Fusing Micromachine and Space
Development Technologies
Ichiro Nakatani
Institute of Space and Astronautical Science
performed on methods of ejecting a liquid by applying heat with amicroheater, microthrusters employing an array of micro-solid propellant ,and methods for obtaining an efficient microforce by accelerating ions in apulse, these technologies still require much development effort before being
used in real space missions.
Additional research is being conducted on applications of micromachinetechnology on a wide range of components for use in space, including relays
and switches, filters, pumps, DC/DC converters, and solar cells.
Micromachine technology is extremely compatible with spacedevelopment where developing smaller equipment is a key issue. It is essential
to promote communication between space engineers on the needs side andmicromachine engineers on the seeds side. Many in the space community
share a sense of crisis in having fallen behind America and, therefore, a strong
sense of urgency to construct compact space equipment. On the other hand,
Japanese ground researchers in micromachines possess some of the world's top
level techniques and hope to expand their applications. Therefore,communication between the two parties should be extremely beneficial to both.
Equipment used in space requires an extremely high level of reliability tooperate in such severe conditions as vacuums, high temperatures, lowtemperatures, radiation, vibration and shock during launch. Attempting toclear these hurdles is a positive goal for ground micromachine technologies.

Launching satellites into orbit currently requires several million yen per
kilogram. As a result, developing lighter, smaller and less power consuming
and more compact onboard equipment has been one of the most important
issues in space development.
The U.S. is far ahead in R&D on applications of micromachinetechnology in space. While it is common knowledge that conventional
satellites weigh from several hundred kilograms to several tons, designs for
manufacturing a one-kilogram satellite primarily from silicon material havebeen published. Most functions required by a satellite-i.e. sensing, attitudecontrol, data processing, communications, command processing, power
supply, solar cells, thermal control, structure, and the like-can in principle becreated on a silicon substrate using semiconductor lithography.
Accelerometers, gyros, infrared sensors, and microgravity sensors that
apply micromachine technologies being developed on the ground are also
being studied for an extremely large broad of space applications. Many are
already at a stage of practical use in space.
On the other hand, microthrusters used for orbit and attitude control
are considered important as being unique to space. There have been many
published researches on the application of micromachine technology to thedevelopment of valves and nozzles, such as cold gas jet thrusters that ejectcompressed gas from nozzles at a high speed. While much research has been

Investigative Study into the Integration ofMicro-Flying & Micromachine Technologies
Isao Shimoyama
Professor,
Department of Mechano-Informatics,
School of Information Science and Technology, The University of Tokyo
Next, we studied the development of micro-actuators for application tosmall flying devices. Generally speaking, if the scale of the flying object issmall, the actuation suitable for this object will also change accordingly.
During this study, we investigated both the effect of reducing the scale of theactuation as used in jets and other modern aircraft, and also flapping andother types of actuation unique to small flying devices. In terms of achieving
the driving forces required to allow flight, many reports have dealt withpropulsion using propellers and jets. And while research into flapping-wing
type propulsion continues, many problems remain to be overcome before thistechnology may be put to practical use. A method for the supply of energy
will also be required so that flight may be achieved, and technologies such as
solar batteries, microwaves, and polymer batteries are expected to proveuseful in this regard. In the case of jet propulsion, however, the combustionof chemical fuels is an efficient means of propulsion.
Finally, we carried out an investigation into the sensors generally used
in today's airplanes and also into those sensors which can be used in thecontrol of small flying devices. Research has been carried out regarding
visual sensors, accelerometer-type sensors, GPS, laser scanners, altimeters,
and the like; furthermore, these are currently being put to use inautonomous helicopters. This type of element is crucial in the control of theposition and attitude of the device, and valuable research in this field is
expected to increase in the future.

It has been considered from the beginning of the development of
micromachines that small flying devices could be used in the retrieval of
information from disaster areas, nuclear power-generation plants, and otherlocations for which access may be difficult. Furthermore, a number of such
unmanned flying devices are now being put to use in disaster areas and othersimilar locations. As element technologies for this type of small flying device,micromachine technologies including micro actuators and micro sensors arerequired.
In this research, we first conducted an investigation into the current
state of unmanned aerial vehicles(UAV) which are now being put to practicaluse. The UAVs covered in this report vary from several tens of centimeters
to approximately one meter in size. In Japan, these small UAVs are usedduring volcanic eruptions to photograph the areas of damage around thevolcano's crater, to measure the thickness of volcanic-ash buildups, and forother similar tasks. Overseas, on the other hand, research and development
is also being carried out for military purposes, and in recent years, thistechnology has been implemented for border security, highway patrol
activities, narcotics control, waterway administration, and fire-prevention
activities among others. Fundamental research is progressing in terms of
aerodynamics for low Reynolds numbers, and recently, as a result of theattention being paid to the wings of insects of an identical size, research isalso being carried out on flapping-wing flight for low Reynolds numbers.

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