REDSTONE ARSENAL, Alabama -- When designing a satellite for space you need to design a ground antenna to track it.
To track the Kestrel Eye satellite as it prepares to orbit in space, members of the U.S. Army Space and Missile Defense Command/Army Forces Strategic Command Technical Center designed the Warfighter Assisting Low earth orbit Tracker, or WALT, antenna for communication with the small satellite.
The WALT antenna will track Kestrel Eye, also designed by the Tech Center and its industry partners, which is scheduled to be deployed from the International Space Station in late-October.
"The WALT antenna was designed and built completely in-house and will enable communications with the Kestrel Eye imaging satellite, a demonstrator for tactical space-based imagery, which can be proliferated in large numbers to form a constellation of satellites to provide persistent imaging capability to ground forces," said Walt Trammell, a USASMDC/ARSTRAT Tech Center engineer. "Engineers who participated in this effort gained insight into radio frequency design, development, trade-offs, simulation, fabrication, testing efforts and the hard labor of assembling it on the antenna platform in the Alabama summer heat.
"These activities build engineering experience, personal confidence, and character, which add to the science and technology strength of our command," he added.
When the idea of constructing the antenna was broached, Trammell said the challenge of designing, constructing, testing and building a project of this magnitude would be a major task, even for a large company, but he added the students and engineers working in the Tech Center's Concepts Analysis Laboratory were up to the challenge.
"We are all glad to finally be able to put the WALT to use and assist with the Kestrel Eye mission," said Mason Nixon, Tech Center Space Division general engineer. "We designed and built everything on the WALT. The structure, the electronics, the control system, the motor and power systems, and the antenna were all prototyped right here within the command.
"Additionally, some of the design requirements have had to be modified along the way. Consequently, it has taken about two years for the development of the antenna and associated software to be completed," he added.
Nixon said the WALT antenna uses what is called a perturbation model orbital propagator, similar to the SGP4 algorithm used by the Air Force, to determine Kestrel Eye's position at any given time. He said the propagator requires satellite position data, provided by the Air Force in the form of a two-line element, or TLE set.
From the TLE and propagator, Nixon said they can calculate the appropriate angles needed for tracking and use those angles to command the dish to point accurately at Kestrel Eye.
"The WALT antenna is the primary ground station antenna for tracking and communicating with Kestrel Eye at SMDC," Nixon said. "While our U.S. Pacific Command partners have their own antenna on Oahu, Hawaii, this will be our primary means of communication in Huntsville."
Kestrel Eye is a small, low-cost, visible-imagery satellite designed to provide images rapidly to the tactical-level ground Warfighter. Kestrel Eye is a microsatellite weighing approximately 50 kg with an electro-optical imaging telescope and camera capable of producing images with tactically useful resolution. Kestrel Eye will enhance situational awareness of Army brigade combat teams by providing satellite imagery without the need for conventional continental U.S.-based relays.
Currently 60 percent to 70 percent of Army systems depend upon space to perform their mission. Kestrel Eye is designed to be tactically responsive, with the ability to task the satellite and receive data from it during an overhead pass. It will provide a measure of satellite persistence that can provide situational awareness and images rapidly to the Warfighter.
"WALT is the primary ground station for Kestrel Eye operations and is operated remotely from the Redstone Satellite Operations Center via software designed by SMDC engineers," said Sgt. Austin R. Prosser, Redstone Satellite Operations Center operations noncommissioned officer in charge. "As of now, there are eight operators trained on the WALT and Kestrel Eye ground stations, and their primary mission with WALT is to track, communicate with, and command the satellite."
Prosser said he was originally introduced to WALT back in late 2015 when he was at SMDC to assist with the SMDC Nanosatellite, or SNaP Program.
"From a Soldier's point of view, WALT is an incredible development," Prosser said. "The hardware and software has been created in-house, which has allowed us to optimize our smallsat resources. Kestrel Eye will provide the Warfighter near real time imagery, which is no small feat. This capability will be demonstrated with Kestrel Eye."
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