This paper reviews work that is being done in the area of hydrogen production for low power fuel cell applications (0.1-500W). It focuses on fuel reforming for these low power applications. It reviews many of the state of the art work being done.

Review of developments in portable hydrogen production using microreactor technology.

CubeSat evolution: Analyzing CubeSat capabilities for conducting science missions

This paper provides a comprehensive survey of spacecraft formation flying guidance (FTG). Here by the term guidance we mean both path planning and optimal, open loop control design.

A survey of spacecraft formation flying guidance and control (part 1): guidance

Microfluidic dye lasers three-dimensionally embedded in glass have been fabricated for what is believed to be the first time by integrating micro-optical and microfluidic components by use of a femtosecond laser. By pumping the microfluidic laser, in which the microfluidic chamber was filled with the laser dye Rhodamine 6G dissolved in ethanol, with a frequency-doubled Nd:yttrium aluminum garnet laser, lasing action was confirmed by analysis of the emission spectra at different pump powers. In addition, by arranging two microfluidic chambers serially in the glass, we built a microfluidic twin laser that produces an array of two simultaneous laser emissions with one pump laser.

Microfluidic laser embedded in glass by three-dimensional femtosecond laser microprocessing.

Small satellites are enabling multisatellite missions that were not otherwise possible because of their small size and modular nature [1]. Multiple small satellites can be flown instead of a much bigger and costlier conventional satellite for distributed sensing applications such as atmospheric sampling, distributed antennas [2], and synthetic apertures [3,4]. Missions with multiple small satellites can deliver a comparable or greater mission capability than a monolithic satellite, but with significantly enhanced flexibility (adaptability, scalability, evolvability, and maintainability) and robustness (reliability, survivability, and fault tolerance) [1,5]. Small satellites that weigh less than 10 kg can be broadly classified into nanosatellites (mass between 1 and 10 kg), picosatellites (mass between 0.1 and 1 kg), and femtosatellites (mass less than 100 g) [1,6].

Review of Formation Flying and Constellation Missions Using Nanosatellites

Integrated glass ceramic spacecraft include a plurality of glass ceramic components including molded, tempered, annealed, and patterned glass ceramic components coupled together for forming a support structure or frame or housing through which is communicated optical signals through an optical communications grid and electrical signals through an electrical communications grid, with the optical communications grid and electrical communication grid forming a composite electrooptical communications grid for spacecraft wide intercommunications. The support structure multifunctions as a frame, a housing, a support, a thermal control system, and as part of an electrooptical communications grid while encapsulating a plurality of optical, electronic, electrical, and MEMS devices between which is communicated the electrical and optical signals over the electrooptical communication grid.

Integrated glass ceramic systems

"Small Satellites" is the first book to describe the state of the art in microstats, nanostats, picostats, and CubeSats and the possible missions they can perform. More than two dozen internationally renowned contributors provide commentary on 50 years of history.

Small Satellites: Past, Present, and Future

A refrigerator apparatus includes a housing with an interior chamber, thermoelectric devices that are thermally coupled to the interior chamber, and dual redundant electronics configured to generate and apply input power to the thermoelectric devices.

Thermoelectric-based refrigerator apparatuses

In this presentation, we discuss the first demonstration of a lasercom downlink from a LEO 1.5U 2.3 kg CubeSat to our optical ground station at The Aerospace Corporation in El Segundo, CA. Two vehicles, AC7-B&C, built under NASA’s Optical Communications and Sensors Demonstration (OCSD) program and described in previous presentations, were launched in November 2017 and placed in a 450-km circular orbit. Following on-orbit checkouts and preliminary pointing calibration utilizing on-board star trackers, we have demonstrated (at the time of this manuscript submission) communications links up to 100 Mbps with bit error rates near 10-6 without any forward error correction. Further optimization of the vehicle pointing and detection electronics and operating the transmitter at its full power capacity should enable performance improvements and potential for higher data rates.

/pdf/optical-communications-downlink-from-a-1-5u-cubesat-ocsd-591kqhhg44.pdf

Optical communications downlink from a 1.5U Cubesat: OCSD program

The direct-write laser machining technique has been used to process a lithium- alumosilicate glass (FoturanTM) for an applicationwhich requires 3D patterned microstructures. Using two UV laser wavelengths (248nm and 355 nm), microcavities andmicrostructures have been fabricated for the development of microthrusters for attitude and orbit control of a 1kg class (10 cmdiameter) nanosatellite. In addition, experiments have been conducted to defme the processing window for the laser patterningtechnique. The results include a measure ofthe change in Foturan strength after a required program bake cycle plus HF etching ratesas a function ofthe laser repetition rate for the two UV wavelengths. INTRODUCTION Systems studies show that 21st century low-earth-orbiting (LEO) global communications and earth monitoring systems couldutilize constellations ofhundreds to thousands of individual spacecraft'. The feasibility of amassing and replenishing such largeconstellations will depend on the time and cost for manufacturing and launching individual spacecraft. Current spacecraftmanufacturing approaches lead to production and launch schedules which are measured in years with individual spacecraft costsranging from $1 million (a small limited-function LEO satellite) to well over $100 million (an advanced geosynchronouscommunications satellite) per spacecraft. Spacecraft manufacturing needs to become "faster and cheaper" to enable the massively-populated constellations ofthe future. One solution is to design spacecraft that are amenable to automated assembly and mass-production manufacturing techniques. A radical concept now under consideration is The Aerospace Corporation's Nanosatellitewhich leverages the processes and techniques developed by the microelectronics industry. Exploited to advantage are the automation,fabrication and assembly processes to produce a satellite which resembles a lap top computer in size and mass but is far moresophisticated in packaging. In essence, all the standard satellite subsystems, i.e., propulsion, attitude control, communications, etc.,are fabricated onto a series ofwafers which then get stacked to form a sandwich-like structure. Both monolithic and multichipmodule packaging can be used to integrate the electronics, sensors, microactuators and fluid delivery systems required for afunctioning satellite. Figure 1 shows an artist rendering ofthe Nanosatellite based on 10 cm diameter silicon (plus other materials)wafers. Glass, ceramic and polymeric materials are being considered to take advantage oftheir unique material properties2. Systemsengineering studies confirm that a satellite design as shown in Fig. 1 can conduct continuous global store-and-forwardcommunications and cloud-cover observation missions using 500 to 1000 satellites.The feasibility ofthe Nanosatellite to conduct missions beyond that ofjust a communications mailbox (i.e. store-and-forwardcommunications) will depend on the development of a micro propulsion system for attitude and orbit control3. We are developing UVlaser 3D patterning techniques to fabricate microstructures in alumosilicate glass (FoturanTM) to provide rapid microthrusterprototyping capability4. The techniques employ a high repetition rate UV laser and an XYZ microstepper positioner to selectivelyexpose Foturan without using a physical mask. Three dimensional structures can be fabricated by selecting a laser wavelength todefme the absorption depth, and by controlling both the photon dose and the spatial contour of the laser beam near its focus.Experiments at two laser wavelengths (248 nm and 355 nm) resulted in fabrication of mesoscale devices 400 or 1500 microns highhaving microscale structure lO5tips/cm2). The ability to work in glass permits the prototyping of differentmicrothruster types and other spacecraft subsystems. Microthrusters ranging from cold gas nozzles to ion engines will be necessary tomeet the diverse propulsion requirements of future Nanosatellite missions.Person to whom correspondence should be addressed

Siegfried W. Janson

Papers

Integrated glass ceramic systems

Small Satellites: Past, Present, and Future

Thermoelectric-based refrigerator apparatuses

Optical communications downlink from a 1.5U Cubesat: OCSD program

Direct-write UV-laser microfabrication of 3D structures in lithium-aluminosilicate glass