Major Areas of Opportunity - Implications of Emerging Micro-and Nanotechnologies - page 76

and toxic chemical release (e.g., HCl from a solid booster) are needed in conjunc-
tion with the launch vehicle monitoring system to dramatically increase the aware-
ness of vehicle status and the launch site environment. MEMS sensors coupled to
data transceivers can be used in a wireless network system onboard the vehicle
and on the launch site. The telemetry data can channel real-time or near-real-time
information to a ground-based data storage system for postlaunch review.
Another important role for micro- and nanotechnology in both satellite and
on-orbit manned vehicle operations is in condition-based maintenance (CBM)
status and health monitoring systems. These systems could save future costs by
fault detection and isolation and by enabling automated self-test and repair ac-
tions to take place. The CBM protocol also enables safer operations as well as
increased system availability in contrast to a failure-based maintenance protocol
scheme. Reuseable launch vehicles are prime candidates for CBM. One relatively
common malfunction in spacecraft is the failure of a high-speed bearing, reaction
wheel (i.e., momentum wheel), or gyro bearing. Bearing degradation can often be
anticipated by monitoring vibration signatures; this would be an excellent appli-
cation for a micromachined accelerometer coupled to a digital signal processor or
microprocessor in an application-specific integrated microinstrument (ASIM).
Corrective action could consist of the metered release of lubricant via a fluidic
ASIM. Smart bearings, smart structures, and multifunction structures are already
being considered by space engineers. These ideas have also been considered in
the aerospace community for developing adaptive structures that have embedded
sensors, actuators, controllers, and processors.
Distributed Sensor Systems
Swarms of sensors can provide additional value by simply providing suffi-
cient coverage. One obvious example is dense sensor arrays for space weather
forecasting. 133 However, swarms of sensor suites can also provide a more com-
plete information space for other purposes, including building a spaceborne
equivalent of the Very Large Array (VLA) (Figure 3-13). The VLA consists of 27
radio antennas in a Y-shaped pattern just west of Socorro, New Mexico. A
spaceborne VLA could be sized to aim not out into space but at Earth's surface.
FIGURE 3-13 The Very Large Array. SOURCE: Photo by Dave Finley, NRAO/AUI.