Volume 12, Number 1

12_1 cover

Detection of Biological Agents
Charles A. Primmerman

Biological weapons pose a real and potentially immediate threat. They are relatively cheap to manufacture and employ, and they have tremendous potential impact as terror weapons. These features make biological weapons attractive to rogue states and terrorist organizations. In this article we briefly describe the threat of biological weapons. We then describe Lincoln Laboratory work in developing advanced sensors to help combat the threat of biological weapons. These sensors include an early-warning sensor that can sense small quantities of biological particles in the air and issue an alarm in less than one minute and a bioelectronic identifying sensor that can potentially identify a biological agent from a single sensed particle.

Meteor Shower Characterization at Kwajalein Missile Range
Sigrid Close, Stephen M. Hunt, Michael J. Minardi, and Fred M. McKeen

One billion meteoroids enter the Earth's atmosphere daily, and their potential impact on spacecraft is not yet well characterized. Kwajalein Missile Range radar systems have contributed new information on meteor phenomena, including observations of the Perseid and Leonid meteor showers of 1998. Initially, Perseid data were collected by using the ALTAIR radar, a two-frequency radar uniquely suited for detecting meteor head echoes. Shortly after the Perseid observations, Leonid data were collected by using ALTAIR and other Kwajalein sensors at microwave and optical frequencies. This article contains an analysis of Perseid data collected at VHF. Meteor head-echo statistics are presented, with an in-depth analysis of a few select head echoes to estimate decelerations and densities. Head-echo data collected at three frequencies and ionized meteor trail data from the Leonid shower are also presented.

Equatorial Atmospheric and Ionospheric Modeling at Kwajalein Missile Range
Stephen M. Hunt, Sigrid Close, Anthea J. Coster, Eric Stevens, Linda M. Schuett, and Anthony Vardaro

During the last peak of the solar activity cycle, in the late 1980s and early 1990s, spatial and temporal variations of the equatorial ionosphere impacted the measurement accuracy of the ALTAIR radar at Kwajalein Missile Range (KMR) because of poorly modeled ionospheric range and elevation-angle bias errors. As missile-reentry-vehicle and space-surveillance missions have developed at KMR, improvements in measurement accuracy have shown that unmodeled atmospheric refraction is the principal error source limiting sensor accuracy. Modeling the equatorial ionospheric activity and then removing its effect on KMR data is particularly challenging, since the radar is located beneath a complex region of the earth's ionosphere. An effort to characterize ionospheric conditions in real time has resulted in the ionospheric error-correction model, or IECM. Representative equatorial ionospheric data are presented along with an evaluation of the IECM at removing these range and elevation-angle bias errors.

Information Survivability for Mobile Wireless Systems
Thomas M. Parks and Clifford J. Weinstein

Mobile wireless networks are more vulnerable to cyber attack and more difficult to defend than conventional wired networks. In discussing security and survivability issues in mobile wireless networks, we focus here on group communication, as applied to multimedia conferencing. The need to conserve resources in wireless networks encourages the use of multicast protocols for group communication, which introduces additional security concerns. We point out the need for rate-adaptation techniques to simultaneously support multiple receivers that each experience different network conditions. We also identify several security issues for reliable group communication, providing examples of denial-of-service attacks and describing appropriate security measures to guard against such attacks. Finally, we introduce a survivability approach called dynamically deployed protocols. We suggest that this dynamic protocol deployment can be achieved effectively by transmission of in-line mobile code.

top of page