About this Article
Written by: Andrew Bauer
Written on: October 12th, 2005
Tags: aerospace engineering
Thumbnail by: Wikimedia Commons
About the Author
Andrew Bauer was an aerospace engineering student at the Viterbi School of Engineering at the University of Southern California in the fall of 2005. He is from West Virginia.
Also in this Issue
American Football: That Magic Yellow LineWritten by: Jeff Braun
SamplersWritten by: Mingfei Mike Gao
The Engineering Behind SurfingWritten by: Anthony Edwards
The Little Plastic BulbWritten by: Tian Li Woon
Stay Connected

Volume VII Issue III > Micropropulsion and the Future of Space Exploration
An emerging trend in the space industry today is the shift from large satellites to smaller microsatellites. It is envisioned that groups of microsatellites could communicate with each other, allowing them to increase their functionality and creating very adaptable networks that could replace the functions of larger, more complex spacecraft. The stringent power, weight, and space requirements of these microsatellites create a need for new small scale propulsion methods. Widely used chemical rocket engines, both mono- and multi-propellant, are being scaled down for use on microspacecraft. A more experimental approach involves the use of MEMS technology to create compact thrusters. Resistojets, ion engines, chemical rockets, and other systems are all being modified and scaled using MEMS technology to create useful new methods of micropropulsion.
When most people are asked to think about the future of space exploration, they probably conjure mental images straight out of one of the many science fiction films that address the subject. One might imagine huge starships carrying thousands of people from planet to planet, with massive glowing engines and possibly some kind of ''warp drive'' propelling them at the speed of light. Ask an engineer, however, and one would probably get a dramatically different response. When engineers today consider the future of spaceflight, they are beginning to think much smaller. There has recently been a great deal of interest among members of the scientific community in building microspacecraft, space vehicles that weigh less than 100 kilograms [1]. Though these tiny spacecraft cannot carry passengers and certainly have no space for huge engines, they are quickly becoming the future of space exploration.

Bigger Is Not Always Better

There are many advantages to using microspacecraft instead of the more conventional large satellites and space vehicles. Microspacecraft are lighter and therefore far easier and cheaper to launch. Additionally, a platoon or constellation of microspacecraft can link together to perform the same tasks that a larger satellite might [2]. This offers the advantage that, if a single element of the system is damaged, only one of the microspacecraft must be replaced to restore functionality. In contrast, if part of a large satellite is damaged, often the entire spacecraft must be replaced or a costly and dangerous repair mission must be initiated. Besides replacing larger, more complicated satellites, groups of microspacecraft can also be used to monitor and repair other spacecraft, like the Space Shuttle or the International Space Station [3]. For example, imagine a network of microspacecraft that could fly around the space shuttle, detecting and repairing damage to its hull. These spacecraft could easily prevent disasters like the recent Columbia explosion and eliminate the need for dangerous spacewalks, such as those used during the recent flight of Discovery or those used to repair the Hubble Space Telescope.
While engineers might primarily be interested in microspacecrafts because of their simplicity, American taxpayers will be interested in microspacecrafts because they will be getting more for their money - the simplicity in design decreases the cost of spaceflight while increasing the amount of scientific knowledge gained per mission. Although the price of spaceflight might seem like a distant, unfamiliar issue to most Americans, reducing the cost will actually have a huge effect on the lives of many people. For example, communication satellites power services like cellular phones, satellite television, Internet, and radio, and reducing the cost while increasing the reliability of these satellites can only be beneficial to users. Beyond simple convenience, satellites are responsible for various types of valuable research that affect people's everyday lives. Satellites monitor weather patterns, track ocean currents, and create increasingly accurate maps of the earth, thereby improving our understanding of the world around us. This understanding could one day increase our ability to predict events like the deadly Gulf Coast hurricanes or to understand the effects of global warming. Imagine the effect on scientific progress as satellites become cheaper and easier to produce, launch, and maintain; this is exactly the impact that microspacecraft may have as they increase in prominence.

So About that Warp Drive...

One of the most enduring images associated with space flight is the massive fiery launch of a rocket or Space Shuttle. As one might expect, however, this large, spectacular form of propulsion is not really suited to tiny microspacecraft. As such, one of the most challenging obstacles engineers must overcome in order to make the microspacecraft dream a reality is the development of a useful propulsion system that is small and simple. Additionally, the system must be designed to use little power, as space for solar cells and other power supplies is limited on a tiny spacecraft. With these constraints in mind, there are a number of systems that are being developed for use on microspacecraft. These systems may seem unspectacular - in fact, many of them produce so little thrust that it would be imperceptible even if you put your hand right next to them - but they are really quite useful for maneuvering a tiny spacecraft in the vacuum of space.