OLFAR a radio telescope based on nano satellites in moon orbit

It seems very likely that missions with nano-satellites in professional scientific or commercial applications will not be single-satellite missions. Well structured formations or less structured swarms of nano-satellites will be able to perform tasks that cannot be done in the “traditional” way. The Dutch space-born radio telescope project OLFAR, the Orbiting Low Frequency Array, is a good example of a typical “swarm task”. The OLFAR radio telescope will be composed of an antenna array based on nano-satellites orbiting the moon to shield the receiving nodes from terrestrial interference. The array will receive frequencies in a band from around 30 kHz to 30 MHz. This frequency band is scientifically very interesting, since it will be able to detect signals originating from the yet unseen “Dark Ages” ranging from the Big Bang until around 400 million year after. Another science driver is the LF activity from (exo) planets. In this paper the design parameters for the satellites and the swarm will be given and status of the OLFAR project will be reported. Details will be given about the antenna system, the LF-receiver and the signals that are expecte

On the origin of satellite swarms

For a species to develop in nature, two basically two things are needed: an enabling technology and a "niche". In spacecraft design the story is basically the same. Both a suitable technology and a niche application need to be there before a new generation of spacecraft can be developed. Last century two technologies have emerged that had and still have a huge impact on the development of technical systems: Micro-Electronics (ME) and Micro-Systems Technology (MST). Both are ruled by Moore's Law that indicates that considerable technology updates appear at the pace of years or even months instead of decades. Systems that need a development time of more than a few years will inevitably be based on "out-dated" and thereby difficult to maintain and repair technology unless during the development constant redesigns are made. This makes the development of the system at least very expensive. Although expenses do not seem to be a frequent show stopper in the design of spacecraft, it is still very interesting to investigate what system architectures might evolve when the specific properties of the new technologies ME and MST are fully exploited. ME presently offers more than 2 billion transistors on a chip and MST offers mechanical systems like resonators, mechanical switches, propulsions units, gyroscopes and many other sensors that _t in a volume of a few square millimeters to a few centimeters. So it is possible to fit a lot of signal processing power together with the necessary sensors and actuators in a volume that is really very small compared to any know space system. Of course state-of-the art spacecraft will immediately outperform these units in all aspects apart from cost and quantity. For the _rst time it makes sense to envisage the operation of formations of tens to hundreds of satellites that are cheap because they are based on standard commercial COTS technology and system designs. These satellite swarms will not be the systems that replace all other space systems. But, like in nature, there is a niche where swarms are the optimal solution. It's time to start occupying this niche. Typical properties of a swarm in nature are robustness, redundancy, large area coverage, the lack a hierarchical command structure, limited processing power per unit and self-organization ("swarm-intelligence"). This paper discusses the technological trends that lead to satellite swarms, where they can go and what new science they can create

MISAT: Designing a Series of Powerful Small Satellites Based upon Micro Systems Technology

MISAT is a research and development cluster which will create a small satellite platform based on Micro Systems Technology (MST) aiming at innovative space as well as terrestrial applications. MISAT is part of the Dutch MicroNed program which has established a microsystems infrastructure to fully exploit the MST knowledge chain involving public and industrial partners alike. The cluster covers MST-related developments for the spacecraft bus and payload, as well as the satellite architecture. Particular emphasis is given to distributed systems in space to fully exploit the potential of miniaturization for future mission concepts. Examples of current developments are wireless sensor and actuator networks with plug and play characteristics, autonomous digital Sun sensors, re-configurable radio front ends with minimum power consumption, or micro-machined electrostatic accelerometer and gradiometer system for scientific research in fundamental physics as well as geophysics. As a result of MISAT, a first nano-satellite will be launched in 2007 to demonstrate the next generation of Sun sensors, power subsystems and satellite architecture technology. Rapid access to in-orbit technology demonstration and verification will be provided by a series of small satellites. This will include a formation flying mission, which will increasingly rely on MISAT technology to improve functionality and reduce size, mass and power for advanced technology demonstration and novel scientific applications.

A novel astronomical application for formation flying small satellites

OLFAR, Orbiting Low Frequency Antennas for Radio Astronomy, will be a space mission to observe the universe frequencies below 30 MHz, as it was never done before with an orbiting telescope. Because of the ionospheric scintillations below 30 MHz and the opaqueness of the ionosphere below 15 MHz, a space mission is the only opportunity for this as yet unexplored frequency range in radio astronomy. The frequency band is scientifically very interesting for exploring the early cosmos at high hydrogen redshifts, the so-called dark-ages and the epoch of reionization, the discovery of planetary and solar bursts in other solar systems, for obtaining a tomographic view of space weather, ultra-high energy cosmic rays and for many other astronomical areas of interest. Because of the low observing frequency the aperture size of the instrument must be in the order of 100 km. This requires a distributed space mission which is proposed to be implemented using formation flying of small satellites. The individual satellites are broken down in five major subsystems: the spacecraft bus, the antenna design, the frontend, backend and data transport. One of the largest challenges is the inter-satellite communication. In this paper the concept and design considerations of OLFAR are presented

An extensive and autonomous deep space navigation system using radio pulsars

Interstellar navigation poses significant challenges in all aspects of a spacecraft. One of them is reliable, low-cost, real-time navigation, especially when there is a considerable distance between Earth and the spacecraft in question. In this paper, a complete system for navigation using pulsar radio emissions is described and analysed. The system uses a pulsar‟s emissions in the radio spectrum to create a novel system capable of fully autonomous navigation. The system is roughly divided into two parts, the front - end and the back - end, as well as their subdivisions. The front - end performs initial signal reception and pre-processing. It applies time-based coherent de-dispersion to allow for low-power on-board processing, and uses a very wide bandwidth to limit the required antenna size. As a result, the electronics required performing the processing is complex, but the system is well limited in both size and power consumption