Power would be the primary reason for the difference in speed to deploy.
My expectation is that chip manufacturing is going to exceed data center capacity to deploy them (especially if Terafab is successful). That orbital compute will be less profitable on a per GPU basis than terrestrial compute in the immediacy, but the volume capable of being deployed to orbit will be greater than the rate of deployment terrestrially creating more gross profit being generated in orbit than on Earth over time.
That over time the allowance for data center construction will reduce as people recognize that compute can be deployed in greater volumes in orbit without land, water, and electrical use.
That the reduced construction of data centers terrestrial will put a pinch on GPU longevity terrestrially that won't exist in orbit. In other words in 6 years when a new rack is producing 500-1000x tokens per MW relative to Vera Rubin the capital efficient process might be to rip GPUs out of a data center every 5 years while orbital compute will only decommission satellites based upon their actual remaining utility, and their utility over time due to model improvements will actually improve rather than reduce.
Two years between Blackwell and Vera Rubin, 10x productivity per MW
Elon announced they are going to use their orbital compute rack design for terrestrial applications. I could easily see them deciding to rip racks out of a data center on Earth every 5 years and launching them into space to extract the last remnants of their usefulness while others are just eating the expense of replacement and/or selling their used compute to SpaceX to be redeployed to space for a second life.
Both SpaceX (Bastrop, TX) and Tesla (Brookshire, TX) are constructing solar manufacturing. Targeting 100 GW production annually each. SpaceX for Starlink/Starmind and Tesla for Robotaxi/Grid/Megapack storage. Tesla is supposedly integrating edge compute into their Megapack products to provide incremental inference, same is potentially going to be done in Robotaxi and maybe Optimus. Would not be surprised to see them do the same for Powerwall and provide compute subsidized whole home energy back up.
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