Atlas 5 rocket boosts Navy communications satellite into space
In a spectacular dawn climb to space, a United Launch Alliance Atlas 5 rocket boosted a high-power Navy communications satellite into orbit Wednesday, the fourth of five planned relay stations providing high-speed smartphone-like capabilities to troops around the world.
Running two days late because of concerns about then-Tropical Storm Erika, the Atlas 5's Russian-built RD-180 first stage engine roared to life at 6:18 a.m. EDT (GMT-4) followed by ignition of five solid-fuel strap-on boosters that quickly pushed the rocket away from pad 41 at the Cape Canaveral Air Force Station.
Liftoff was delayed 19 minutes because of problems with a gaseous nitrogen supply, but the remainder of the countdown proceeded smoothly to launch, and after briefly climbing straight up on 2.5 million pounds of thrust, the 206-foot-tall rocket arced over onto an easterly trajectory and accelerated toward space.
The strap-on boosters burned out and fell away about one minute and 50 seconds after liftoff. Then, climbing into sunlight, the rocket put on a jaw-dropping sky show with an expanding, brilliant white exhaust plume briefly visible that looked like a giant comet streaking toward the horizon.
The RD-180 fired for four minutes and 24 seconds before it shut down as planned and the first stage fell away. A hydrogen-burning Aerojet Rocketdyne RL10C-1 engine in the rocket's Centaur second stage then fired up to continue the climb to orbit.
The second-stage engine shut down a little more than 12 minutes after launch, putting the vehicle into a preliminary orbit. Two additional second-stage firings were needed to put the payload into the required elliptical "geostationary transfer" orbit with a low point of some 2,370 miles and a high point of around 22,236 miles.
The Navy's fourth Mobile User Objective System (MUOS) satellite was expected to be released from the Centaur stage about two hours and 54 minutes after launch.
If all goes well, the satellite's on-board propulsion system will be used over the next nine days or so to raise the low point, or perigee, of the orbit, putting MUOS-4 into a circular orbit 22,300 miles above the equator. At that geosynchronous altitude, satellites take 24 hours to complete one orbit and thus appear stationary in the sky.
Flight controllers then will oversee deployment of the satellite's solar arrays and two main antennas. A 17-foot-wide gold mesh dish will send and receive signals from ground terminals that currently send voice and data through older Ultra High Frequency Follow-On, or UHF, satellites.
A much larger 46-foot-side antenna will provide the equivalent of 3G-class cellular network-type communications.
"MUOS will provide crystal-clear voice communications where the users on a line will be able to recognize each other's voices," Iris Bombelyn, a Lockheed Martin vice president, told reporters in a pre-launch conference call. "It is better than your cell phone and ... this is very important for our war fighters."
The newest MUOS satellite will provide "beyond-line-of-sight communications" with "smartphone-like features," she said, so "our mobile forces will not only be able to talk, they'll be able to use those simultaneously with text, exchange videos, transfer mission data or do conference calls. And we have a prioritization system so the most urgent message will get through."
Built by Lockheed Martin, MUOS-4 will complete the core of an operational network with a fifth spacecraft, scheduled for launch next year, serving as an orbital spare. The new satellites eventually will replace the Navy's older UHF comsats.
"We're looking forward to ... completing the Navy's initial constellation of four satellites in orbit," Bombelyn said. "With all ground stations now in place, the MUOS network will have near-global coverage allowing mobile forces to communicate from almost anywhere in the world."
