[Editors] MIT upgrades Sputnik-era antenna

[Jen Hirsch]

FOR IMMEDIATE RELEASE
Wednesday, August 13, 2008

Contact: Jen Hirsch, MIT News Office
T. 617-253-1682, E. jfhirsch at mit.edu

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MIT's Lincoln Laboratory upgrades Sputnik-era antenna
--Principal tool for maintaining the Deep Space Catalog working  
better than ever
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CAMBRIDGE, Mass. -- A mammoth MIT antenna installed in 1957 as the  
first radar system to conduct space surveillance (it observed the  
Sputnik satellite) is poised for many more years of key observations  
thanks to a recently completed renovation.

Lincoln Laboratory's Millstone Hill Radar (MHR) antenna is one of the  
world's principal tools for maintaining the Deep Space Catalog--the  
listing of the more than 3000 objects circling the Earth 40,000 km  
away in geosynchronous earth orbit (GEO). Together with two other  
surveillance radars--ARPA Long-Range Tracking and Instrumentation  
Radar (ALTAIR, in the Marshall Islands) and Globus II (in Norway), it  
monitors the increasingly cluttered geosynchronous orbit to reduce  
the probability of collisions. The three also monitor satellite and  
spacecraft launches.

But the venerable MHR system was showing its age. The motors and  
motor generators replaced in this renovation were original 1950s era  
equipment. "They were past their end of life. The motors were worn  
from years of use and regular rebuilds, and the inefficient motor  
generators were failing frequently," says Paula Ward of Lincoln's  
Control Systems Engineering group. Each failure would shut down the  
antenna for a significant period of time.

Now the system, which consists of an 84-foot-diameter (25 m)  
reflector supported by a tower a little over 85 feet high (26 m), is  
easier to troubleshoot, and downtime can be kept to a minimum.

Jeff Dominick, the site manager of the Lincoln Space Surveillance  
Complex (LSSC) that includes MHR, stresses the importance of MHR to  
LSSC and how important LSSC, in turn, is to the Air Force Space  
Command. "Losing MHR for any period of time would impact our ability  
to track in this region," he says, pointing to the arc of GEO above  
the United States that isn't covered by ALTAIR and Globus II.

As project lead of the recent upgrade, Ward was working with two  
extremes--very heavy and bulky motors and gear boxes, and new  
software controls running in a real-time embedded environment.

For example, installing and aligning the new motors and gear boxes  
was challenging since no mechanical computer-aided-design models  
existed. At the other end of the spectrum, while many upgrades had  
been done to the radar system and associated computers over the  
years, the antenna control system had been upgraded only twice in the  
last fifty years.

Prior to the upgrade, an operator needing to move the antenna for  
maintenance had to turn mechanical knobs to rotate the antenna and  
read meters on a panel indicating positions. Now the interface is  
more intuitive and is done on a laptop. The operator simply sets the  
desired positions, and clicks Run. In addition, the upgraded system  
provides, for the first time, remote access to the antenna's local  
displays.

Dominick concludes, "We're trying to reduce the probability of  
collisions. This upgrade has significantly reduced downtime and  
maintenance tasks associated with the MHR antenna control system."

By Gregory P. Hamill, MIT Lincoln Laboratory

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