The request for proposals, issued last week, calls for "commercial services to launch and support its Tracking Phenomenology Experiment [TPE],"and represents the first step toward a system to defend against hypersonic missiles.

The package is the first part of SDA's plans to deploy a constellation of low orbiting satellites to guard against hypersonic weapons, ballistic missiles capable of traveling five times the speed of sound, Space News reported.

The United States is developing it's own hypersonic weapons through the Prompt Global Strike program, and it is believed that Russia and China have embarked on similar development programs as well.

The proposed defense system relies on sensors that can accurately recognize missile signals. The system is expected to start with at least three satellites, and eventually grow to include five more.

Data will be collected "so that we can really justify that we've chosen the correct bands, that we understand some of the phenomenology," SDA Director Derek Tournear said last week on a webcast.

The proposal's requirements include pitches for program management, spacecraft bus fabrication, satellite integration, mission integration, shipment of satellite to launch site, launch site support, ground and flight system safety, satellite bus and OPIR [Overhead Persistent Infrared] payload data delivery, and performance assurance.

By 2022 or 2023, a missile warning network with about 70 satellites is planned, according to the request for propals.

"That will give us enough coverage in low earth orbit so that we can have essentially regional persistence," said Tournear. "We'll have to determine which areas of the globe we want to focus on. That's the first time we'll have enough satellites up there to where we could actually fight a war with those satellites."