Spaceflight Now: Atlas launch report


June 30, 2000 -- Follow the countdown and launch of NASA's TDRS-H communications satellite aboard a Lockheed Martin Atlas 2A rocket. Reload this page for the very latest on the mission.

1138 GMT (7:38 a.m. EDT)

Now one hour away from the scheduled launch of AC-139 with the TDRS-H communications relay satellite for NASA from Cape Canaveral Air Force Station in Florida.

At pad 36A Centaur liquid hydrogen tanking is underway. This is the third and final step in fueling the Atlas rocket and Centaur upper stage for launch this morning. Also, the pogo suppression system at the pad has been readied. The system will be used to dampen the "bounce" of the rocket during engine ignition.

1135 GMT (7:35 a.m. EDT)

The gaseous nitrogen pressurization problem has been resolved and the troubleshooting team sent to Complex 36 is leaving the area. This allows for fueling of the Centaur upper stage with liquid hydrogen to now begin.

1130 GMT (7:30 a.m. EDT)

The Atlas liquid oxygen tank has been filled to 98 percent and topping to flight level is starting.

The Air Liquide team at Complex 36 is working to fix a pressure regulator problem. There is no estimate how long this will take. Once the workers clear the area, liquid hydrogen fueling can start for the Centaur upper stage.

Meanwhile the Range has found some boats off shore from Cape Canaveral. Officials say the boats should be clear of the restricted area in time for the Atlas to launch on schedule at 8:38 a.m. EDT (1238 GMT) today. Boats have been a hot topic at Cape Canaveral recently after causing multiple delays in last month's launch of the first Atlas 3 rocket.

1118 GMT (7:18 a.m. EDT)

The liquid hydrogen chilldown is now complete. However, loading of the super-cold fuel into the rocket's Centaur upper stage is being delayed while workers are deployed at Complex 36 to examine a gaseous nitrogen pressurization problem. In addition, the self test of the rocket's flight termination system scheduled at this point in the countdown is being pushed back for safety sake.

Although the countdown timeline is being held up, there is a 45-minute built-in hold upcoming at T-minus 5 minutes. This time will allow the launch team to catch up in preparation for the scheduled 8:38 a.m. EDT (1238 GMT) liftoff this morning.

1108 GMT (7:08 a.m. EDT)

T-minus 45 minutes and counting. Now 90 minutes away from this morning's planned launch of a Lockheed Martin Atlas 2A rocket with NASA's Tracking and Data Relay Satellite-H. Countdown clocks will continue to T-minus 5 minutes where a 45-minute planned hold will occur.

At launch pad 36A the Centaur upper stage liquid oxygen tank is nearly completely full and the Atlas booster stage liquid oxygen tank is 40 percent full as fueling operations continue. Liquid hydrogen tanking for Centaur is upcoming shortly as soon as a team of workers departs the Complex 36 area.

The team from subcontractor Air Liquide was dispatched a little earlier this morning to investigate a gaseous nitrogen pressure loss at the pad.

Otherwise there are no additional problems to report. Weather conditions are currently beautifu this morning, but meteorologists are keeping a close eye on thunderstorms to the northwest of Cape Canaveral.

1103 GMT (7:03 a.m. EDT)

The liquid oxygen tank inside the Atlas booster stage is now at 10 percent. The rocket's shiny exterior is now turning a frosty white as a thin layer of ice forms from the super-cold liquid oxygen.

Meanwhile Centaur liquid oxygen topping to flight level has started. As the countdown proceeds, the tank will be replenished to replace the cryogenic liquid oxygen that naturally boils away.

1057 GMT (6:57 a.m. EDT)

After safety discussions by the Anomaly Team, approval has been given to start the chilldown conditioning of liquid hydrogen propellant feed lines at pad 36A. There is a team of workers heading into Complex 36 to investigate a pressurization problem, but their safety won't be threatened by preparing the liquid hydrogen system for fueling, officials concluded. However, hydrogen loading into the rocket will not start until after the crew leaves the area.

The chilldown sequence is done to thermally prepare the plumbing before the super-cold cryogenic flows through the pipes and into the rocket. Also at this time, the Complex 36 Blockhouse doors are being sealed.

For now liftoff remains scheduled for 8:38 a.m. EDT (1238 GMT).

1054 GMT (6:54 a.m. EDT)

The Centaur liquid oxygen tank has reached 95 percent full level where it is being maintained. Topping to 100 percent will be completed later. And now loading of liquid oxygen into the Atlas booster stage is beginning.

1049 GMT (6:49 a.m. EDT)

The final alignment of the Atlas rocket's inertial navigation guidance computer has been completed, and the flight control system final preps are now beginning. The Centaur liquid oxygen tank is now 80 percent loaded.

Launch of the Atlas 2A vehicle with NASA's TDRS-H satellite remains scheduled for 8:38 a.m. EDT this morning.

1045 GMT (6:45 a.m. EDT)

A team of subcontractor personnel is headed to Complex 36 to examine a pressurization problem, which is affecting the gaseous nitrogen system. The workers will access the pressure regulator station near the parking lot outside pad 36B. Meanwhile, officials are discussing whether is safe to begin liquid hydrogen system chilldown with people so close to the Atlas rocket atop pad 36A.

1037 GMT (6:37 a.m. EDT)

The Centaur liquid oxygen tank has been filled above 20 percent.

1026 GMT (6:26 a.m. EDT)

Chilldown condition of the liquid oxygen transfer lines at pad 36A has been completed and the launch team is now beginning to fill the Centaur upper stage with its its supply of liquid oxygen for launch today at 8:38 a.m. EDT.

1014 GMT (6:14 a.m. EDT)

The sun is beginning to rise here in Central Florida along the edge of the Atlantic Ocean. Launch of the Atlas rocket remains scheduled for 8:38 a.m. EDT (1238 GMT) from Cape Canaveral.

The "chilldown" procedure has started to thermally condition the liquid oxygen propellants lines at pad 36A in advance of loading the Centaur upper stage. Chilldown is a process in which a small amount of the super-cold liquid oxygen is released from the pad's storage tank into the feed lines that lead to the rocket.

Meanwhile, the latest steering program is being loaded into the rocket's guidance computer based upon the upper level wind conditions. Also, the wind damper arm connecting the Atlas 2A rocket with the launch tower is being completed.

1008 GMT (6:08 a.m. EDT)

T-minus 105 minutes and counting. Again the decision has been made to delete the planned 30-minute hold at this point in the countdown. The time will be added to the planned 15-minute hold at T-minus 5 minutes, producing a hold duration of 45 minutes.

With the countdown timeline being accelerated by a half-hour this morning, a poll of the launch team by Launch Conductor John Martin was just completed and all parties were go to begin loading super-cold cryogenics aboard the Atlas/Centaur vehicle later this hour.

Meanwhile, the mobile service tower has been retracted and technicians are now securing the structure for launch. Road blocks are being set up at Complex 36 while technicians at pad 36A are beginning test stand checks. The launch pad crew is now departing the complex in preparation for fueling operations.

Also, a test of the C-band beacon system has been underway. This system is used by the Eastern Range to track the rocket during flight.

1001 GMT (6:01 a.m. EDT)

In advance of fueling the Atlas rocket this morning, Air Force Launch Weather Officer Jim Sardonia just gave another update to officials. He reports that the thunderstorms to the northwest of Cape Canaveral are not expected to move into the area until after the close of today's launch window. However, the upper level winds are strong enough that the thunderstorm cloud tops -- anvil clouds -- could move into the Cape region in about two hours. The forecast is still 70 percent "go" for launch but the anvil cloud and thick cloud rules will be watched very closely.

0949 GMT (5:49 a.m. EDT)

Officials have just decided to revise the countdown plan today, approving an option to remove the scheduled 30-minute built-in hold at T-minus 105 minutes, which would have started at 6:08 a.m. EDT. That half-hour will now be added to the already-scheduled 15-minute hold at the T-minus 5 minute mark. This will be done to give a 45-minute period to work any problems very late in the countdown given today's relatively short 40-minute launch window.

0938 GMT (5:38 a.m. EDT)

Retraction of the mobile service tower from around the Atlas 2A rocket is starting at Cape Canaveral's launch pad 36A. The tower will be fully retracted to the "maintenance area" for launch.

The launch team reported preps for the Atlas and Centaur propulsion systems are complete, as were the hydraulic preps for Atlas. Also the rocket's Inertial Navigation Unit guidance computer has completed its navigation test and final alignment for launch has started.

One other note on the weather, so far upper level wind conditions are favorable this morning. Weather balloons released over the last few hours have found consistent winds with no significant shears. The maximum winds at 40 knots at 45,000 feet.

0923 GMT (5:23 a.m. EDT)

T-minus 150 minutes and counting. Man statiosn for Integrated Launch Operations. The entire launch team is now reporting on station at Cape Canaveral's Complex 36 for the liftoff of an Atlas 2A rocket at 8:38 a.m. EDT (1238 GMT).

Countdown clocks will pause twice over the next three hours and 15 minutes in advance of launch. Built-in holds are planned at T-minus 105 for 30 minutes and at T-minus 5 minutes for 15 minutes.

At launch pad 36A, access platforms and equipment inside the mobile service tower have been stowed, and technicians are preparing to retracted the structure from around the rocket in about 15 minutes.

Over the past hour or so, the liquid oxygen and liquid hydrogen system checkouts were completed and now the final system preps have started. The purges to the Centaur upper stage began and were configured on low-flow. Also the Blockhouse clocks were switched from local time to sequencer countdown and verified to be displaying the correct T-minus time. Meanwhile, Range Safety conducted a holdfire test to ensure it could stop the launch moments before liftoff if necessary.

The latest weather forecast continues to show a 70 percent chance of acceptable conditions today. Air Force Launch Weather Officer Jim Sardonia just briefed management and reported that the stationary cold front in North Florida has produced a thunderstorm west of Gainsville. That thunderstorm is moving toward the southeast -- toward Cape Canaveral -- and will be located northwest of pad 36A at the opening of today's launch window. Although this particular thunderstorm is not expected to be a problem there is concern any additional cells that develop closer to the Cape could be a factor. Sardonia says he believes conditions will be better in the first part of today's 40-minute window than in the later part.

0700 GMT (3:00 a.m. EDT)

The countdown is well underway this morning at Cape Canaveral's Complex 36 as the Lockheed Martin launch team readies an Atlas 2A rocket for liftoff at 8:38 a.m. EDT (1238 GMT) with NASA's TDRS-H communications satellite aboard.

At pad 36A over the past little while internal power tests of the Atlas and Centaur stages were completed, the navigation test of the rocket's Inertial Navigation Unit guidance computer was started and checks were beginning on the Centaur main engine ignitors. Also at the Cape, the first weather balloons were being released to gather data on high altitude conditions.

0240 GMT (10:40 p.m. EDT)

Lockheed Martin is less than 10 hours away from Friday morning's scheduled launch of an Atlas 2A rocket with NASA's Tracking and Data Relay Satellite-H. Activities are reported to be on track for liftoff at 8:38 a.m. EDT (1238 GMT), the opening of a 40-minute window.

The technical members of the launch team will begin arriving on console at Cape Canaveral Air Force Station's Complex 36 in about 90 minutes to begin final pre-flight preparations.

Countdown clocks will start ticking at 12:48 a.m. EDT (0438 GMT), and the rocket is scheduled to be powered up for launch at 2:08 a.m. EDT (0608 GMT). Senior managers will report for duty at 4:30 a.m. EDT (0830 GMT) at the Mission Directors Center in Cape Canaveral's Industrial Area. The full launch team shall be seated in the Complex 36 Blockhouse by 5:23 a.m. EDT (0923 GMT) as the Integrated Launch Operations begin from T-minus 150 minutes and counting.

The mobile service tower enclosing the Atlas rocket at pad 36A will be retracted for launch at 5:38 a.m. EDT (0938 GMT), pending acceptable weather conditions. After a 30-minute long built-in hold at T-minus 105 minutes, the three-step process of fueling the rocket should start. Loading of super-cold liquid oxygen into the Centaur upper stage will be first at 6:52 a.m. EDT (1052 GMT). Next will be liquid oxygen tanking of the Atlas booster stage beginning at 7:18 a.m. EDT (1118 GMT), followed by liquid hydrogen fueling of the Centaur starting at 7:32 a.m. EDT (1132 GMT).

A 15-minute planned hold will occur at 8:18 a.m. EDT (1218 GMT) as the countdown reaches T-minus 5 minutes. During the pause, final readiness polls of launch team members and management will be conducted. If no problems are reported, clocks will resume ticking at 8:33 a.m. EDT (1233 GMT) for liftoff at 8:38 a.m. EDT (1238 GMT).

The two-and-a-half stage Atlas rocket, known as AC-139, will need just shy of 30 minutes to inject the TDRS-H satellite into a highly elliptical geosynchronous transfer orbit around Earth.

The Atlas booster stage will complete its job in the first 4 1/2 minutes and then drop away. The powerful Centaur upper stage will take over, firing for just under five minutes to achieve a parking orbit with an approximate apogee of 312 nautical miles, perigee of 90 nautical miles and inclination of 28.3 degrees. After a 15-minute long coast through space, the Centaur's twin engines will reignite for a short 80-second firing to accelerate and boost the TDRS satellite.

At T+plus 29 minutes and 55 seconds, the spacecraft should be released into a deployment orbit with an approximate high point of 16,240 nautical miles, low point of 120 miles and inclination of 27.0 degrees.

Over the coming two weeks, the kick engine on the TDRS-H spacecraft will be fired repeatedly to propel the satellite into a circular geostationary orbit 22,300 miles above the equator. The craft will be parked at 150 degrees West longitude for testing and checkout. Its final perch is slated to be 171 degrees West as part of NASA's TDRS constellation.

1500 GMT (11 a.m. EDT)

Senior managers this morning cleared the Atlas 2A rocket for flight tomorrow after putting to rest concerns with its upper stage engines. "Everybody is go for launch," ILS spokeswoman Julie Andrews said from Cape Canaveral.

The Lockheed Martin-built rocket is poised to carry NASA's Tracking and Data Relay Satellite-H into Earth orbit. Manufactured by Hughes, the satellite is the first of a new generation for NASA's fleet of orbiting tracking stations-in-the-sky. The TDRS system is used to return data, television, voice and science information from a host of manned and robotic space missions including the space shuttle and Hubble Space Telescope. In addition, classified spy satellites also use TDRS services.

NASA currently has six aging TDRS satellites in space. TDRS-H and its sister-craft TDRS-I and -J to be launched in 2002 and 2003 will replenish the constellation to provide a communications relay framework well into the next decade.

Friday's available launch window extends from 8:38 to 9:18 a.m. EDT (1238-1318 GMT).

The weather forecast remains unchanged with a 70 percent chance of acceptable conditions.


With last-minute engine checks completed, officials will convene a 9 a.m. EDT review meeting on Thursday to determine if a Lockheed Martin Atlas rocket can be cleared for launch on Friday to haul a NASA communications relay satellite into space. Liftoff is scheduled for 8:38 a.m. EDT (1238 GMT) from pad 36A at Cape Canaveral Air Force Station in Florida.

The launch of the Tracking and Data Relay Satellite-H, or TDRS-H, was pushed back 24 hours to Friday after a flight constraint against the Centaur upper stage's twin RL-10A-4-1 engines was issued by manufacturer Pratt & Whitney.

The trouble stems from an April test firing of an RL-10B2 engine, a newer version of the liquid-fueled powerplant used by the upper stages of Boeing Delta 3 rockets. During the engine's production hot-firing, an internal thrust control valve failed to open. The malfunction caused a thrust overshoot, the engine aborted the test and was shut down.

While the Atlas and Delta versions of the RL-10 have differences, they are both based upon a common design and use many of the same parts, including the thrust control valve.

Initial analysis suggested moisture in the valve caused the failure. The conclusion allowed the RL-10 to be cleared for use aboard two Atlas rocket launches in May -- an Atlas 2A with the GOES-L weather satellite and the first Atlas 3A rocket. Both launches were successful.

However, more recent bench testing of the valve after it was dried showed the piston-like device still failed to open, prompting investigators to pursue other explanations for the problem. A new theory says a leaky bypass seal could have caused the stuck valve.

In order to ensure the two RL-10 engines aboard the Atlas launcher at pad 36A have good seals, leak checks were performed Tuesday night. Data reviews were ongoing Wednesday in advance of the senior-level meeting Thursday morning. But all indications showed the seals to be leak-free, and Pratt & Whitney was fully expecting to clear the engines for launch.

Pratt & Whitney spokesman Patrick Louden said the company has extensive, successful flight experience with the thrust control valve. But had added that officials needed to be completely sure the problem seen in the factory would not threaten the success of the upcoming TDRS launch.

Provided the flight constraint is lifted in the morning, preparations are on schedule for starting the launch countdown at 12:48 a.m. EDT (0448 GMT) on Friday. The available launch window will extend from 8:38 to 9:18 a.m. EDT (1238-1318 GMT), a duration of 40 minutes. A backup launch opportunity on the Eastern Range is possible on Saturday, if needed.

The weather forecast for Friday is slightly less optimistic than earlier, but there is still a 70 percent chance of acceptable conditions. The worsening forecast is due to an approaching frontal system that is expected to slowly drift into north Florida on Friday morning. The closer the system gets to Cape Canaveral, the more unstable the atmosphere will become, Launch Weather Officer Jim Sardonia said today. During the launch window there is the threat of cumulus clouds within 10 nautical miles of the launch pad, which is a constraint. Also of concern will be thunderstorm cloud tops, called anvil clouds, and thick cloud layers drifting towards the Cape from thunderstorms predicted to the northwest.

The actual launch time forecast calls for scattered cumulus clouds at 3,000 feet with 3/8ths sky coverage, altostratus clouds broken at 10,000 feet with 5/8ths sky coverage and broken cirrus clouds with 6/8ths sky coverage at 25,000 feet, visibility of 7 miles, southwesterly winds 10 gusting to 18 knots at pad 36A, a temperature of 78 to 80 degrees F, relative humidity of 85 percent and isolated rainshowers to the northwest.

Should the launch be delayed to Saturday, the weather forecast calls for a 60 percent chance of acceptable conditions. The concerns will be nearby rainshowers and the chance of thick layered clouds and anvil clouds.

Spaceflight Now will provide extensive live coverage during the final hours of the countdown and the 30-minute long flight of the Atlas rocket to launch the TDRS-H satellite. We will have a running play-by-play of the events on this page and offer a live QuickTime streaming video broadcast of the launch starting at 7 a.m. EDT (1100 GMT).

TUESDAY, JUNE 27, 2000
2220 GMT (6:20 p.m. EDT)

The launch of a NASA tracking and communications relay satellite this week aboard a Lockheed Martin Atlas 2A rocket will be delayed one day to Friday so technicians can double check engines on the Centaur upper stage.

Officials made the decision late this afternoon in the wake of a valve problem encountered recently at engine-maker Pratt & Whitney. A thrust control valve malfunction caused an RL-10 engine to shut down during a test firing at the factory, International Launch Services spokeswoman Julie Andrews said.

The Atlas rocket's Centaur upper stage carries two RL-10 engines that will be used to propel the TDRS-H satellite into its planned geosynchronous transfer orbit on Friday morning.

Testing has been ordered to ensure the engines on the rocket at launch pad 36A are free of problems, Andrews said. The ongoing work forced the liftoff to be delayed 24 hours. Friday's launch window extends from 8:38 to 9:18 a.m. EDT (1238-1318 GMT).

The weather forecast for Friday shows a 90 percent chance of good conditions. The only concerns will be cumulus clouds moving too close to the launch pad and a slight chance of coastal rainshowers.

MONDAY, JUNE 26, 2000

NASA plans to launch the first spacecraft in a new generation of tracking and data relay satellites on Thursday morning aboard a Lockheed Martin Atlas 2A rocket from Cape Canaveral.

Liftoff from pad 36A is scheduled for 8:38 a.m. EDT (1238 GMT), the opening of a 40-minute launch window extending to 9:18 a.m. EDT (1318 GMT). It will take the rocket 29 minutes and 55 seconds to deliver the 7,011-pound satellite into the intended geosynchronous transfer orbit.

The early weather forecast shows generally favorable conditions for launch. Air Force Launch Weather Officer Jim Sardonia gave this report Sunday morning:

"On launch day, southerly winds are expected which may produce a few isolated coastal rainshowers, however these cells will be very small and short-lived. The only concern on launch day at this time includes the slight chance of enhanced cumulus clouds and isolated coastal rainshowers within 5 nautical miles of SLC 36."

The launch time forecast calls for scattered cumulus clouds at 3,000 feet with 3/8ths sky coverage, visibility of 7 miles, south-southwesterly winds 8 to 12 knots at the pad, a temperature of 76 to 78 degrees F, relative humidity of 75 percent. Overall there will be a 90 percent chance of meeting the launch weather rules.

Should the launch be delayed until Friday morning for some reason, similar weather is predicted with a 90 percent chance of acceptable conditions.

Built by Hughes Space and Communications and based upon the highly successful HS-601 satellite design, the TDRS-H spacecraft will join NASA's orbiting communications network.

Started in 1983, the TDRS System is used to return voice, data, science information and television from space shuttle missions and a variety of unmanned satellites to Earth. TDRSS also provides tracking of other satellites in orbit. In the future, TDRSS will be extensively by the International Space Station.

TDRS-H is the first of three new satellites in a replenishment effort to keep the system operating through the next decade and beyond. TDRS-H, I and J also feature Ka-band capability, which increases the data throughput threefold.

The previous TDRS satellites were built by TRW and launched aboard space shuttle missions STS-6, 51L, 26, 29, 43, 54 and 70. TDRS-B was lost in the shuttle Challenger accident on STS-51L in 1986.

Today all six TDRS craft in orbit 22,300 miles above Earth are still functioning, although some have degraded systems.

The Atlas booster stage and Centaur upper stage were erected on pad 36A during the week of May 22. The satellite was transported from its preparation facility at Kennedy Space Center to the launch pad on June 17. Officials completed the Flight Readiness Review on Thursday, clearing the way for pre-launch work to continue.

This will be the fifth Atlas launch of 2000 and 18th overall for the Atlas 2A rocket, all of which have been successful.

Live webcast
Spaceflight Now is providing a live QuickTime streaming broadcast of today's launch of the Lockheed Martin Atlas 2A rocket from Cape Canaveral. Coverage is currently underway.

Next launch
Vehicle: Atlas 2A (AC-139)
Payload: NASA's TDRS-H
Launch date: June 30, 2000
Launch window: 1238-1318 GMT (8:38-9:18 a.m. EDT)
Launch site: SLC-36A, Cape Canaveral, Fla.

Flight profile
Track the major launch events for the Atlas 2A rocket carrying the TDRS-H satellite on Spaceflight Now's interactive flight profile page (requires JavaScript).

Pre-launch briefing
Launch timeline - Chart with times and descriptions of events to occur during the launch.

Atlas 2A vehicle data - Overview of the rocket that will launch TDRS-H into space.

TDRS-H - Description of the satellite to be launched on AC-139.

History of TDRSS - Past launches of TDRS satellites and their current status.

Launch windows - Available windows for possible future launch dates of AC-139.

Launch danger zone - Map shows restricted safety area off Cape Canaveral for this launch.

Video vault
Watch a movie about the planned sequence of events as the Atlas 2A rocket carries the TDRS-H communications satellite into orbit.
  PLAY (789k, 1min 51sec QuickTime file)
Animation shows NASA's Tracking and Data Relay Satellite-H working in geostationary orbit above Earth.
  PLAY (285k, 24sec QuickTime file)
Satellite builder Hughes tests the 15-foot diameter graphite shaped springback reflector antennas on TDRS-H.
  PLAY (169k, 12sec QuickTime file)
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Inside the blockhouse

Step inside the historic Complex 36 Blockhouse where the 120 members of the launch team control every countdown and liftoff of Atlas rockets from Cape Canaveral.
  VIEW (286k QuickTime file)
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