Lumen Orbit has raised more than $10 million to deploy data centers in space, TechCrunch reports.

The Y Combinator startup plans to deploy data centers in space for training AI models, and claims a pathway to gigawatt capacity. It plans to launch a demonstration satellite in 2025 as part of Nvidia’s Inception program.

Lumen Orbit
– Lumen Orbit

In a whitepaper, the company said that space-based data centers would be able to utilize high-intensity 24/7 solar power, without worrying about day/night cycles or atmospheric losses.

This, they claim, would give the facility energy at a cost 22 times lower cost than today’s energy prices.

It would also require large radiators to dissipate heat, coming in at roughly half the size of the corresponding solar arrays. "Within the compute modules, either direct-to-chip liquid cooling or potentially two-phase immersion cooling is required to achieve high power densities and a space-efficient rack setup," the paper states.

Heat will be moved from the modules to the radiators by "several cooling loops, using two-phase systems where practical. "We estimate we can achieve comparable PUE to state-of-the-art hyperscale terrestrial data centers."

The company makes bold claims about cost in its paper - saying that a 40MW data center on land running for a decade would cost $140m to power, $7m to cool, and $20m for backup infrastructure, for a total of $167m.

By contrast, it argues it would take $2m to deploy its space solar arrays, $5m to launch the compute module, and $1.2m for radiation shielding, for a total of $8.2m.

That calculation relies on a number of presuppositions, including the fact that it would require the largest solar deployment in space yet. The current frontrunner, the ISS' 34,918 sq ft deployment, is capable of generating 120kW.

Lumen's much larger installation, meanwhile, appears to rely on calculations from a Longi whitepaper that note solar cells cost about $0.03/watt to manufacture.

However, that does not include any other costs of a solar array, with space-based cells in particular requiring protection from the harsh environment. The European Space Agency notes that a bare cell would degrade in just a few days, and states that most space-based arrays are covered in a 0.1 mm sheet of glass - which costs more, could increase weight substantially, and impacts the performance of the cells.

Given the environment, the cheapest solar modules may not be the best, and the company would likely have to overprovision or have further launches to offset the degradation they will experience after years of 24/7 use and radiation exposure.

The largest unknown is that of launch costs. The company relies on a $30/kg launch cost to reach its $8.2m figure, but costs are currently around $1,520/kg on the Falcon Heavy.

SpaceX's Starship is expected to dramatically change that, with the company recently successfully catching its booster rocket as part of ongoing tests.

Should Starship be successful, costs could fall to $150/kg for single-use rockets. If both the booster and upper stage can be reusable, and Starship manufacturing costs drop, that could reach the $10-30/kg figure. But such an eventuality is not guaranteed, nor is a clear timeline predictable.

Lumen also mentions that their large spaceship would legally require "highly responsive spacecraft maneuverability for collision avoidance," costs of which do not appear to be included.

While elsewhere in the document the company admits that hardware will fail (and will become outdated quickly, particularly for AI training), and that modules can be replaced, the $8.2m number takes into account just one single launch.

Without human maintenance, failures could be higher in space than on Earth, requiring even more launches than just upgrades - and as the whole module would have to be replaced, a small percentage of failures could doom the entire module.

A render of the system shows modules connecting into a spine-like tower, with systems stacked in four rows around it. "The container is designed to dock with the main structure using a single mechanical port, allowing network, power, and cooling connectivity with the rest of the data center."

It is not clear how replaceable that spine is, which would presumably include its own networking gear that would also quickly age. Nor is it clear if that spine is priced into the cost calculation.

Similarly, more mundane considerations like space insurance (see our latest magazine) are not factored in.

Nonetheless, Lumen has lofty ambitions, with renders and statements about a potential 5GW deployment. That would require 4km sq of solar array, the company said.

The company declined to comment to DCD.