Small Satellite Market Growth
The phenomenal advances in electronics have enabled the current generation of small satellites to perform missions which previously required much larger satellites. The cascading savings that result from a smaller payloads promises satellite missions that only cost a fraction of what was previously possible. In fact, widespread use of small satellites could completely change the economics of space.
For example, consider a small low-cost satellite. Since the initial capital cost is low, the satellite can be replaced every few years. The owner is therefore not locked into a specific technology for the customary 10-20 year period. But moreover, the satellite need only be designed for a lifetime of only 3-4 years, significantly reducing the cost and complexity of the satellite. Similarly, only a modest propellant load needs to be carried, further reducing mass and cost. Due to the short lifespan, the small satellite can be placed in a very low orbit which further reduces mass (e.g. smaller optics for a given resolution requirement) and therefore also cost. And of course all satellite mass reductions should also translate in significant savings in the launch cost.
It should be clear that any initial reductions in the mass and cost of a satellite are quickly multiplied to deliver mission costs that can be an order of magnitude cheaper than traditional missions.
Space Debris Considerations
Arguably even more important than mission cost is the mitigation of space debris. The volume of space debris in the most useful low earth orbits is becoming a significant risk to spacecraft operators. And projections show that the risk will significantly increase in future.
Low cost access to space could unfortunately cause a further exponential increase in space debris. Proliferation of small, low-cost satellites that only have a useful life of months or years (in some cases weeks) will massively increase the volume of debris. Since these satellites are currently launched on shared manifest launches with larger satellites, the resulting increase in debris will be concentrated in the most useful Sun-Synchronous Orbits. And the decay time of these orbits is measured in decades.
Clearly, action is needed to protect the valuable Sun-Synchronous Orbits from these risks, while not harming growth in the small satellite market. There is only one practical alternative to achieve this, namely to launch small satellites into very low orbits that decay naturally within short periods of time. Not only is this desired by most small satellite manufacturers (as mentioned above), it will also ensure that any space debris will re-enter the atmosphere and burn up within a matter of years, if not months. As such, these very low orbits (up to about 400km) can be considered a renewable resource that is self-cleaning and can be sustainably used on a much larger scale than any other orbit type. In fact, sub-400 km orbits may well be the only way that near-earth space can be sustainably used.
The Need for Small Launchers
Currently, no low-cost small satellite launchers exist. As previously mentioned, small satellites therefore have to be launched either as piggyback payloads on shared manifests. This situation does not remain viable on the long term due to the following risks:
- No control of orbit: Inability to reach to very low orbits on shared launches with larger satellites that are launched to much higher orbits. This prevents small satellites achieving their true potential of high resolution imagery at low cost while significantly adding to the space debris problem (as described above)
- No control of launch reliability: Concerns about the availability of small Russian launchers due to the age of the converted missile fleet and political uncertainty
- No control of launch schedule: Significant delays of up to two years is not uncommon (after already waiting some years for a suitable launch opportunity)
- Intellectual Property and Security Concerns: Satellites leaving the UK and EU may be subject to inspection by other nations and companies, jeopardising commercial and national confidentiality
Therefore, there is a clear need for a fleet of launch vehicles that are dedicated to the launch of small satellites into very low orbits. Several potential systems are currently in development, but these are either fully expendable or fully reusable. Both of these extremes have historically been proven not to be cost optimal. This can be seen, for example, from the very high cost (per kilogram) of the Vega expendable launcher, as well as the very high cost of operational space planes (most notably the Space Shuttle).
Research performed by Heliaq has shown that the flyback booster concept is however cost optimal. As such, the Austral Launch Vehicle (ALV) project has been created to develop flyback boosters specifically for small satellites.