0915 GMT (5:15 a.m. EDT)
Failure struck Russia’s troubled space program for the second time in three weeks Saturday, when a Proton rocket carrying a high-tech satellite for Mexico’s new $1.6 billion space-based communications network crashed shortly after liftoff.

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0650 GMT (2:50 a.m. EDT)
Here's what we know.

A Proton rocket launched from the Baikonur Cosmodrome in Kazakhstan at 0547 GMT (1:47 a.m. EDT) with Mexico's Centenario communications satellite, a spacecraft made by Boeing to establish a mobile communications network for Mexican national security agencies.

The rocket disappeared into clouds over the launch site moments after liftoff, but telemetry from the Proton indicated everything proceeded normally for the first few minutes of the flight.

The Russian space agency reports an anomaly occurred some time during the launch, but a Roscosmos statement offered no further information. Russian news agencies pointed to a failure in the rocket's third stage.

International Launch Services, the U.S.-based company managing the commercial launch, said engineers were having trouble receiving telemetry from the rocket, but an ILS official claimed tracking data showed the launcher flying normally.

0637 GMT (2:37 a.m. EDT)
Roscosmos has posted a statement on its website confirming a problem occurred during today's Proton launch, but the Russian space agency provided no details on the issue.
0628 GMT (2:28 a.m. EDT)
Interfax reports an emergency occurred 500 seconds into the flight during the Proton's third stage burn, adding debris could have impacted near the city of Chita in Siberia.
0620 GMT (2:20 a.m. EDT)
Russia's RIA Novosti news agency reports an "emergency situation" occurred during the launch sequence, and quotes a space industry source who says the Mexsat 1 satellite is likely to be lost.
0614 GMT (2:14 a.m. EDT)
If everything is going as planned, the Breeze M is now in a coast phase until ignition of the second upper stage burn at about 0654 GMT (2:54 a.m. EDT).

Separation of the Mexsat 1 satellite is scheduled after the Breeze M's fifth burn, at 1500 GMT (11 a.m. EDT).

0609 GMT (2:09 a.m. EDT)
The Breeze M and Mexsat 1 should now be in a circular parking orbit at an altitude of 173 kilometers, but ILS cannot confirm the outcome of the first Breeze M firing.

"We're definitely experiencing a telemetry problem getting data, but by other indications, in terms of tracking and NORAD data, it appears everything is progressing as it should be," says Russ Prytula, an ILS program director providing updates via the company's launch webcast.

"All indications are, with the available information, that things are proceeding nominally," Prytula says.

0607 GMT (2:07 a.m. EDT)
The first of five engine burns by the Breeze M upper stage in today's launch should be complete by now, but International Launch Services has provided few updates on the status of the flight.
0603 GMT (2:03 a.m. EDT)
ILS reports an "unusual situation" with issues receiving telemetry updates from the Proton rocket, but tracking of the launcher indicates all appears to be normal at this point in the flight.

The Breeze M upper stage should now be firing to boost the Mexsat 1 satellite into a preliminary low-altitude parking orbit.

0559 GMT (1:59 a.m. EDT)
We are awaiting updates on the progress of the Proton launch from International Launch Services.
0550 GMT (1:50 a.m. EDT)
T+plus 3 minutes, 30 seconds. The second stage's RD-0211 main engine and RD-0210 vernier engines continue firing at full power of 540,000 pounds of thrust.
0549 GMT (1:49 a.m. EDT)
T+plus 2 minutes, 25 seconds. Russian authorities confirmed the Proton's first stage has shut down and jettisoned, and the second stage engines are firing with a half-million pounds of thrust.
0548 GMT (1:48 a.m. EDT)
T+plus 70 seconds. The Proton rocket has passed the speed of sound and the phase of maximum aerodynamic pressure as it heads northeast from Baikonur.
0547 GMT (1:47 a.m. EDT)
Liftoff of the Proton rocket with Mexsat 1, a 5.9-ton communications satellite to establish a mobile communications network for Mexico.
0546 GMT (1:46 a.m. EDT)
T-minus 60 seconds minutes. The ignition sequence for the six first stage RD-276 engines begins at T-minus 2.5 seconds, reaching a 40 percent thrust level at T-minus 1.75 seconds and 100 percent thrust at T-minus 0.9 seconds.
0545 GMT (1:45 a.m. EDT)
T-minus 2 minutes. The countdown is being run by a master computer sequencer.
0542 GMT (1:42 a.m. EDT)
T-minus 5 minutes. Mexsat 1 marks the first satellite owned by the Mexican government to launch on an International Launch Services Proton rocket. It also marks the 12th satellite built by Boeing Satellite Systems to launch on an ILS Proton.
0539 GMT (1:39 a.m. EDT)
T-minus 8 minutes. The readiness of the Proton core vehicle, the Breeze M upper stage and Mexsat 1 will be verified over the next few minutes.
0538 GMT (1:38 a.m. EDT)
T-minus 9 minutes. The Proton launcher on the pad weighs about 1.5 million pounds, and it will be powered into the sky by six first stage RD-276 engines producing more than 2 million pounds of thrust. It will turn to the northeast on an initial launch azimuth of 61.3 degrees.

The Mexsat 1 satellite weighs about 5,325 kilograms, or 11,739 pounds, at liftoff. Mexsat 1 was transitioned to internal power a few minutes ago.

0537 GMT (1:37 a.m. EDT)
Liftoff of the Proton rocket is 10 minutes away. This will be the:
0536 GMT (1:36 a.m. EDT)
T-minus 11 minutes. The final launch pad workers are evacuating to a safe distance away from the rocket.
0532 GMT (1:32 a.m. EDT)
With 15 minutes left in the countdown, everything remains on schedule for launch at 0547 GMT (1:47 a.m. EDT; 11:47 a.m. Baikonur time). It will take more than nine hours to deploy Mexsat 1 in the proper orbit.

The Proton rocket's first stage will blast off powered by six RD-276 engines producing more than 2 million pounds of thrust. The 191-foot-tall launcher will ascend northeast from Baikonur, dropping its first stage 2 minutes after liftoff, giving way to the Proton's second stage RD-0211 main engine for a three-and-a-half minute burn.

The Proton's third stage, using a RD-0213 main engine with 131,000 pounds of thrust, next will fire for about four minutes. Separation of the 13.1-foot-diameter nose cone occurs during the third stage burn at T+plus 5 minutes, 47 seconds.

The Breeze M upper stage will assume control at T+plus 9 minutes, 42 seconds, when it separates from the Proton's third stage. Five Breeze M engine burns are planned over a nine-hour period to inject the 11,739-pound Mexsat 1 spacecraft in the proper geosynchronous transfer orbit with a low point of 5,583 miles (8,985 kilometers), a high point of 22,236 miles (35,786 kilometers) and an inclination of 20.1 degrees.

FRIDAY, MAY 15, 2015
2320 GMT (7:20 p.m. EDT)
Russian officials have given approval to fuel the Proton rocket for liftoff at the Baikonur Cosmodrome in Kazakhstan at 0547 GMT (1:47 a.m. EDT).

The Breeze M upper stage has already been filled with its hypergolic propellant mixture, and the three-stage Proton booster will be fueled with liquid hydrazine and nitrogen tetroxide in the next few hours.

The 191-foot-tall Proton M rocket rolled to the launch pad at Baikonur on May 14, riding a railroad car before it was lifted upright on the launch mount. A mobile gantry with access platforms for workers was then installed around the rocket.

The Mexsat 1, or Centenario, satellite owned by the Mexican government is shrouded in the nose cone of the Proton rocket.

Built by Boeing Satellite Systems, the 11,739-pound spacecraft will be positioned in geostationary orbit over the Pacific Ocean to broadcast voice and data services to Mexican security authorities on land, at sea, and in the air to support national security, civil and humanitarian efforts.