Balloon to Orbit: A Midway Station Idea | rune.ᚾ

The Problem

Getting to orbit is expensive. Most of the cost comes from fighting through atmosphere:

Ground launch challenges:
├── 100% atmospheric density at sea level
├── Most fuel burned in first 10km (fighting drag)
├── Engines optimized for sea-level pressure
└── Current cost: ~$2,720/kg to LEO (Falcon 9)

The Inspiration

Two things that already work:

High-altitude balloons - Red Bull Stratos (2012) reached 39km. Felix Baumgartner jumped from near-space. Google’s Project Loon floated at 20km for months. NASA runs regular stratospheric balloon missions.

Rockoons - The concept of balloon-launched rockets dates to 1949. James Van Allen used them to discover the Van Allen radiation belts. The idea works - it just hasn’t been scaled.

What if we combined them with a permanent platform?

The Physics

At 40km altitude, conditions change dramatically:

Atmospheric comparison:
├── Sea level:  101.3 kPa, 1.225 kg/m³
├── 18km:       ~7.5 kPa, ~0.12 kg/m³ (1/10th)
├── 35km:       ~0.6 kPa, ~0.008 kg/m³ (1/150th)
└── 40km:       ~0.3 kPa, ~0.004 kg/m³ (1/300th)

This matters for two reasons:

1. Engine efficiency increases dramatically

Rocket thrust depends on the pressure difference between combustion chamber and ambient air. The Rocketdyne Atlas MA-5 demonstrates this:

Sea-level Isp: 253 seconds
Vacuum Isp: 309 seconds
22% performance increase just from altitude

2. Drag losses nearly vanish

Drag scales with atmospheric density. At 40km, you’re operating in effectively vacuum conditions. A 2016 Acta Astronautica study concluded that “low-mass and high altitude launches give the best results.”

The Idea

What if instead of single-use balloon launches, we built a permanent floating platform?

Concept:

100km+ ─── Orbit (target)
  ↑
  │ [Small rocket - 90% less fuel needed]
  │
40km ──── Permanent platform
  ↑       ├── Rigid airship (helium)
  │       ├── Solar powered
  │       ├── Docking ports
  │       └── Staging area
  │
  │ [Balloon ascent - cheap, reusable]
  │
0km ───── Ground

The key innovation: reusability at the staging layer.

Current rockoon concepts use disposable balloons. A permanent platform changes the economics entirely - you amortize the infrastructure cost across many launches.

Napkin Math

Caveat: these are rough estimates, not engineering specs.

Delta-V savings:

NASA research on high-altitude launch suggests:

15km launch altitude → ~60% payload improvement for SSTO
40km would be significantly better (near-vacuum conditions)

Cost comparison (speculative):

Traditional ground launch:
  $2,720/kg × 100kg = $272,000

Balloon lift + small rocket from 40km:
  Balloon operations: ~$50/kg (based on HAB costs)
  Smaller rocket: ~$500/kg (if 90% fuel reduction)
  Platform amortization: ~$100/kg (spread across many launches)
  Total: ~$650/kg (speculative)

The arXiv paper on steam balloons (Janhunen et al.) showed a 10-tonne rocket could reach 18km with only 1.4x the rocket mass in steam. Lighter payloads could go higher.

What Already Exists

This isn’t science fiction - components are proven:

Leo Aerospace (now acquired) was developing rockoon tech
Zero 2 Infinity (Spain) has shifted to balloon-launched satellites
Purdue University successfully launched a rocket from high-altitude balloon in 2019
Stratoflight is building balloon spacecraft for 35km altitude

The missing piece is the permanent platform concept.

Open Questions

Things I don’t know:

Station-keeping at 40km - Can a rigid airship maintain position long-term? The stratospheric Goldilocks zone research suggests altitude control is possible but complex.
Docking in thin atmosphere - How do you reliably dock a balloon with a platform at 40km?
Rocket ignition at altitude - Thermal management and ignition systems need to work in near-vacuum, extreme cold.
Economics at scale - Does the platform cost justify itself vs. disposable rockoons?

Why Post This

I’m not an aerospace engineer. This is just an idea that seems interesting.

If someone with actual expertise thinks it’s stupid, I’d love to know why. If someone wants to build it, go ahead. Ideas should be free.

The best outcome is someone reading this and either:

Explaining why it won’t work (I learn something)
Building it (everyone benefits)

Rune QQ ᚾ nauthiz - what you need January 29, 2026