[Starlink] AI IN SPACE: Post from Elon Musk (@elonmusk)

[Starlink] AI IN SPACE: Post from Elon Musk (@elonmusk)

[Hesham ElBakoury]

Elon Musk (@elonmusk) posted at 11:39 AM on Wed, Nov 19, 2025:
https://t.co/x4nowlSiSa
(https://x.com/elonmusk/status/1991229881447858627?s=03)

Hesham

[Starlink] Re: AI IN SPACE: Post from Elon Musk (@elonmusk)

[Vint Cerf]

he makes a good point about the availability of power in space.
Are their limitations owing to being in Earth's shadow an appreciable part
of many orbits? Would location near Lagrange points help?

v


On Thu, Nov 20, 2025 at 2:46 AM Hesham ElBakoury via Starlink <
starlink@lists.bufferbloat.net> wrote:

> Elon Musk (@elonmusk) posted at 11:39 AM on Wed, Nov 19, 2025:
> https://t.co/x4nowlSiSa
> (https://x.com/elonmusk/status/1991229881447858627?s=03)
>
> Hesham
> _______________________________________________
> Starlink mailing list -- starlink@lists.bufferbloat.net
> To unsubscribe send an email to starlink-leave@lists.bufferbloat.net
>


-- 
Please send any postal/overnight deliveries to:
Vint Cerf
Google, LLC
1900 Reston Metro Plaza, 16th Floor
Reston, VA 20190
+1 (571) 213 1346


until further notice

[Starlink] Re: AI IN SPACE: Post from Elon Musk (@elonmusk)

[Kenneth Porter]

It's all geometry. Recall that the Earth is 8000 miles in diameter. LEO 
is just a few hundred  miles above the surface, so you'll spend half 
your orbit in shadow. If you put the satellite much higher and in a 
tilted orbit, it spends much less time in shadow. Much like how the 
Earth and Moon rarely eclipse each other.

Lagrange points L4 and L5 are advantageous because the orbits are 
stable, compared to the other Lagrange points. The downside is that 
they're 250,000 miles away, in the same orbit as the moon. One leads the 
moon by 60 degrees while the other lags it. They'd be good if you used 
lunar material to build your satellites, but bad if you raise the 
material from the Earth. A geosync orbit is about 22,000 miles above sea 
level (26,000 radius) but do you need to maintain position over the same 
point on the surface?

A medium Earth orbit (MEO) is probably a good compromise for 
Earth-sourced materials.

Low Earth orbit is crowded but cheap and suffers the shadow problem. 
Probably not a good place.

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

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

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

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

[Starlink] Re: AI IN SPACE: Post from Elon Musk (@elonmusk)

[David Lang]

sun synchronous orbits are in sunlight 100% of the time at any altitude.

David Lang

On Thu, 20 Nov 2025, Kenneth Porter via Starlink wrote:

> Date: Thu, 20 Nov 2025 09:03:00 -0800
> From: Kenneth Porter via Starlink <starlink@lists.bufferbloat.net>
> Reply-To: Kenneth Porter <shiva@sewingwitch.com>
> To: starlink@lists.bufferbloat.net
> Subject: [Starlink] Re: AI IN SPACE: Post from Elon Musk (@elonmusk)
> 
> It's all geometry. Recall that the Earth is 8000 miles in diameter. LEO is 
> just a few hundred  miles above the surface, so you'll spend half your orbit 
> in shadow. If you put the satellite much higher and in a tilted orbit, it 
> spends much less time in shadow. Much like how the Earth and Moon rarely 
> eclipse each other.
>
> Lagrange points L4 and L5 are advantageous because the orbits are stable, 
> compared to the other Lagrange points. The downside is that they're 250,000 
> miles away, in the same orbit as the moon. One leads the moon by 60 degrees 
> while the other lags it. They'd be good if you used lunar material to build 
> your satellites, but bad if you raise the material from the Earth. A geosync 
> orbit is about 22,000 miles above sea level (26,000 radius) but do you need 
> to maintain position over the same point on the surface?
>
> A medium Earth orbit (MEO) is probably a good compromise for Earth-sourced 
> materials.
>
> Low Earth orbit is crowded but cheap and suffers the shadow problem. Probably 
> not a good place.
>
> https://en.wikipedia.org/wiki/Medium_Earth_orbit
>
> https://en.wikipedia.org/wiki/Lagrange_point
>
> https://en.wikipedia.org/wiki/Geosynchronous_orbit
>
> https://en.wikipedia.org/wiki/Low_Earth_orbit
>
>
> _______________________________________________
> Starlink mailing list -- starlink@lists.bufferbloat.net
> To unsubscribe send an email to starlink-leave@lists.bufferbloat.net
>

[Starlink] Re: AI IN SPACE: Post from Elon Musk (@elonmusk)

[Kenneth Porter]

--On Thursday, November 20, 2025 11:50 AM -0700 David Lang <david@lang.hm> 
wrote:

> sun synchronous orbits are in sunlight 100% of the time at any altitude.

Wow, I learned something new! Thanks! That's quite a clever setup.

https://en.wikipedia.org/wiki/Sun-synchronous_orbit

[Starlink] Re: AI IN SPACE: Post from Elon Musk (@elonmusk)

[David Lang]

Michael Richardson wrote:

> Which is to say, they satellite is always getting heated from one side :-)
>
> For non-sun synchronous LEOs, does the dark time help with radiant cooling?
> I assume some satellites' cooling profile are designed around the assumption that they
> will be dark for a portion of the orbit?

when you are in sunlight, you can radiate in 5 directions (except the tiny 
slices that face the earth and moon)

when you are not in sunlight, you have to operate on battery power

if you are in a 90 min low orbit, you spend just over 33 min in shadow each 
orbit.

When you are in geosynchronous orbit (24 hour orbit) you only end up in the 
shadow for a few months each year (late February to mid-April and late August to 
mid-October) and then only for about 70 min out of each 1440 min orbit

so no, satellites do not rely on being in the shadow for their cooling

David Lang

[Starlink] Re: AI IN SPACE: Post from Elon Musk (@elonmusk)

[tom]

Just to speculate out of my depth:

Although the first generation of orbiting and probably lunar datacenters
will probably be made from components which were designed for use on earth,
the second generation may not be.

Waste heat comes mainly from electrical resistance. But there is little
waste heat with superconductivity. Is it possible to design circuits meant
for use only in space which are largely superconducting so that both the
energy demand is way down and there is less heat to dissipate? 

Fiber is a wave guide in a scattering atmosphere. Do we need fiber between
lasers and receptors in space for short distances when we don't need the
signal to go around corners? Fiber adds impedance and distortion and
increases the transmit power needed.

Is there a battery-like chemical reaction powered by extra heat which
reverses in shade and uses the chemically-stored heat to generate
electricity?

How much better (or differently designed) can chips be when manufactured
without either gravity or contamination?

Fun to think about what constraints will be gone and what that might mean.

-----Original Message-----
From: David Lang via Starlink <starlink@lists.bufferbloat.net> 
Sent: Thursday, November 20, 2025 3:12 PM
To: Michael Richardson <mcr@sandelman.ca>
Cc: David Lang <david@lang.hm>; starlink@lists.bufferbloat.net
Subject: [Starlink] Re: AI IN SPACE: Post from Elon Musk (@elonmusk)

Michael Richardson wrote:

> Which is to say, they satellite is always getting heated from one side 
> :-)
>
> For non-sun synchronous LEOs, does the dark time help with radiant
cooling?
> I assume some satellites' cooling profile are designed around the 
> assumption that they will be dark for a portion of the orbit?

when you are in sunlight, you can radiate in 5 directions (except the tiny
slices that face the earth and moon)

when you are not in sunlight, you have to operate on battery power

if you are in a 90 min low orbit, you spend just over 33 min in shadow each
orbit.

When you are in geosynchronous orbit (24 hour orbit) you only end up in the
shadow for a few months each year (late February to mid-April and late
August to
mid-October) and then only for about 70 min out of each 1440 min orbit

so no, satellites do not rely on being in the shadow for their cooling

David Lang
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[Starlink] Re: AI IN SPACE: Post from Elon Musk (@elonmusk)

[David Lang]

tom@evslin.com wrote:

> Just to speculate out of my depth:
>
> Although the first generation of orbiting and probably lunar datacenters
> will probably be made from components which were designed for use on earth,
> the second generation may not be.
>
> Waste heat comes mainly from electrical resistance. But there is little
> waste heat with superconductivity. Is it possible to design circuits meant
> for use only in space which are largely superconducting so that both the
> energy demand is way down and there is less heat to dissipate?

not for the processing, and even for power transmission, you have to couple the 
very cold (liquid nitrogen temp) superconductors to the semiconductor circuits 
that are generating all the heat. The vast majority of the heat is generated by 
the processing, not the power transmission

batteries also don't work when they get really cold (which is why solar powered 
lunar landers frequently don't 'wake up' when they get light again after the 2 
week long night)

> Fiber is a wave guide in a scattering atmosphere. Do we need fiber between
> lasers and receptors in space for short distances when we don't need the
> signal to go around corners? Fiber adds impedance and distortion and
> increases the transmit power needed.

No, free space lasers work great in space, so laser based interconnects can help 
(they are also being experimented here on earth, with and without fibers.

However, as things heat and cool, they move, so the laser alignment may cause 
more grief than you expect.

> Is there a battery-like chemical reaction powered by extra heat which
> reverses in shade and uses the chemically-stored heat to generate
> electricity?

not that works well at the temperatures needed for the moon. If there was, the 
lunar landers would use it so that they can live more than 2 weeks after the 
many millions of dollars that are spent building and launching them.

> How much better (or differently designed) can chips be when manufactured
> without either gravity or contamination?

gravity is a good question (they have been doing testing in the ISS)

eliminating contamination is a large part of the cost of building a chip fab, 
but it gets amatorized over all the chips that are built, so if you can create 
chips in space the savings in launch costs will probably be more than the 
savings in fab costs (at least, until Starship scales up, dropping the cost from 
$1000/pound to $10/pound will change the economics a smidge :-) )

David Lang

[Starlink] Re: AI IN SPACE: Post from Elon Musk (@elonmusk)

[Kenneth Porter]

Another interesting product you could make cheaply in microgravity:

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

Get the metal from lunar ore, smelt it in orbit with reflectors, and 
create a big reentry sled out of it. Drop it in an ocean, tow it to 
shore, and chop it up for your applications.

[Starlink] Re: AI IN SPACE: Post from Elon Musk (@elonmusk)

[J Pan]

https://en.wikipedia.org/wiki/Dyson_sphere ?
--
J Pan, UVic CSc, ECS566, 250-472-5796 (NO VM), Pan@UVic.CA, Web.UVic.CA/~pan

On Wed, Nov 19, 2025 at 11:46 PM Hesham ElBakoury via Starlink
<starlink@lists.bufferbloat.net> wrote:
>
> Elon Musk (@elonmusk) posted at 11:39 AM on Wed, Nov 19, 2025:
> https://t.co/x4nowlSiSa
> (https://x.com/elonmusk/status/1991229881447858627?s=03)
>
> Hesham
> _______________________________________________
> Starlink mailing list -- starlink@lists.bufferbloat.net
> To unsubscribe send an email to starlink-leave@lists.bufferbloat.net

[Starlink] Re: AI IN SPACE: Post from Elon Musk (@elonmusk)

[Kenneth Porter]

Alas, both the Dyson Sphere and the simpler Ringworld are unstable and 
will drift into the object they orbit. Some pesky math majors proved that.

(I've been a space nut and a hard SF fan since the 60s. I so wish more 
people understood how orbits work, but our science education system is 
poor and our space movies lie about how orbits work. So far, the best 
I've seen are 2001, Babylon 5, and The Expanse. Everyone else does WWII 
dog fighting in space, as if it had an atmosphere. A great tool for 
learning it is Kerbal Space Program, a construction game for building 
and testing spacecraft.)