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

Question

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?

Answer 1

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

• How many spacecraft have taken a "Pale Blue Dot" type photo of the Earth from beyond cis-lunar space?
• Do Starlink satellites have cameras?
• Does SpaceX use any of Falcon-9's camera data for engineering or status information, or are they "just for PR"?
• Biggest periscope camera that could fit inside a Starlink satellite; how thick are they?
• If all Starlink satellites had phone tier cameras & simple scopes, could images processed by their super-resolution imaging network be competitive?
• How will Perseverance's selfie skills compare to Curiosity's? Will it have any additional selfie-related capabilities?
• How did the JWST take a selfie?
• How common is it for spacecraft to have "selfie" capability?

Answer 2

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:

And especially the 1968 Apollo 8 Earthrise photo:

and the 1972 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":

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:

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

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:

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.

Answer 3

You seem to have overlooked DSCOVR, which pretty much just stares at our planet.

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

Answer 4

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.

Answer 5

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.

Answer 6

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.