The Ariane 4 rocket lifts off Tuesday from the ELA-2 launch pad with Galaxy 4R onboard. Photo: Arianespace TV

Europe's Ariane 4 rocket placed a U.S. communications satellite into orbit Tuesday night but Arianespace's jungle launch pads will become silent until at least mid-summer due to spacecraft engine troubles.

Arianespace Flight 129 roared into the evening sky in South America right on time at 8:29 p.m. EDT Tuesday (0029 GMT Wednesday), beginning a 21-minute flight across the Atlantic Ocean and into Earth orbit with PanAmSat's Galaxy 4R spacecraft.

Tracking cameras followed the three-stage Ariane 42L rocket during the first 2 1/2 minutes of flight and showed the twin liquid-fueled strap-on boosters separating after they finished firing.

No problems were reported during the launch -- the third Ariane 4 of the year -- and Galaxy 4R was released from the rocket as it flew just west of the Central African coastline.

See the Mission Status Center for our play-by-play description of the countdown and launch.

Hughes Space and Communications, builder of the Galaxy 4R satellite, quickly established contact with the spacecraft at 9:06 p.m. EDT (0106 GMT) via the Daan Magot tracking station in Indonesia. Initial checks of the satellite indicated Galaxy 4R was healthy following its venture into space.

Over the next week, the satellite's liquid-propellant onboard kick motor will be fired to raise its altitude from the highly elliptical geosynchronous transfer orbit achieved by Ariane to the final geostationary orbit.

The Ariane 4 rocket placed Galaxy 4 into an orbit swinging from 125 to 20,115 miles, according to Arianespace data. The final circular orbit will be 22,300 miles above the Equator, parking the craft at 99 degrees West longitude.

The rocket's nose cone is about to enclose the Galaxy 4R satellite during pre-launch processing earlier this month in Kourou. Photo: Arianespace.com

After the orbit raising maneuvers, the satellite's two solar arrays will be deployed to recharge onboard batteries and the communications reflectors will be unfurled.

A month-long testing period is planned from late-April to late-May, checking the Galaxy 4R's onboard systems before control is handed from Hughes to PanAmSat for commercial service starting in early June.

Galaxy 4R built to serve North America
From its orbital perch, Galaxy 4R will be aimed at North America to relay television, radio and data transmissions and provide Internet connection to users in the continental United States, Alaska, Hawaii and Puerto Rico.

Customers already signed up to use Galaxy 4R include the Encore movie channel, National Public Radio, NHK, Televisa, PageNet paging service and AT&T's "Headend in the Sky" digital cable service and America Online's AOL Plus via DirecPC.

Galaxy 4R is the third new satellite PanAmSat has launched since December and four more are planned through mid-2001. PanAmSat ordered Galaxy 4R to replace its namesake, which malfunctioned in space in 1998.

Once Galaxy 4R enters service, PanAmSat will move its Galaxy 6, 7 and 11 satellites to different orbital slots, all of which will allow the company to expand its services to North America. PanAmSat will have 21 operational satellites, including 11 serving North America.

A bond between companies
For PanAmSat and Arianespace executives, Tuesday night's launch was a thrilling success.

"This has been a wonderful day," said Doug Kahn, president and CEO of PanAmSat. "I want to thank everyone at Arianespace for an outstanding liftoff."

The twin liquid-propellant strap-on boosters separate from the Ariane 4 rocket Tuesday night. Photo: Arianespace TV

"The relationship between Arianespace and PanAmSat is a long love story," said Jacques Rossignol, chief operating officer of Arianespace. "PanAmSat used the first Ariane 4 in 1988, which means in 12 years we have launched 16 PanAmSat satellites."

Kahn joked about the clear skies over Kourou during the launch, which was in stark contrast to the record rainfall experienced over the last week.

"I knew we would have a good launch. I didn't know Arianespace could also control the weather. So we are please you made for no rain and a wonderful evening so everyone could see the wonderful launch tonight," Kahn said.

Next Ariane launch date anyone's guess
During post-flight celebratory speeches, Arianespace typically announces plans for its next launch. But that was not the case Tuesday night because the company's near-term launch schedule has been thrown into disarray by engine troubles plaguing several European-built satellites slated for launches in the coming months.

"It is not possible for us today to set a clear date to resume our flights," Rossignol said. "We don't even know whether we will launch an Ariane 4 or an Ariane 5."

At the center of the trouble is a small German-made thruster that is used on satellites for orienting and station-keeping. Officials say anomalies have been found in a batch of the thrusters that are installed on several spacecraft. Satellite builders, as a result, have delayed delivering the craft until the issue is resolved.

The mobile service gantry is rolled back from the Ariane 4 rocket Tuesday afternoon in preparation for the final hours of the countdown. Photo: Arianespace TV

"We at Arianespace are ready to receive the satellites," Rossignol said. "If the plans we have are accurate and true, then we will resume our flights by the end of June or beginning of July, that is all I can say today, unfortunately."

Arianespace has already launched four times this year -- three Ariane 4s and one Ariane 5 rocket. It intends to launch a total of five Ariane 5s and seven or eight Ariane 4s in 2000.

The halt in flights is nothing new to Arianespace, which continues to dominate the lucrative commercial satellite launch market.

"This type of stop in flights has already occurred in the past. It occurred last year and the year before and the interruptions were longer. I think now we are quite used to this. We have hiccups like this but we are very flexible," said Rossignol.

Arianespace was able to complete eight successful launches in a fast-paced period between August and December last year.

"Our operational teams are up to the challenge of reacting quickly when payloads are ready for launch, and they are backed up by European industry which is maintaining the Ariane manufacturing rate," said Jean-Charles Vincent, the director of Arianespace's office at the Kourou spaceport.