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Archive for 2009

12-Feb-09 | Orbital collision “worst ever”

An active Iridium satellite collided with a defunct Russian military communications satellite over Siberia on Tuesday, 10 February, destroying both spacecraft.

The impact—at around 425 nautical miles altitude and a closing speed of roughly 7 miles per second—generated a massive debris cloud that is still being assessed; it has the potential to rival the one created by China’s infamous impactor test in 2007. This will pose an increased risk to many satellites in orbit at similar altitudes, including the rest of the Iridium constellation; NASA’s “A-Train” of Earth observers; and the latest-generation weather satellite NOAA-19, launched just last week aboard Delta 338.

The Iridium satellite is one of 46 launched in 1997; some 30 satellites were launched aboard Delta flights 242, 244, 246, 248, 250, and 251. Another 14 flew on Russian Proton vehicles, and 2 more on a Chinese vehicle. The satellite involved, Iridium 33, launched with 6 siblings aboard a Proton on 14-Sep-97.

06-Feb-09 | Delta flight 338 – NOAA-N′

The third try was the charm this morning as a two-stage Delta II Med-Lite model 7320-10C lofted NOAA-N′ into orbit for NASA and NOAA, the National Oceanic and Atmospheric Administration.

Following two previous attempts that were scrubbed due to issues with ground support equipment, and a weather report that threatened rain and gusty winds, Friday’s countdown was smooth and trouble-free. The wind gradually subsided to within limits and despite numerous COLA blocks the Delta II was able to lift off at the opening of its ten-minute launch window, at 02:22:01 PST.

As a steady breeze blew ragged wisps of fog across SLC-2W, the rocket’s main engine and three booster motors lit up the night before swiftly disappearing into a cloud layer. The low ceiling forced the television feed to switch to a computer-generated flight simulation for the remainder of the flight. Fortunately the telemetry feed was solid throughout—except of course during scheduled data blackouts between tracking stations—and telemetry manager Steve Agid provided a steady patter of precision play-by-play from across the country at Cape Canaveral.

Just under 66 minutes after launch, the Aerojet-built second stage released the spacecraft into an orbit “right on the money,” according to NASA launch manager Omar Baez, before performing an avoidance manoeuvre and propellant depletion burn.

Once it was in its circular, sun-synchronous orbit, NOAA-N′ (“N-Prime”) was renamed NOAA-19. It is billed as “the last in the TIROS (Television and Infra-Red Observing Satellite) series” of Earth-observing weather and environment satellites, and “will provide global images of clouds and surface features and vertical profiles of atmospheric temperature and humidity for use in numerical weather and ocean forecast models, as well as data on ozone distribution in the upper part of the atmosphere, and near-Earth space environments—information important for the marine, aviation, power generation, agriculture, and other communities.”

The TIROS series extends back nearly 50 years and is, with a few recent exceptions, closely tied to the Delta launch vehicle. TIROS-1 was launched in 1960 aboard a Thor-Able, the direct predecessor to the original Delta. Subsequent missions upgraded the original technology of TIROS with a succession of nested acronyms including TIROS Operational System (TOS) and Improved TOS (ITOS). Some 28 flights including the one today were performed by various models of Delta vehicles. (Only two of these, both in the early 1970s, failed to orbit.) NOAA-19 will replace NOAA-18, which launched aboard Delta 312 in May 2005.

This marks the 85th success in a row for Delta II, a testament of extreme reliability for a launch system which will celebrate the 20th anniversary of its first launch one week from tomorrow.

05-Feb-09 | Another equipment failure scrubs launch

The second attempt at launching NOAA-N′ was scrubbed this morning due to a problem with the launch pad system that feeds conditioned air into the payload fairing. Managers do not believe any damage was caused to the spacecraft, but a cursory contamination check will be needed to determine whether any hydrocarbons were introduced into its clean environment. A decision on the next launch opportunity is expected around mid-day Thursday; another launch window opens on Friday at 10:22 UTC.

Update for 21:35 UTC: Air samples from the payload fairing and the ground support system are reported clean, so officials have cleared the way for a Friday morning launch attempt. The weather remains at a 60% chance of violating launch criteria.

04-Feb-09 | NOAA-N′ scrubbed

The first Delta II launch of 2009 will have to wait at least one more day. Today’s launch of NOAA-N′ (“N Prime”) for NASA and the National Oceanic and Atmospheric Administration was scrubbed during the built-in hold at T-minus 15 minutes due to faulty ground support equipment. A routine check of the gaseous nitrogen system at Vandenberg’s SLC-2W found it to be undercharged, a potentially hazardous condition since the system is used to purge the vehicle’s first-stage tanks during detanking operations.

Launch controllers are hopeful for a 24-hour turnaround and the opportunity for a launch early Thursday. Unfortunately, today’s good weather is not expected to last, and the forecast for tomorrow expects an 80% chance of violating launch criteria, with low clouds, rain, and gusty winds. Somewhat better odds are predicted for subsequent launch windows through the weekend.

Update for 22:30 UTC: Engineers have replaced a faulty relay on the gaseous nitrogen purge system, and the weather report has improved somewhat with the potential for thick clouds having a 60% chance of violating launch criteria. A second launch attempt will be made tonight.

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