Variable-geometry solar sailing: the possibilities of the quasi-rhombic pyramid

Variable geometry solar sailing potentially offers enhanced delta-V capabilities and new orbital solutions. We propose a device with such capabilities, based upon an adjustable quasi-rhombic pyramid sail geometry, and examine the benefits that can be derived from this additional flexibility. The enabling technology for this concept is the bevel crux drive, which can maintain tension in the solar sail across a wide range of apex angles. This paper explores the concept of such a device, discussing both the capabilities of the architecture and the possibilities opened up in terms of orbital and attitude dynamics

Synchronized orbits and oscillations for free altitude control

No abstract available

Development and enhancement of various mechanical oscillators for application in vibrational energy harvesting

The context of this thesis surrounds the development and study of the effectiveness of three mechanical-to-electrical energy converter concepts that are based upon oscillatory systems with a view of discovering techniques to enhance their normal functioning throughputs. The field of energy harvesting has experienced significant growth over recent years with the increased popularity of portable electronic devices and wireless sensors. However, with demand, so too rises the need for increased operating lifetimes not only for extended use for some personal devices, but also to reduce the frequency of periodic battery replacements for remote sensors that may be deployed in potentially hazardous environments. In light of this need, the proceeding chapters will discuss the development of three conceptual energy harvesters. The first is based upon a simple Euler strut that is intended to harvest known steady-state periodic vibrations applied axially to the beam. The assumption here is that the periodic vibrations would arise from ambient conditions, whether naturally occurring or as a form of waste energy from man-made structures. This concept has built into it the facility to apply a static axial pre-load with which, it will be shown, can be used to passively enhance the energy throughput of the device. However, it will also be shown that the periodic concept has an inherent sensitivity to excitation frequencies, where even minor shifts can result in significantly reduce outputs. To this end, the second harvester was proposed to relieve this limitation by instead harvesting stochastic inputs. With this in mind, the new concept is again based upon a simple and realisable Euler strut but with the stochastic input applied laterally to the supporting structure. By retaining the facility to apply both static and dynamic axial loads, it will be shown that the cumulative effects of the deterministic and stochastic input can be manipulated to actively enhance the throughput of this system also. However, given the active nature of this form of control that will consume work during its implementation, an approach for ensuring that the net energy will be reduced by this additional work will be discussed. In this way, a conservative estimate of the harvestable energy may be made. The final energy harvester to be discussed is based upon a planar pendulum that can integrate mechanical accelerations out of the full three degrees of freedom realisable by planar constructs. This begins with the development of a suitable approach to applying rotational excitations to the device, followed by the development of a set of loading terms used to represent the resistive torque that would be exerted upon the system by a suitable power take-off device. This is followed by a comprehensive parameter study of the proposed concept with a mindset towards optimising the operational performance of the device

From miniature satellites to giant sun shields – the extreme technology transforming space engineering

Scientists are hoping to turn tiny spacecraft into starships by coupling them with large solar sails

Emerging space technologies: macro-scale on-orbit manufacturing

Advanced additive manufacturing (AM) technologies have the potential to change the way in which satellites and spacecraft are deployed in orbit by removing traditional launch constraints, whether faring volume or launch loads, and allowing space structures to become larger, lighter and more capable with integrated features. These same approaches may also be exploited for on-orbit servicing, thereby potentially extending the operable lifetime of space infrastructure and increasing cost effectiveness. This paper will provide an overview of the key issues associated with on-orbit manufacturing and discuss the use of AM technologies and investigate the next wave of emerging space technologies enabled by on-orbit manufacturing

Emerging Space Technologies: Macro-scale On-orbit Manufacturing

Advanced additive manufacturing (AM) technologies have the potential to change the way in which satellites and spacecraft are deployed in orbit by removing traditional launch constraints, whether faring volume or launch loads, and allowing space structures to become larger, lighter and more capable with integrated features. These same approaches may also be exploited for on-orbit servicing, thereby potentially extending the operable lifetime of space infrastructure and increasing cost effectiveness. This paper will provide an overview of the key issues associated with on-orbit manufacturing and discuss the use of AM technologies and investigate the next wave of emerging space technologies enabled by on-orbit manufacturing

Laboratory-Scale Test Platforms for Femto-Satellite Attitude Control Systems

Femto-satellites have attracted growing attention over the past few years, with various universities taking up the challenge declared by the N-Prize. Many novel designs have been proposed, some of which are equipped with active attitude control based on either magnetic or electro-chromic control systems. However, conventional test platforms are unsuitable for testing control systems on such small length-scales and as such, developing suitable test platforms to be used for testing femto-satellite attitude control algorithms becomes important. This paper proposes six different concepts of laboratory-scale test platforms for femto-satellite attitude control testing, based on various physical laws. These platforms are manufactured using SLA 3D printing technology and then assembled. Qualitative observations are recorded and an experimental setup is devised in order to quantify the total resistive torque that appears in each platform. Results show that two of the designs display a maximum resistive torque on the order of 10^(-6) when spinning very rapidly, decreasing to the order of 10^(-7) at low angular velocities, which makes these designs suitable for their intended purpose. Finally, future work is proposed towards assessing the suitability of the other four platforms

Development status of AEOLDOS - a deorbit module for small satellites

A prototype CubeSat module to deploy a gossamer aerobrake, using strain stored in tape-springs, at end-of-life is described. A novel hub geometry to reduce bending shock at end-of-deployment while simultaneously permitting radial, as opposed to tangential, deployment is proposed. The rpm of the hub is measured under various deployment conditions to verify that the system offers highly-repeatable performance, while high-speed photography is used to characterise the behaviour of the tape-spring during unspooling and contrast it to the behaviour of a traditional tangential-deployment system. Secondly the folding pattern of the membrane, which takes advantage of the symmetrical deployment offered by the petal hub, is developed and the unfolding mechanism is verified by numerical and experimental analysis. Finally, the release of the stored strain is considered and a novel burn-though device is designed and prototyped to meet this requirement

Lessons learned from REXUS12'S Suaineadh Experiment : Spinning deployment of a space web in milli gravity

On the 19th of March 2012, the Suaineadh experiment was launched onboard the sounding rocket REXUS 12 (Rocket Experiments for University Students) from the Swedish launch base ESRANGE in Kiruna. The Suaineadh experiment served as a technology demonstrator for a space web deployed by a spinning assembly. Following launch, the experiment was ejected from the ejection barrel located within the nosecone of the rocket. Centrifugal forces acting upon the space web spinning assembly were used to stabilise the experiment’s platform. A specifically designed spinning reaction wheel, with an active control method, was used. Once the experiment’s motion was controlled, a 2 m by 2 m space web is released. Four daughter sections situated in the corners of the square web served as masses to stabilise the web due to the centrifugal forces acting on them. The four daughter sections contained inertial measurement units (IMUs). After the launch of REXUS12, the recovery helicopter was unable to locate the ejected experiment, but 22 pictures were received over the wireless connection between the experiment and the rocket. The last received picture was taken at the commencement of web deployment. Inspection of these pictures allowed the assumption that the experiment was fully functional after ejection, but probably through tumbling of either the experiment or the rocket, the wireless connection was interrupted. A recovery mission in the middle of August was only able to find the REXUS12 motor and the payload impact location