# Computing in orbit

Power, heat, communications, deployment and lifetime have to work together.

Type: Research + examples · Reviewed: 4 October 2026

## Space is not free cooling

NASA’s thermal guidance explains that vacuum removes convection: heat moves through internal conduction and exchanges with the external environment through radiation. Electronics still need a thermal path to a surface capable of rejecting heat.

Radiator area, temperature, emissivity, orientation and incoming solar or planetary radiation affect the balance. A mission must manage both useful heat rejection and unwanted heating.

Source: [Small spacecraft: thermal control](https://www.nasa.gov/smallsat-institute/sst-soa/thermal-control/) — NASA. Heat transfer in vacuum and spacecraft thermal management.

## A first-order radiator calculation

Our idealized calculation assumes emissivity 0.9, a 300 K radiator and negligible incoming heat. Using σ ≈ 5.67 × 10⁻⁸ W·m⁻²·K⁻⁴ gives roughly 413 W per square metre. Rejecting 1 MW needs about 2,420 m² of effective emitting area.

Effective emitting area is not necessarily panel footprint: geometry may allow both sides to contribute. Real design includes view factors, thermal gradients, environmental heat and margin.

```text
Q ≈ ε × σ × A × (T_radiator⁴ − T_environment⁴)
```

Source: [Small spacecraft: thermal control](https://www.nasa.gov/smallsat-institute/sst-soa/thermal-control/) — NASA. Heat transfer in vacuum and spacecraft thermal management.

## Match work to communications

A job importing large datasets from Earth has a different burden from a job processing data already in orbit. Sustained transfer, contact interruptions and result size matter alongside peak link speed.

Turyshev’s April 2026 preprint models power, thermal rejection, communications, utilization and mission lifetime together. It identifies space-native preprocessing and relay-integrated edge work as plausible early regimes. Its conclusions depend on the model assumptions.

Source: [Orbital Data Centers: Spacecraft Constraints and Economic Viability](https://arxiv.org/abs/2604.27197) — Slava G. Turyshev · April 2026 preprint. Model-dependent analysis of power, mass, communications, utilization and lifetime. A preprint, not demonstrated operation.

## Evaluate the lifecycle

The ASCEND consortium’s 2024 study summary says substantial emissions improvements would require a launcher with ten times lower lifecycle emissions in its study context. Avoiding water-based cooling does not settle manufacturing, deployment and replacement impacts.

ESA’s 2026 environment report reinforces the importance of orbital sustainability. A credible infrastructure proposal includes collision avoidance and end-of-life disposal along with its payload budget.

Source: [ASCEND feasibility study results](https://www.thalesaleniaspace.com/en/press-releases/thales-alenia-space-reveals-results-ascend-feasibility-study-space-data-centers-0) — Thales Alenia Space · 2024. A consortium summary of orbital data-centre feasibility and lifecycle conditions.

Source: [Space Environment Report 2026](https://www.esa.int/Space_Safety/Space_Debris/ESA_Space_Environment_Report_2026) — ESA · September 2026. Orbital sustainability, reentry and disposal trends.

## Study the workload before the scale

| Workload | Why investigate it | Main constraint |
| --- | --- | --- |
| Observation preprocessing | Inputs originate in space | Onboard power and reliability. |
| Relay-integrated processing | Work occurs within a communications system | Link availability and integration. |
| Earth-facing batch compute | Timing may be flexible | Transfer and delivered cost. |
| Distributed training | A long-term capacity concept | Interconnect, replacement and utilization. |

> Research synthesis: this comparison identifies questions to test, not deployed SpaceXSI services.