Major Areas of Opportunity - Implications of Emerging Micro-and Nanotechnologies - page 104

A revolutionary application enabled by MEMS liquid rocket engines would
be microlaunch vehicles and ballistic, multistage missiles in the size range be-
tween 15 and 800 kilogram gross liftoff weight (GLOW). Design studies suggest,
for example, that a 60-kilogram GLOW two-stage rocket could deliver a kilo-
gram or two to low Earth orbit or twice that as a ballistic payload to a 4,500-
nautical-mile range. Except for the seeker, these vehicles would be about the size
and complexity of a tactical missile and thus should cost about the same. They
could be ground or air launched. As a launch vehicle, the microrocket redefines
the concept of low-cost access to space as cost per mission rather than cost per
pound of payload (these are about the same for large rockets). Thus, it will be
possible to place a payload (albeit a small one) into orbit for $10,000 to $50,000
rather than the $10 million to $50 million cost today. This cost is low enough that
launchers can be stockpiled for on-demand launch access to space and deployed
across the planet for tactical missions. Aggressive orbital applications might
include such military missions as visual and IR inspection of space objects,
jamming of communications satellites, electronic intelligence gathering, and anti-
satellite operations. More peaceful military applications could include distributed
space weather monitoring during geomagnetic storms and low-resolution (>50-
meter ground resolution) Earth observation. Presumably, scientific and commer-
cial users of space would adapt their missions to take advantage of this very low
cost as well. Suborbital uses might include ultralong-range micro tactical ballistic
missiles with sensor or nonnuclear munitions payloads, ballistic imaging or elec-
tronic intelligence payloads that loiter for 10 minutes above a battlefield, and
very small antiballistic missile interceptor missiles. Micro- and nanoelectronics
and MEMS can provide ultrasmall intelligent payloads that are ideally suited to
micro launch vehicles.
Spacecraft Propulsion
Chemical Propulsion
MEMS-scale liquid propellant rocket engines offer significant evolutionary
advantages over conventional engines and also enable new space systems con-
cepts. MEMS-based thrusters with ultrasmall micro- to millinewton thrust levels
are needed for emerging micro-, nano-, and picosatellites. Thrusts of 1 to 5
pounds (4.5 to 23 newtons) are currently used for station-keeping by large geo-
synchronous satellites, while hundreds of pounds of thrust are needed for impul-
sive orbital maneuvers such as the apogee kick burn required to transfer a satellite
from geosynchronous transfer orbit (GTO) to final GEO. Thrusters for kinetic-
kill vehicles can fall in between. Cube-square scaling implies that a MEMS
machine will have at least an order of magnitude higher thrust-to-weight ratio
than a large rocket engine. The reduced weight can be used for increased payload
or for redundancy to improve reliability. MEMS also facilitates the commoditi-