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Strofio: Exospheric Sampling of Mercury's Surface Composition. US involvement in BepiColombo and SERENA-STROFIO prospects. Stefano A. Livi Southwest Research Institute Stefano.Livi@swri.edu 210-522-3310. Mercury’s Exosphere. Difficult to study as Mercury is very near the Sun
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US involvement in BepiColombo and SERENA-STROFIO prospects
Stefano A. Livi
Southwest Research Institute
Together, these six elements account for only 20% of the observed total pressure inferred from radio occultation measurements.
Thermal evaporation (day/night asymmetry)
H, He, Na (subsolar), K (subsolar), S, Ar, H2O
Photo-desorption: (day/night asymmetry)
Important for volatiles
H, He, Na, K, S
Ion-sputter: (Solar wind activity related)
Important for refractories
Ca and others
Impact Vaporization (episodic)
Everything? (more volatiles than refractories)
Important for creation of glass
Important for loss of water deposits and volatiles
Venting, volcanism (spatially locked)
everything? (more volatiles than refractories)
Strofio is a scientific investigation of the Hermean exosphere based on a novel mass spectrograph that determines particle mass-per-charge (m/q) by a time-of-flight (TOF) technique.
The name comes from the Greek word Strofi, which means “to rotate”: the phase of a rotating electric field “stamps” a start time on the particles’ trajectory. The detector records the exit position (hence the start time) and the stop time.
Strofio accomplishes its high-sensitivity (0.14 counts/s when the density is 1 particle/cm3) within very limited resources (1.9 kg).
The mass resolution (m/m≥ 60) is achieved by fast electronics and does not require tight mechanical tolerances.
Based On a review of NASA's requirements, the Science Mission Directorate has decided to further evaluate the technology readiness of Strofio for flight on the European Space Agency's Beppi-Colombo mission to Mercury. The evaluation will be based on a Technology Readiness Report and a site visit. The review will be performed by a team of scientists and engineers external to NASA. The results of the evaluation will be communicated to the Directorate Program Management Council who will decide if Strofio will be selected to proceed into Phase A.
NASA's final decision regarding Strofio will be communicated to you and ESA on October 31,2007.
Technology Readiness Report issued
Questions from the review team received
Technology Readiness Review takes place
October 31st: Report from the evaluation committee (distributed on 3/17/2008 !!):
The Strofio instrument risk is rated as MEDIUM. There are 3 major weaknesses driving the medium risk rating. The proposed schedule is aggressive and lags the ESA schedule, which could negatively impact Strofio. The mass margin is inadequate at this stage of development and not under the control of Strofio. Also, the Phase C/D cost reserves are only 20% as calculated by the TMC panel, compared to the 25% required by the AO. However, there are two major strengths that are mitigating factors. The instrument concept is well suited to obtain the required measurements and the proposing team is highly qualified to do the implementation. The TMC Panel feels that with careful coordination with ESA/SERENA and with dedicated mass margin allocation, the instrument can be successfully implemented for BepiColombo.
November 14th :
The late autumn and early winter months are a time of great budget uncertainty at NASA. The President's 2009 Budget Proposal is not presented to Congress until early February. Before that, NASA must negotiate its portion of the 2009 Budget with the Office of Management and Budget. Those negotiations are currently incomplete. Due to this uncertainty, NASA cannot, in all prudence, undertake any new commitments at this time.
Budget is signed by pres. Bush
ASI contact with Jim Green:
My personal reading of the tea leaves: