Lobster-ISS was an X-ray mission initially proposed by an International collaboration led by George Fraser (University of Leicester, UK) in response to the ESA call for two flexi-missions (F2 and F3) for the International Space Station (ISS). The project has been approved for an industrial phase A study funded by ESA (started in July 2002, contractor Gavazzi Space Milano) for accomodation on board the ISS Columbus External Payload Facility (CEPF), with launch scheduled for 2008-2009 and a nominal duration of 3 years. The main scientific objective of Lobster-ISS is the mapping of the X-ray sky in the 0.1-3.5 keV energy band with an angular resolution as low as 4-6 arcmin and a daily sensitivity of 2x10-12 erg cm-2 s-1. The main instrument is based on Micro-Channel Plate (MCP) optics in a Lobster-eye configuration and focal plane detectors based on special sensitive proportional counters. It will be composed by six identical modules with FOV = 27x22.5 degrees each, misaligned in such a way to give a total rectangular field of view of 22.5 degrees in the direction of the ISS motus and 162 degrees in the direction perpendicular to it. Thanks to the orbital motion of the ISS it will be possible to map almost the sky every ~90 minutes, allowing the creation of a catalogue of 250000 sources every two months. The combination of the wide field of view, the good angular resolution and high sensitivity will allow the study of many high energy astrophysical sources, from comets to stellar coronae, X--ray binaries, soft X-rays transients, SN explosions, AGN, diffuse X-ray background and Gamma-Ray Bursts. See the Lobster-ISS science case for more details (PDF)
The Lobster-ISS project, in addition to the X-ray optics, includes the development of a Gamma-Ray Burst Monitor (GRBM) with the minimum goal of identifying the GRBs detected by the X-ray telescope. The X-ray astronomy group at IASF/BO, along with University of Ferrara and University of Urbino, coordinated by F. Frontera, has performed the definition study of this GRBM for the phase A of Lobster-ISS. The instrument proposed not only satisfies the above mentioned minimum goal, but significantly extends the science objectives of the Lobster-ISS mission. The GRBM consists of 4 misaligned detection units, each one made of an array of Peltier-cooled CdZnTe, surmounted by a passive collimator which defines the field of view. The FOV of each unit is 35 x 55 degrees (FWHM), resulting in a total rectangular field of view of 35 degrees in the direction of the ISS motion and 240 degrees in the direction perpendicular to it. The collimators allow to reduce the background level and, combined with the units misaligment, to reconstruct the burst positions within few degrees depending on the burst intensity. The GRB alerts provided by the GRBM, along with their coordinates, are automatically transmitted to the Lobster data handling electonics for a better determination of the GRB positions by means of the X-ray telescope. The energy passband of the GRBM (3 - 300 keV), partially overlaps the Lobster X-ray telescope passband (0.1-3.5 keV) and covers the energy range in which GRBs emit most of their energy. In this way, the Lobster-ISS passband (0.1 - 300 keV) is the broadest never used before for an all-sky monitor to study the prompt emission of GRBs. The very good energy resolution, 3% at 6 keV, will allow a sensitive study of cut-offs in the spectra of GRBs and transient absorption and/or emission features during the early phase of the prompt emission. As demonstrated by BeppoSAX results, the study of these features and cut-offs is of key importance for the study of the circum-burst environment, the nature of progenitors, the connection with SNe. In the described configuration, Lobster-ISS is the ideal mission for studying also X-Ray Flashes (XRFs) and their nature. In addition to GRBs and XRFs, the GRBM will allow the identification and study of all types of fast high energy X-ray transients, in particular Soft Gamma Repeaters. See the Lobster-ISS GRBM science case for more details (PDF)
(Sketch of a possible configuration of the Lobster-ISS instrument. Courtesy of Carlo Gavazzi Space)
The phase A study of Lobster-ISS was formally completed at the phase A review board
meeting of February 16, 2005 and Lobster declared technically ready to proceed to phase B. However, due to well known problem with the managing of the ISS (following the NASA space Shuttle disaster in 2003), the ESA flexi missions program was stopped.
Following this, Lobster and ROSITA (a MPE led experiment which was also originally
proposed for the ISS) entered the consortium supporting the "resorted"
mission. Lobster was renamed LWFT, and its final inclusion in the Spectrum X-Gamma
payload is subject to financial support from the UK funding agency STFC (the
successor to PPARC).
In 2007, the Italian collaboration who participated to the Losbter-ISS phase A received, in the framework of ASI/INAF contract I/088/06/0, a small financial support to investigate the possible Italian participation to LWFT.
(Sketch of a possible configuration of the Spectrum-RG payload. A possible allocation of the GRBM modules is to flank one of them to each of the LWFT modeules.)
F. Frontera (INAF/IASF Bologna and University of Ferrara), L. Amati, N. Auricchio, A. Basili, E. Caroli, F. Fuschino, C. Labanti, G. Landini, M. Marisaldi, N. Masetti, M. Orlandini, E. Palazzi, S. Silvestri, J. Stephen, G. Ventura (INAF/IASF Bologna), G. Di Domenico, C. Guidorzi, G. Loffredo, E. Montanari (University of Ferrara), G. Bogliolo (University of Urbino)
Lobster-ISS Science Case
GRBM Science case
GRBM Definition Document
"The gamma-ray burst monitor for Lobster-ISS" (Advances in Space Research, 2007, 38, 1333)
Lobster-ISS Home Page at University of Leicester
LWFT page at Leicester University
Spectrum-RG page at IKI
Page mantained by: L. Amati & N. Auricchio
Last update: November 7, 2007