Airborne SOFIA Telescope

Telescope Balancing Testbed

Innovative contact and noncontact sensors for measuring telescope imbalance

Schematic of the Kuiper Telescope
(Click on image for larger view)

OBJECTIVES:
Increase the accuracy and efficiency of balancing the SOFIA telescope:

The Smart Systems Research Lab at NASA Ames Research Center is developing innovative methodologies and advanced software tools for balancing the SOFIA telescope precisely and efficiently.

Balancing the Kuiper telescope (SOFIA's predecessor) was a very difficult and challenging task. Balancing the SOFIA telescope will be even more problematic because of its larger size. What is needed are technologies that will enable 1) rapid pre-flight telescope balancing, and 2) real-time in-flight dynamic telescope balancing. During flight, nonlinear effects such as cryogenic boil-off, varying forces from tethered data and power cables, and varying aerodynamics loads will affect telescope-pointing performance if left unabated.

We have successfully developed an innovative pre-flight telescope balancing methodology that can rapidly and accurately balance a prototype telescope to within a mass of ~5 grams at a radius of one meter from the center of the spherical bearing when an unknown imbalance weight is placed in it. The prototype telescope is a 1/2 scale model of the Kuiper telescope. The prototype telescope's spherical bearing provides a high fidelity simulation of the performance of the Kuiper telescope's spherical air bearing. This technology will enable pre-flight balancing of the SOFIA telescope to be performed accurately and rapidly.

Development of in-flight dynamic balancing technologies for the SOFIA telescope is currently on hold, pending funding support.