1. The mountain that reached orbit

Arthur C. Clarke’s The Fountains of Paradise is about building a structure so tall that it touches geostationary orbit. The desktop does not need a space elevator, but it does need to choose its altitude carefully. The wrong orbit adds drag, radiation, communication gaps, and launch cost. The right orbit makes the desktop feel like a permanent neighborhood.

Entry 188 finished the thermal budget. This entry picks an orbital home for the desktop.

2. Altitude: the 600 km band

A LEO desktop wants low latency and frequent ground access, so it stays in LEO. Within LEO, the 500–700 km band is attractive. Below 500 km, atmospheric drag is high and orbit lifetime is short. Above 700 km, radiation from the Van Allen belts increases and launch costs rise.

600 km is a practical compromise. Drag is manageable, radiation is tolerable for most electronics, and a wide range of launch vehicles can reach it. Orbit lifetime at 600 km is decades, so the desktop does not need constant reboost to stay alive.

3. Inclination: the 51.6° question

Inclination determines which ground stations and which latitudes the desktop can see. A sun-synchronous orbit near 98° is excellent for Earth observation but gives poor revisit to mid-latitudes at fixed times. An ISS-like 51.6° inclination covers most populated areas and matches many launch sites, but it does not provide global coverage.

For a general-purpose desktop, 51.6° is a reasonable starting point. It covers the majority of potential customers and launch options. If Earth observation becomes the dominant business, a second node in sun-synchronous orbit can be added later.

4. Ground access and communication windows

At 600 km and 51.6° inclination, the desktop passes over most ground stations several times per day. Continuous high-rate communication requires either a constellation of relay satellites or a network of ground stations. Without relays, the desktop will have regular gaps in coverage.

The practical answer is a mix: a few owned ground stations for command and high-value downlinks, plus commercial relay services or ground-network-as-a-service for routine data. The desktop does not need to own the whole network.

5. Debris and conjunction risk

Higher LEO altitudes have more debris and less natural decay. At 600 km, the desktop must track conjunctions and be prepared to maneuver. A small propulsion system for collision avoidance and orbit maintenance is essential.

The desktop should also be designed for controlled deorbit at end of life. A large platform that becomes debris is a liability to the entire industry.

6. The chosen orbit

Tentative choice: 600 km circular orbit at 51.6° inclination. It balances drag, radiation, launch access, ground coverage, and operational lifetime. It is not perfect for every attachment, but it is good enough for most of them.

What this changes

  • The desktop’s reference orbit is 600 km circular LEO at 51.6° inclination.
  • This altitude balances drag, radiation, launch cost, and orbit lifetime.
  • Ground access will use a mix of owned stations and commercial relay or ground-network services.
  • Debris tracking and collision avoidance propulsion are required.
  • The next leisure entry can design the communications architecture around this orbit.