  • low-altitude Earth observation satellites (Landsat, SPOT, Maxar). These take high-resolution photos of a small area at a time. Over time, they photograph the entire planet (although most will skip emtpy ocean, I suspect). Landsat imagery is available for free, others are commercial.
  • Geostationary weather satellites, which take photos of the entire hemisphere every 10 minutes (GOES, Himawari, Meteosat). These images are available freely through meteo agencies (NOAA).
  • every manned mission since Gemini carries cameras. Astronauts on the ISS have taken hundreds of thousands of photos of Earth, which are all over Flickr.
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  • $\begingroup$ There's also low-altitude weather satellites, which photograph (almost) the entire planet twice a day. $\endgroup$
    – gerrit
    Commented Jan 15 at 9:13
  • $\begingroup$ There are multiple constellations of LEO morning birds (satellites that cross the equator before noon local time) and LEO afternoon birds (satellites that cross the equator after noon local time). And then there are spy satellites. $\endgroup$ Commented Jan 15 at 16:28
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In fact, there is always enough room on a satellite for everything it needs, because if it couldn't fit something necessary, it wouldn't be able to go into space. (At least, not without failing very soon after launch, if not before, and achieving very little if its mission.)

If a camera that can take photos of Earth were necessary, it would be kn the satellite already. If taking photos of Earth were something it should be doing, or could be doing, without interfering with its actual purpose, then it would be.

What you're asking is the satellite equivalent of "why doesn't my spoon have a sharp edge for cutting steak?" and has the same answer: because that would make it a knife. It would also make it more dangerous and difficult to use as a spoon. We use a knife for cutting instead and leave the spoon for scooping.

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    $\begingroup$ There is not always enough room on a satellite for everything it needs. The MTG and Metop-SG programmes were therefore split in multiple satellites, because a single satellite couldn't fulfill the complete mission. Also, we have sporks! $\endgroup$
    – gerrit
    Commented Jan 15 at 9:15
  • $\begingroup$ Each satellite had everything it needed. Whether that was necessary for the mission as a whole, is a separate discussion. And sporks are neither a good spoon nor a good fork. @gerrit $\endgroup$
    – Nij
    Commented Jan 15 at 10:08
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I always thought they'd first told Sagan no because they didn't want to spend the fuel to turn it around.

They didn't want to point it at the sun.

And someone had to ad-hoc some code into it, without bricking it from doing what it's still doing, while everyone was getting fired. If you want selfies, then that had better be on the docket from day one.

https://en.wikipedia.org/wiki/Pale_Blue_Dot

Sagan proposed the idea of the space probe taking one last picture of Earth. He acknowledged that such a picture would not have had much scientific value, as the Earth would appear too small for Voyager's cameras to make out any detail, but it would be meaningful as a perspective on humanity's place in the universe.

Although many in NASA's Voyager program were supportive of the idea, there were concerns that taking a picture of Earth so close to the Sun risked damaging the spacecraft's imaging system irreparably.

It was not until 1989 that Sagan's idea was put in motion, but then instrument calibrations delayed the operation further, and the personnel who devised and transmitted the radio commands to Voyager 1 were also being laid off or transferred to other projects. Finally, NASA Administrator Richard Truly interceded to ensure that the photograph was taken. A proposal to continue to photograph Earth as it orbited the Sun was rejected.

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