Storage and Compute in Space

Elasticity, efficiency, and accessibility of cloud computing has resulted in the wide-spread use of data centers. Public cloud offerings (e.g., AWS, GCP, Azure) provide eleven nines of durability, impressive regulatory compliance (HIPAA, GLBA, ITAR) and significant reductions in capital expenditures. Public clouds protect against data loss by using redundant data centers located at diverse locations on Earth. This idea of creating a cloud of servers is so good that soon every individual in the developed world will have one ‘interaction’ with a data center every 18 seconds over their life span [1].

Limitations of Terrestrial Data Centers

Earth-based data centers, however, are not invincible to the risk of extreme weather events. Although highly unlikely, a natural or man-made global calamity on Earth could risk wiping out our digital footprint, if not preserved. The Arctic World Archive is an Earth-based initiative to preserve the memory of our world [2]. Alternatives that liberate our history and data from the planet would be ideal.

Data centers are also huge consumers of the resources of our planet. Some forecasts project the energy demands of datacenters to constitute about 8% of the projected global energy demand by 2030 [3]. These projections are overly pessimistic as innovations in technology such as hyper-scaling and better scheduling with AI [4] will improve the power usage effectiveness (PUE) resulting in lower energy wastage. Despite innovation in technology, terrestrial data centers consume terrestrial resources (mainly energy and trillions of gallons of water for cooling). Therefore, self-sustaining alternatives that do not require recurring resources from our planet would be worth pursuing.

The Space Industry

The launch-cost to low-earth orbit has decreased drastically, approximately from \$50,000 to \$3000 per kg. Lower barrier to entry has renewed commercial interest in space with many space-related startups being founded in the recent years. As a result of this new-space era’s activity, space is estimated to grow to a trillion dollar industry by 2040 [5]. Nearly half of the size of the industry is contributed by the satellite technology whereas the other half is mainly space exploration. Many LEO mega-constellations with the hopes to provide global internet services that are on par with terrestrial networks such as 5G are planned. These include Starlink (12,000 satellites), OneWeb (~700 satellites ) and Kuiper (~ 3000 satellites) among others. Currently, the satellites in these mega-constellations act merely as relay devices.

Space-based Data Centers

While currently all data from space is transmitted to terrestrial data centers, there is a possibility to reverse this direction: sending data from the Earth to space for storage and processing.

Storage of data in space has several advantages including protection of the data against natural or man-made disasters on Earth, liberation from data residency regulations, and mitigation of some types of cyber attacks such as wiretapping, among others.

One envisioned architecture for space-based data centers is to use low-earth orbiting satellites as the storage servers. Thus, the whole constellation could act as a distributed server farm. A limited number of ground stations could act as the gateway layer mediating access between the LEO-based storage layer and the customer layer.

Space-based data center where low earth orbiting satellites serves as storage nodes. Figure reproduced from Huang et al. [6].

The resources on-board a LEO satellite are rather limited for compute workloads. In order to enable compute workloads, it may be possible to host compute infrastructure on-board space habitats. While there are only 13 humans in space as of this writing, more governmental, tourism and commercial activity is expected in the near future creating more space habitats farther and deeper in space. Data centers aboard these habitats could host self-sustaining compute infrastructure perhaps using asteroidal water for cooling and using LEO constellations for low-latency communication to augment the terrestrial data centers.

Challenges of Space Data Centers

There are several challenges creating viable data centers in space. A few key challenges storing data in space are listed here.

  1. Enabling technology: Manufacturing of robust electronics that can withstand the space environment is very costly. The atmospheric drag on LEO satellites results in a considerably shorter lifetime compared to servers in a terrestrial data centers.
  2. The nodes in a LEO based space data centers are visible to a ground station for only a few minutes at a time resulting in a challenging scheduling problem
  3. Spectrum and power resources in the system are very limited and require sophisticated algorithms to utilize efficiently
  4. The space environment is harsh, littered with debris. In order to achieve robustness replication or network coding is required both of which are either costly or introduce latency.

Despite the enormous challenges, the idea of space data centers is exciting. There are already commercial efforts to create space based data centers such as Cloud Constellation’s Space Belt [7]. If we aspire to be a multi-planetary species, it might help to take our data along with us!

[1] Data center power consumption: Danfoss
[2] Arctic World Archive
[3] How to stop data centers from gobbling up the world’s electricity, Nature 2018
[4] Safety-first AI for autonomous data center cooling and industrial control
[5] Investing in space: Morgan Stanley
[6] Envisioned wireless big data storage for low-earth-orbit satellite-based

[7] SpaceBelt

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