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Archive for November, 2004

20-Nov-04 | Next launch

The next Delta II launch will be NASA’s Deep Impact, which will launch in late December to encounter — and assault — Comet Tempel 1 on 4 July, 2005. The spacecraft is going through pre-launch preparations at Astrotech, and work to stack its Delta 7925 rocket on Pad 17B will begin on Monday, 22 November, with hoisting of the first stage into the launch mount.

20-Nov-04 | Delta flight 309 – Swift

Swift arrived safely in orbit on Saturday, 20 November, thanks to the efforts of Delta 309.

The launch was delayed for a couple of days by an issue with the vehicle’s command receiver decoder, equipment that can receive self-destruct commands from Range Safety in the event of a malfunction. That resolved, a unique issue cropped up overnight prior to the launch. At liftoff, ground support umbilical connections disconnect from the launch vehicle and are quickly retracted to the fixed tower on the pad. A cable that measures tension in one of the pullaway bungee cords that retract the umbilicals snagged somehow and could not be trusted to ensure proper retraction. Prior to fuel loading, a crew was dispatched to Space Launch Complex 17A, where they were able to lasso the cable and free it. The resolution took very little time, but nevertheless the launch team played catch-up for the rest of the terminal countdown. During the T-minus 4 minute hold, it became clear that all tasks could not be completed in time, and so the hold was extended for six minutes. This presented no problem for a one-hour launch window.

The Delta 7320-10C leapt off the pad at 12:16:00.611 EST and roared into the bright Florida sky, dropping its three spent booster motors about 66 seconds into the flight. Following second stage ignition, a “videoroc” showed a static-free shot of a payload fairing separation Boeing’s Marc Lavigne called “crisp.” Unlike several recent NASA launches, which carried several cameras, inside and out and facing fore and aft, this was the sole on-board video camera. It was mounted on the second stage, facing forward inside the fairing, and was mainly intended to show spacecraft separation. (Cameras ride aboard flights at the cost of payload capacity, and are only begrudgingly added in the planning stages of a mission. But “come launch day,” NASA launch manager Chuck Dovale commented, “everybody loves the camera.”)

The flight included three second-stage burns to place the spacecraft in its proper orbit. The first burn lasted about 5.5 minutes and ended in a nearly-circular parking orbit, 99.88 by 100.161 nautical miles, with an inclination of 28.47 degrees. A 16-minute coast phase was followed by the second burn of only about 32 seconds. This burn raised the apogee to about 334 nautical miles, and lowered the inclination to about 26 degrees. A longer, 44-minute coast came next as Swift and its Aerojet-built impeller rose toward apogee. Finally, a 54-second burn circularized the orbit at 324 nautical miles and 20.5° inclination.

Tracking was somewhat different than other recent flights due to the flight profile. As usual, early tracking and telemetry was provided by the Cape Canaveral Range and the Air Force’s tracking station on Antigua. The second of the three Aerojet burns, off the west coast of Africa, was followed by a station at Libreville, Gamon, and a mobile site deployed by the USAF at the small island of Sao Tomé. However, for unknown reasons Kwajalein was not able to relay data of the third burn as expected, and for several minutes the fate of the spacecraft was unknown. But the Hawaii tracking station came through in time for separation, and clean data and video both showed the release as the spacecraft faded into darkness. The second stage slowly backed away using gentle venting from its helium pressurization system in anticipation of its propellant depletion burn, and the flight was complete.

Swift is a gamma-ray observer that will have the capability to turn itself rapidly and view the afterglow of bursts in that wavelength. It will spend two years in orbit, helping scientists study massive star explosions and the subsequent formation of black holes. By the end of the day, Swift had unfurled its solar panels and was reported to be in an excellent state of health.

06-Nov-04 | Next launch

The next Delta II launch will be NASA’s Swift, presently scheduled for 17 November, and clear to be moved to SLC-17A now that Delta 308 has safely departed the neighbouring pad. Swift (not an acronym, but named for the small, nimble bird) is a gamma-ray observer that will have the capability to turn itself rapidly and view the afterglow of bursts in that wavelength.

06-Nov-04 | Delta flight 308 – NAVSTAR IIR-13

In the early morning hours of Saturday, 6 November, Delta flight 308 successfully placed NAVSTAR IIR-13 into a perfect transfer orbit to replenish the U.S. Air Force’s Global Positioning System.

After several postponements due to the hurricane season, a launch date of 30 October was delayed to change out batteries on the Delta third stage. The existing batteries had “exceeded their qualification margin” for power capacity. (In other words, weeks of delays left them worn out.)

The first launch attempt was made in the early hours of 05 November. A problem with a ground transmitter at one of the range tracking stations led to an extension of the built-in hold at T-minus 4 minutes; the liftoff time was reset to the last moment of the launch window. Then with less than a minute left in the resumed count, an alarm was triggered by a database problem in the launch data system, and a hold was called. With no time left to recycle to the 4 minute mark, the launch was scrubbed for the night.

After a 24-hour turnaround, all systems were go for a second try. The weather was vaguely coorperative, with a couple of cloud layers that were thin and broken enough to fly through, and gusty ground winds that approached but never violated the 25-knot rule. An unspecified range issue cropped up but was quickly resolved, and otherwise the terminal count was quiet and delay-free.

At the very opening of its launch window, 05:39:00.384 UTC, the three-stage Delta 7925 left SLC-17B and arced out over the Atlantic Ocean. The smooth flight, with two second stage engine firings, ended 25 minutes, 35 seconds later with spacecraft separation from its third stage motor.

Within the next few days NAVSTAR (Navigation Signal Timing and Ranging) IIR-13, Space Vehicle Number 61, will fire its onboard apogee motor to enter a circular, 11,000 n.m. operational orbit, where it will take over Plane D, Slot 1 from 2A-11, which launched aboard Delta 206 on 04 July 1991. This is a significant fact, as the average age of the 24 satellites presently in the Global Positioning System constellation exceeds the design lifetime of the satellites. For this reason, 5 more NAVSTARs are scheduled to be launched during 2005. This latest satellite was the last of the standard IIR (replenishment) models, as the next GPS satellite will be a “modernized” IIR-M model with an additional civilian signal and two encrypted military signals with improved resistance to jamming.



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