Visionary Space Systems: Orbital Dynamics at Extremes of Spacecraft Length-Scale (Visionspace)

One of the world’s leading authorities on the subject of solar sails, Professor Colin McInnes talks to EU Research about the VISIONSPACE project and the development of novel approaches to orbital dynamics to improve telecommunications and space exploration

VISIONSPACE: Taking Orbital Dynamics to New Levels Since the launch of Sputnik, the first manmade satellite in 1957, the number of satellites in orbit around Earth has increased dramatically. Current figures from the Space Surveillance Network estimate that there are around 8000 objects in orbit around the planet with a diameter no smaller than 10cm; of this number, 974 are operational satellites, with the rest being made up of dead satellites and assorted space debris. As the relative costs of production have decreased and demand has increased over the years, governments, space agencies, and companies have found themselves in a position to place more satellites in orbit with relative ease. As a direct result of this, orbital space around the planet in the most useful orbits is becoming something of a premium; the space in space, as it were, is running out around Earth.

This is just one of many challenges being addressed by the VISIONSPACE project, a

five year project funded by a European Research Council Advanced Investigator Grant. Based at the University of Strathclyde’s Advanced Space Concepts Laboratory (ASCL), which opened in 2009 under VISIONSPACE funding, the project is investigating a number of avenues of orbital dynamics that have far reaching applications for use in space exploration, the enhancement of telecommunications capacity, as well as developing novel spacecraft designs with both commercial and scientific applications.

Professor Colin McInnes is the VISIONSPACE project’s Principle Investigator, and Director of the ASCL. His work on solar sails has made him one of the leading figures in the field, and his current research interests centre on the orbital dynamics and mission applications of solar sail

spacecraft. Part of this work includes the development of families of highly nonKeplerian orbits for solar sails and other spacecraft which can enable novel applications.

Professor McInnes spoke to EU Research about the VISONSPACE

Swarm of ‘smart dust’ sensor nodes

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project and some of the avenues they have been investigating.

One of the primary goals of the VISIONSPACE project is to investigate ways of establishing novel orbits that would provide new opportunities for space science, telecommunications and Earth observation.

For example, VISIONSPACE has been instrumental in proving a theory that, until recently, had been thought impossible. The use of a levitated geostationary orbit, accomplishable with the aid of a solar sail, would allow satellites to follow an orbital path that sits outside normal, Keplerian orbits.

Professor McInnes and PhD student Shahid Baig have published a paper showing that the use of a solar sail attached to a satellite could elevate its orbit between 10 and 30 km north or south of the standard.

“Attaching a large reflective sail could utilise sunlight to propel a satellite above or below the equator,” Professor McInnes explains. “This would provide enough thrust to sustain a geostationary position, almost indefinitely, without the need for any additional fuel that would otherwise be required to maintain this orbital position.”

These non-Keplerian orbits present an opportunity to significantly boost the number of satellites that can be placed in orbit around the Earth in popular orbits, offering applications for greater telecommunications networks, as well as for weather forecasting among others.

Another aspect of the VISIONSPACE project, also incorporating novel orbits, is the investigation into stationary orbits with a particular focus on the two poles. These

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Solar sail trajectory - ‘pole-sitter’ orbit for polar Earth observation ‘Pole Sitters’ are devices that would utilise solar sail propulsion and solar electric propulsion in hybrid form in order to sustain a continuous stationary position above the poles. Professor McInnes explains: “This would mean that we can capture real-time observations of the Earth’s poles, with a full hemispheric view, and could enable a wide range of new applications, including monitoring of the ice cover and line-of-sight telecommunications to high-latitude regions.” System designs have been drawn up, and the hybrid solar sail propulsion / solar electric propulsion has the potential to offer significant improvements to mission performance.

Earth-centred orbits are not the only concern of the VISIONSPACE project; there are other aspects of the project which offer

many possibilities. Near Earth Asteroids are one of the biggest long-term threats to our planet from space; the devastation caused if one were to collide with us could potentially wipe out life as we know it. However, they also represent a valuable source of materials for future large-scale space engineering ventures.

As Professor McInnes explains: “You would be surprised how easy it is in principle to manipulate the trajectory of an asteroid; using a continuous push from a spacecraft and altering the trajectory of the asteroid at just the right point, it would be possible to manoeuvre one into orbit around Earth.”

Such a venture would provide us with a wealth of raw materials that can be used to prime future ventures in space exploration and exploitation. “A 24 meter M class asteroid could potentially provide around 30,000 tonnes of metal, and even 1 tonne of Platinum Group Metals.” This would save the need to transport such materials into space, saving launch costs in the process.

Other benefits could be harvesting the water content of such asteroids; there are many objects that are hydrated carbonaceous asteroids, and as such could produce significant volumes of water.

Further research within the VISIONSPACE project is investigating the possibility of a solution to global climate change in space.

The concept of geo-engineering looks at altering the planet’s climate by using large clouds of small dust grains to help reduce the amount of sunlight that reaches the Earth. In statistical terms, a 1.7% reduction of sunlight reaching the planet will offset

EU Research

At a glance Full Project Title Visionary Space Systems: Orbital Dynamics at Extremes of Spacecraft Length-Scale (Visionspace)

the effects caused by a 2 degree increase in global temperature. “The process is called solar insolation reduction,” Professor McInnes explains. “It can be achieved by dispersing dust particles from NEAs, or even transporting dust from the surface of the Moon using mass drivers.” The dust clouds could be placed close to the first Lagrange point between the Sun and the Earth, where it would be relatively unaffected by gravity and would loiter on the Sun-Earth line. Another aspect of this particular investigation is to investigate the possibility of using a captured NEA positioned at the Lagrange point in order to form an “anchor” for the dust cloud, therefore increasing its effectiveness.

Professor McInnes spoke about the future possibilities of swarm technology within space based applications. “Recent advances in miniaturisation have enabled the fabrication of spacecraft with smaller length scales,” he explains. “There are even examples of spacecraft with the dimensions of a single microchip.” Such spacecraft are relatively low cost in terms of their manufacture, and so vast numbers of these “smart dust” devices can be constructed for use in a number of swarm applications, such as global sensor networks for Earth observation and communications, real-time sensing for space science, and to support damage detection with conventional space craft among others. VISIONSPACE’s considerations of orbital dynamics will come into play with this research as many of the swarm applications will rely on solar radiation pressure and aerodynamic drag to manoeuvre the smart dust devices into orbits around the Earth. “On top of this, the short life-time of the swarm can be increased by utilising the same light pressure to gain energy, and the drag to dissipate it.”

Furthermore, the effect of drag can be

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exploited at mission’s end in order to ensure that no long term debris is left in orbit; the idea is that the swarm burns up in it’s entirety within the Earth’s atmosphere.

Professor McInnes describes the VISIONSPACE project as blue-skies research.

Some aspects of the research being undertaken as part of the project are not applicable as yet in the real-world due to technological limitations; however, the results of the project will provide us with a clearer picture of the plausibility of such ventures, “the key benefit of European Research Council support is the ability to conduct curiosity driven research which can help shape the future.”

The benefits from the VISIONSPACE project are not limited to the scientific communities and governments; the knock on effect of the research being undertaken by the project has the potential to bolster the local economy.

Professor McInnes commented that: “the space sector looks as if it could be immune from the effects of the recession”. He highlighted rapid growth within the UK and European space sector, and believes that: “there is a successful collaboration between companies and academics to help bring jobs to Scotland in this growing sector.”

In recognition of the work that the project has already done, the ASCL was awarded the 2011 Sir Arthur C Clarke Award for Achievement in Space Research, held at the UK Space Conference at Warwick University; Professor McInnes remarked that: “this was recognition of the space innovation delivered by the entire team at the University of Strathclyde.”

Project Objectives VISIONSPACE will deliver radically new approaches to orbital dynamics at extremes of spacecraft length-scale to underpin new space-derived products and services.

Project Funding Total VISIONSPACE proect budget is €2.1million (2009-2014) Project Partners The Advanced Space Concepts Laboratory works with a broad range of academic, industry and agency partners including EADS Astrium, Clyde Space and the European Space Agency.

Contact Details Project Coordinator, Colin McInnes Department of Mechanical and Aerospace Engineering University of Strathclyde T: +44 0141 548 2049 E: colin.mcinnes@strath.ac.uk W: www.strath.ac.uk/space

Colin McInnes

Project Coordinator

Colin McInnes is Director of the Advanced Space Concepts Laboratory at the University of Strathclyde. His work includes the investigation of families of novel spacecraft orbits and their mission applications, autonomous control of multiple spacecraft systems and advanced space concepts. Recent work explores new approaches to spacecraft orbital dynamics at extremes of spacecraft length-scale to underpin future spacederived products and services. McInnes has received national and international awards including a Philip Leverhulme Prize, the Royal Aeronautical Society Pardoe Space Award, and the Ackroyd Stuart Propulsion Prize. The International Association of Space Explorers awarded him a Leonov medal in 2007.

Space-based approaches to terrestrial geo-engineering

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