Interview with Jonathan Friend from SSTL: Sending Small Sats to the Moon

moon

SSTL recently announced a project aimed at providing infrastructure for Moon missions. Exospace had the opportunity to catch up with Jonathan Friend from SSTL, in charge of the project.

– Can you quickly introduce yourself, for how long have you been working at SSTL, what were you doing before, what is your current job perimeter?

My name is Jonathan Friend and I have been a Mission Concepts Engineer at SSTL for nearly 3 years. Before joining SSTL I was a Young Graduate Trainee at the European Space Agency working on future astrophysics and fundamental physics missions. In my current role at SSTL I work on studies of future concepts for agencies, industry and internal projects, spanning topics such as Earth observation, communications, astronomy and exploration.

– Can you describe how the Lunar Communications Pathfinder Mission was born? Is this only about communications, or is there also a transportation component to the moon?

The Lunar Communications Pathfinder Mission was born out of the realisation that one of the main reasons that commercial deep space exploitation has yet to take of is because of the lack of supporting infrastructure. By providing infrastructure, the initial start-up costs for companies entering new markets such as in-situ resource utilisation will decrease. The Moon has significant potential for economic stimulation as it is a near Earth destination with abundant resources that could be utilised for sustainable space exploration. The two major hurdles that have prevented exploration of the Moon by small spacecraft are communications and a means of getting to lunar orbit.

The Lunar Pathfinder Mission aims to solve these problems by providing a means of getting to the moon and communicating back to Earth with minimal impact on customer’s spacecraft system resources. As part of the partnership, Goonhilly Earth Station (GES) is providing a dedicated ground segment using their GHY-6 32m antenna and mission operations centre. This will mean that users will only need an internet connection to command their spacecraft and receive telemetry and payload data rather than having to set up their own ground segment. The problem with just providing communications in the near term is that as yet there is no customer base of potential users other than a couple of institutional missions. By taking a collection of nanosatellites with the communications relay orbiter this problem goes away.

– From an engineering standpoint, can you briefly expose the specific challenges for deep space communications? How is it different from communications with GEO missions? (power, ground station, infrastructure, space weather…)

The system is highly dynamic, compared to GEO communications, as the spacecraft will be in a highly elliptical orbit around the Moon. In a constantly changing scene the spacecraft will need to track the Earth and the Moon simultaneously to provide the communications links and track the sun to provide power. The mission also contains more phases, with more manoeuvres and time critical events than a typical GEO comms mission, such as lunar orbit capture and nano-satellite deployment. From the ground segment point of view, tracking the spacecraft is more complicated in terms of locating the spacecraft, ranging and the spacecraft periodically passing behind the Moon.

– Some material released at 2016 iCubesat mention Mars missions as well. Are Mars communications also on your roadmap? Are the technical challenges fundamentally different than for the Moon?

In the long-term Mars communications and navigational services are an ambition of SSTL. That being said, the distances and orbital dynamics involved with a Martian mission present several challenges. The launch window for the minimum energy transfer to Mars only occurs approximately once every two years so there are added schedule risks. The transfer to Mars also takes a lot longer than the planned transfer to the Moon (7 months to Mars compared to less than one to the Moon). This longer transfer will be more challenging for a nanosatellite to survive before even starting their mission.

The greater distance from the Earth and the Sun have cascading effects on the systems requirements which necessitates larger antennas and a higher RF output power to achieve similar data rates and larger solar panels to produce the power required with a reduced amount of sunlight. This means that the system will have higher start-up costs and closing a business case may therefore rely more heavily on the uptake of the service by large institutional missions. Also, by first pursuing the lunar communications system it will be possible to leverage much of the experience and developments to mitigate risk and high initial CAPEX.

– The current Lunar Comms project is set to use UHF. What is your opinion on optical communications technologies? Could they be useful on the short term for deep space communications?

There will be a role for optical communications for lunar communication in the medium to long term but our concept will focus on RF communication for several reasons. Optical comms is particularly susceptible to the weather conditions at the ground station and therefore cannot be relied upon for mission critical operations. Optical comms would also massively increase the start-up cost of the system. It is a relatively new technology and therefore is inherently more expensive than RF comms and would require significant investment in ground infrastructure. These factors combined mean that it would be incredibly difficult to build a business case around an optical communications system for the Moon. It could be envisaged that in the medium to long term after optical comms have seen a wider commercial uptake that it could be used on lunar comms missions for large payload data dumps but it would not replace RF comms for TT&C assurance.

– What is the business model for the non-ESA commercial component of this project? Are you planning to sell communications services to other Moon missions (ex: Google Lunar X-Prize teams)? Will the system be useful for Earth-orbiting spacecrafts as well?

The idea is that, after the demonstration phase, the system will be available for any missions in cis-lunar space to purchase capacity as long as they have a compatible communications system. The level of service will initially be negotiated on a mission by mission basis. As follow-on missions are launched this aspect of the service will start to form a larger portion of the service.
There would be very little benefit in Earth orbiting satellites using the system as there are many other services which would be much easier for an Earth orbiting satellite to use.

– Do you have in mind other potential services you could propose to Lunar missions? For example, Moon gravity field is not modelled as accurately as Earth’s, which can make orbit propagation harder (just throwing ideas around).

The next step for the enhancement of the service will be for the provision of a navigation service to allow for orbit determination and surface position measurements. This will also aid communications scheduling and allow for an overall increase in data throughput. Other applications could also be enabled, such as increased autonomy of lunar mission, coordination of multiple satellite/rover, etc. SSTL has a significant amount of experience with navigation, through the involvement in producing the payload for the Galileo constellation, which can be leveraged to facilitate such a service.

– This public/private partnership, where ESA would purchase services instead of hardware, looks similar in spirit to what NASA is doing with companies such as SpaceX. Is ESA shifting its strategy on that matter, from your point of view?

In March 2015 ESA released a Call For Ideas entitled “Space Exploration As A Driver For Growth And Competitiveness: Opportunities For The Private Sector”. The aim of the call was for companies to proposed potential partnerships for exploration (to LEO, the moon and Mars). Proposers were encouraged to not only put forward a mission or technology concept but also a partnership model that they wanted to explore. In this way ESA was able to gather information on the types of services that industry where interested in providing and the way in which industry foresaw the route towards commercialisation of the services.

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