The Ohio State University College of Mathematical & Physical Sciences Department of Astronomy

Attendees: Pat Osmer, Bruce Atwood, Tom O'Brien, Mark Derwent, Darren DePoy, Jen Marshall & Rick Pogge,

Detectors

Bruce Atwood has a chance to buy a Marconi LLLCCD60, which would be used in the wavefront sensor we need to provide for MODS. We gave him the go-ahead to purchase this unit (it's a development kit).

Mechanical

Tom has finished the grating turret support design (where it mates to the MODS structure). Is working on the design of a handling fixture, and working out the handling procedures.

A bid package for the grating carts has been prepared to get an idea for what they will cost (including painting). Will also be sending out an RFQ to various local shops for fabrication of the top structure of MODS (made from stainless steel tubes).

Tom also reported on carbon fiber tubes for the collimator truss members. Cost will be in the $10-20K range, and will result in additional design and materials costs (hard to predict) because more complex joints and other mounting fixtures will be required. The material properties of the tubes is slightly disappointing. They only end up having about half of the stiffness of the steel tubes due to two factors: the winding angle and the epoxy used to bond the fibers.

The real figure of merit, though, is the stiffness-to-weight ratio. Now that we have some real numbers to work with, Tom will run FEA models to assess their expected flexure performance. Even with carbon-fiber tubes, the flexure motions will still be dominated by the self-weight of the tubes proper. Tom will also explore designs that will keep the structure open to possible retrofit of an initial steel structure with carbon fiber tubes, should the latter introduce unacceptable delays in deploying the first-phase MODS.

The SPIE meeting in August will feature a number of MODS and MODS related posters. Darren took care of sending in the abstracts. More later when we hear which papers were accepted.

The next meeting will be early March after various people return from travel.

R. Pogge, 2002 March 1