The story of spaceflight is rapidly evolving. Early chapters rightfully focused on the journey to space – the launch. While the ride to orbit remains the most visible portion of spaceflight, a revolution is happening in orbit as larger launch vehicles and smaller, more capable satellites expand access to space. This accessibility, coupled with the burgeoning capabilities of the space infrastructure industry, is rewriting what’s possible in orbit – and beyond.

In-space infrastructure will supply the critical platforms, services and capabilities that can help optimize the use of space. In the early days of spaceflight, mission designers were true pioneers. Infrastructure – launch complexes, communications networks, etc. – was limited to what had been built on the ground. While there has been some migration of support infrastructure to space, this migration is still in its infancy and most space missions are fully self-reliant once in space.

As space activity expands, we are approaching a critical mass of activity where providing common functions as a service becomes practical and cost-effective. Two areas where this tipping point is being met are in-space transportation and data transport.

Space Transportation

The increasing number and growing capabilities of small satellites, combined with the inherent economies of scale of large launch vehicles, have created a rideshare launch economy. Many small satellites are aggregated onto and share the cost of an efficient large rocket launch to get to space. This is analogous to large container ships crossing oceans or rail transport of goods on land. But once in space, the satellite cargo may need to be distributed further – to various mission-optimal orbits. Since the rocket can only drop off in one place, the need for an in-space transportation system is emerging. This challenge is being met by a combination of in-space transport tugs and a large number of emerging small satellite propulsion technologies that allow small satellites to move themselves to their optimal orbit destination. This last-mile delivery service is a foundational enabler for various missions, including Earth observation, communications, Internet of Things (IoT), and missions performed by the Department of Defense, like space situational awareness.

Data Transport

Data transport is the second near-term challenge. Part of the increase in satellite activity is being driven by constellations of Earth Observation satellites. Miniaturization of sensors and electronics, combined with advances in artificial intelligence, has created a market for near real-time Earth Observation data products. This has resulted in a huge increase in the amount of space data being gathered and a demand that this data be downlinked to the ground quickly to serve low-latency data consumers.

This poses several challenges to the constellation operator. One is that downlinking data requires a license for RF spectrum to be obtained – and more data means the operator needs more frequencies assigned to them. And RF spectrum is a very limited resource.

The second problem is that the satellite can only downlink data when over a ground station. LEO satellites don’t see much of the Earth at once, so a constellation of LEO satellites needs a global network of ground sites.

A traditional approach where each mission builds out its own global ground network and requires allocation of enough RF spectrum to cover its peak needs is expensive. As this approach is scaled – with many parallel and independent systems, it’s clear that a centralized infrastructure solution is more efficient.

System elements, which must be sized for coverage (vs. utilization), can then be driven at higher utilization by sharing the resource over multiple different users, each paying a fraction of the total system cost.

While addressing these tipping points, the industry also has the opportunity and responsibility to do so sustainably.

Space missions tend to be very expensive. But that’s not unique to infrastructure projects.

Most terrestrial infrastructure projects are also big, complicated, and expensive. For example, the new San Francisco-Oakland Bay Bridge cost about $6B. The James Webb Space Telescope cost about $10B. A bit more, but certainly on the same scale.

The big difference is that the Bay Bridge is expected to be maintained to have an operational lifetime of 100 years or more. The James Webb Telescope, which took 30 years to design and build, is designed for an operational life of only 5.5 years. Engineers hope that it may last as long as 10. This is an extreme example, but commercial GEO Spacecraft cost hundreds of millions to billions of dollars to produce and last perhaps 15-20 years, after which they must be replaced to provide continuity of service. Space operates as a disposable economy – but with the capital costs consistent with large infrastructure projects.

The approach we are taking to space today is not sustainable. However, the increase in space activity that’s creating opportunities for in-space transportation and data transport also creates an opportunity for a sustainable approach to space.

With large numbers of space vehicles in close relative proximity, business cases for satellite servicing and orbital removal begin to close. With further evolution of technologies, in-space manufacturing, servicing, and recycling are likely to follow. These capabilities will allow space infrastructure to become maintainable – extending the useful life of systems to 50 years or longer, approaching the lifecycle of terrestrial infrastructure. In turn, lifecycle costs will decrease, and space-based businesses will grow.

Maintenance, manufacturing, and debris removal all require transport logistics. This will further leverage the capabilities of in-space transport systems. But it also creates a need for in-space refueling. It’s not practical for a transportation system to carry a lifetime of fuel with it from the start (though that’s how space missions operate today).

Initially, refueling supplies will likely be launched to orbit and the in-space transport vehicle will rendezvous with the launch system to transfer fuel to itself. As activity increases, propellant delivery services will emerge, and eventually a network of fuel depots will emerge as the most efficient means of supporting in-space transportation logistics.

As the overall support infrastructure in space develops, particularly in-space manufacturing, recycling, and maintenance, dependence on the Earth for space activities will decrease, allowing for more economical activities far from Earth. Sourcing of more local raw materials for manufacturing will emerge, along with technologies that are supported by available off-Earth resources.

This extends to propulsion systems as well. Water will likely emerge as a primary off-Earth propellant source due to its relative abundance throughout the solar system. Propulsion approaches that leverage off-Earth propellants will be needed to avoid the logistical costs associated with Earth-sourced fuel. This is a key reason why Momentus uses water as the propellant for our Microwave Electrothermal Thruster (MET) to propel our orbital service vehicle (OSV). We plan to use the MET and our OSV in Low Earth Orbit initially and then extend its range and capabilities to support missions on and around the moon and beyond.

Space infrastructure companies, like Momentus, aim to provide services to advance how humanity uses and explores space. Like the early railroads, highways, and commercial air travel connected people and ideas, and enabled movement and growth, space infrastructure will enable the same. As the story of spaceflight continues, space infrastructure is sure to make the next chapters some of the most exciting and impactful.

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