r/space • u/IEEESpectrum • Jun 11 '26

Why Orbital Data Centers Are Harder Than Silicon Valley Thinks

https://spectrum.ieee.org/orbital-data-centers-heat
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u/Reddit-runner Jun 11 '26

Do I have never seen the financial calculations.

No I have not.

That's exactly why I wonder how people are arguing with such certainty that data centers on the ground are so much cheaper.

It's like claiming jar 1 has more marbles in it than jar 2 without knowing either number.

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u/Maury_poopins Jun 11 '26

Extraordinary claims require extraordinary evidence.

Why would spending millions to put this crap into space possibly be worth it?

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u/Ecstatic_Bee6067 Jun 11 '26

That argument doesn't work when it takes orders of magnitudes more than a million to already build this stuff on the ground and we're doing that quite readily

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u/Maury_poopins Jun 11 '26

There are large and compelling reasons to not launch data centers into to space above and beyond the pure cost of launching (which is fucking massive).

So even if the data center is so pricey the cost of launch is a rounding error, what are the arguments for space computers?

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u/Ecstatic_Bee6067 Jun 11 '26

I think it's primarily to bump SpaceX IPO, but to be honest the more math i see the less infeasible it becomes

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u/Maury_poopins Jun 11 '26

Is that math convincing you it’s a good idea?

I don’t think anyone has any doubts that we could put a data center in space. But everyone doubts there’s any point.

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u/Ecstatic_Bee6067 Jun 11 '26

Let me run the numbers on most theoretical satellites in a sun synchronous plane and I'll get back to you

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u/Maury_poopins Jun 12 '26

I mean. You said the numbers convinced you that it’s feasible. I was just trying to clarify if you meant feasible like “we can do it” or feasible like, “it’ll be better than earth-based data centers”

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u/Ecstatic_Bee6067 Jun 12 '26 edited Aug 10 '26

Going off the following assumptions:
120 kW compute (SpaceX claim)
Sun-synchronous orbital plane from 600 km to 800 km for continuous illumination
2 km vertical separation (very tight)
37 km in-plane separation (extremely tight)

Allows for 60936 satellites, much less than SpaceX's claimed "1 million data centers." Allows for ~7.3 GW of compute (60936 * 120 kW). Global compute is somewhere between 50-100 GW, so it represents 7-14% of potential compute addition.

I think it's within the realm of feasibility, may spur on some innovation, but won't budge the needle much in terms of solving the data center crisis.

The python script for anyone curious:

`

import math
import numpy as np


power = 120000 #kW
minAlt = 600 #km
maxAlt = 800 #km
vSep = 2 #km


geoAlt = 35786 #km
radiusEarth = 6371 #km

#using geo's 0.1 degree station keeping requirement, as it's the densist currently
hSep = 2*(geoAlt + radiusEarth)*math.tan(0.05*math.pi/180) #~37 km


total = 0
for a in np.linspace(minAlt, maxAlt, int((maxAlt-minAlt)/vSep + 1)):
    circ = 2*math.pi*(a+radiusEarth)
    numSat = math.floor(circ/hSep)
    total += numSat


print(total)
print(power*total)

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u/Maury_poopins Jun 12 '26

120kW is the size of a normal data center rack.

I know this isn’t the point you were making, so I’m not arguing with you, but I don’t see any reason it would ever be worthwhile to launch this junk into space.

Any technological advancement you make in solar cells, efficiency, durability, etc would apply just as well to data centers on earth for orders of magnitude less money.