Page 130 - MEMS and Microstructures in Aerospace Applications

Osiander / MEMS and microstructures in Aerospace applications DK3181_c006 Final Proof page 119 2.9.2005 9:38am

Microtechnologies for Space Systems 119

FIGURE 6.6 Optical micrograph of the NASA Glenn Research Center Hydrogen Sensor.
The device consists of Pd alloy-based resistor and metal-oxide-semiconductor hydrogen
sensors. Also incorporated on the chip are a microfabricated heater and temperature sensor
for thermal control of the sensor. (Source: NASA Glenn, www.grc.nasa.gov/WWW/RT1999/
5000/5510hunter.html.)

low mass, size, and power, and can be integrated with miniaturized electronics for
signal processing and temperature control. The GRC sensor has also been delivered
to the X-33 and X-43 projects and has been baselined for use in the water processing
and oxygen generator on the International Space Station. The GRC chip contains
two Pd-alloy-based hydrogen sensors. These are a resistor and a metal-oxide-
semiconductor device. Also integrated within the chip are a resistive heater and a
temperature sensor for controlling the thermal environment of the sensor.

6.2.8 MEMS VARIABLE EMITTANCE CONTROL INSTRUMENT
This MEMS-enabled instrument described in detail elsewhere in this book contains
16
a MEMS shutter array radiator that allows tunable control of the radiative
properties of spacecraft skins. The project is led by NASA GSFC in partnership
with The Johns Hopkins University Applied Physics Laboratory and Sandia
National Laboratories. The technology is based on an array of micromachined,
hinged shutters that can be opened or closed using MEMS comb drives (maximum
operating voltage: 60 V), thus presenting a variable emittance surface to the outside
environment for the spacecraft. Each shutter is a 1.77 0.88 mm rectangular
surface. The entire shutter array contains a total of 2592 such shutters (36 chips,

© 2006 by Taylor & Francis Group, LLC