The Draper Technology Digest - Draper Laboratory

FIGURE 5. Apollo 14 astronaut Ed Mitchell consults his mapto navigate back to the lander after a failed attempt to reachCone Crater.FIGURE 6. ChipSat conceptual design utilizing a swarm of wafersizedspacecraft to accomplish a mission at Mars [9].the primary ADCS electronics. This gives the payloadindependence, allowing for the spacecraft bus to take careof primary functions.Precision Pointing of Payloads and AntennaA variety of spacecraft exists where devices, e.g.,communications antennae, cameras, scientificinstrumentation, etc., need to be inertially pointed tocarry out a mission. The MEMS gyro-enabled MGUcould be mounted coincident with the device to bepointed, letting a pointing control loop be closed directlyover the device.Hosting the ChipSat MissionA new class of “ChipSat” missions is being exploredwhere the spacecraft is primarily a silicon wafer capableof performing communications, power generation,and attitude control to support a mission in the spaceenvironment. As depicted in Figure 6, a typical missionconcept consists of hundreds, even thousands, of theseChipSats being dispersed in orbit to perform its primarymission: communications, earth science, monitoring,reconnaissance, etc. [10]. MEMS gyros and theirprocesses directly support the ChipSat thrust, for it ispossible to not only have miniature rate sensing on achip, but also to collocate that rate sensing with otherMEMS devices on the same wafer. The MEMS itself isthe spacecraft!One approach to achieving true “satellite-on-achip”capability is by the homogeneous integrationof traditional spacecraft elements (command anddata handling (C&DH), power, comms, ADCS,storage, etc.) into a single substrate. However, amore effective approach is to use heterogeneouswafer-scale integration with discrete componentsincorporated into a pseudo-wafer and processed usingtraditional wafer fabrication techniques in which thecomponents themselves have been fabricated usingthe most appropriate technology for the function.Over the past 15 years, Draper has addressed theneed for ultraminiature heterogeneous systems bydeveloping a deposited multichip module (MCM-d)process that is a hybrid of printed circuit board andwafer fabrication techniques. More recently, Draperhas achieved even higher component density withthe integrated ultrahigh-density (i-UHD) process,a hybrid of MCM-d and advanced complementarymetal oxide semiconductor (CMOS) and MEMSfabrication methods. Using these processes,Expanding the Spacecraft Application Base with MEMS Gyros35