Number 19: 24/03/2002
A scientific publication by SGF and NEODyS

Special: the results of ESA's call for proposal

Mission: "SIMONE"

Description of the study :

SIMONE is a mission concept comprising a fleet of low-cost microsatellites that will rendezvous with different NEOs , each of a distinct spectral and/or physical type. In-situ science measurements taken by instruments on-board each spacecraft enable the wide diversity in the physical and compositional properties of the NEO population to be characterised in a highly cost-effective manner.
The in-situ measurement data will provide the critical physical/compositional information needed for the accurate prediction of impact risk (particularly damage potential) posed by NEOs and for the development of effective NEO risk mitigation strategies that are specifically tailored for each NEO type.

The study team

QinetiQ N.Wells, C.White, A.Brown, R.Walher et al. - (Study lead, System and Spacecraft Lead)
PSSRI of The Open University J.Zarnecki, S.Green, A.Ball et al. (Science and payload lead)
Science Systems Limited (SSL) C. Lee, M. Townsend et al. (Ground system lead)
Telespazio E. Perozzi et al. (Specialist consultants on resonant orbit trajectories)
Politecnico di Milano F.Bernelli et al. (Specialist consultants on low-thrust trajectory optimisation)

Scientific objectives

"The proposal, a UK-Italian co-operation, addresses the issue of gaining an understanding of the diversity of the NEO population by employing a number of relatively small and low cost missions that individually encounter specific NEOs of interest. Such an approach requires the achievement of two major technical goals that in general characterise interplanetary missions: a high delta-V budget (needed for performing orbital manoeuvres) and a low-cost access to space (launchers are very expensive and consequently represent a high share of the total mission costs). Therefore the SIMONE proposal foresees the high performances guaranteed by the use of solar electric propulsion and the design of a spacecraft small enough to be considered as a secondary passenger (a so-called "piggyback") for large/medium size launchers. As an example a 120 kg SIMONE-type spacecraft can fit on the ASAP platform of the Ariane-5 - specifically designed to this end - thus exploiting the launching of a commercial satellite in orbit around the Earth. Escape to interplanetary space is then obtained by using the spacacraft's own propulsion system.

The selection of NEO candidates on the basis of both their scientific interest and their accessibility is also a critical issue. The distinction between "rendezvous" and "flyby" mission profiles is significant. A "rendezvous", where the spacecraft flies with or orbits the target NEO, delivers more scientific value than a flyby simply by virtue of the time spent in the vicinity of the object. However the delta-V requirement for a rendezvous can be much higher with respect to a flyby when high-eccentricity high-inclination target orbits are concerned, as it is often the case for NEOs. Therefore, the SIMONE proposal is for rendezvous missions wherever this is feasible. When the delta-V requirements turns out prohibitively high, an intermediate strategy is proposed: to synchronise the orbit of the spacecraft to that of the target object in order to allow multiple flybys, thereby maximising the scientific return. This "resonant flyby " strategy is similar to that successfully proposed in the early 1970s by Giuseppe Colombo during the NASA Mariner mission to Mercury and which allowed the spacecraft to flyby the planet three times.

from the article by Ettore Perozzi (Telespazio) an Nigel Wells (project manager of SIMON- QinetiQ), taken from Tumbling Stone's special issue Link to the full article

Project SIMONE in the media:

ESA's GSP web site (10/03/2003): "SIMONE" link

Tumbling Stone n.15 (25/07/2002) "The SIMONE concept: a fleet of small stallite exploring NEO's" by Ettore Perozzi (Telespazio): link

"Chasing Comets" from QinetiQ website: link

"SIMONE mission" from the Open University website: link

"SIMONE mission" from PSRI website: link

Downloads (click on the images to download ):

Image: artist impression of SIMONE - credits: QinetiQ