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History of the Delta Launch Vehicle



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20-Aug-09 | Delta flight 343 – NAVSTAR IIR-21 (M8)

On Monday, 17 August 2009, the last U.S. Air Force Delta II was launched from Cape Canaveral Air Force Station, placing a GPS satellite successfully into its transfer orbit.

As has become almost casually expected for a launch system that has now completed its 89th consecutive success, the terminal countdown for this flight encountered no major issues, and as dawn broke over the Florida coast, weather concerns—cumulus clouds and a chance of rain—dissipated. Liftoff occurred at the opening of the four-minute launch window, at an official range time of 06:35:00.231 EDT, with release into a nominal transfer orbit happening a little more than 68 minutes later.

NAVSTAR IIR-21 is the last of eight “modernized” replenishment spacecraft to join the GPS constellation. It will replace NAVSTAR IIA-26, an aging but still active bird that has lasted nearly twice as long as its seven-year design life since its launch in July 1996 aboard Delta 237.

Despite the success, this was a deeply melancholy event for all concerned, for this was the last time the Air Force would launch a vehicle that owed its very existence to that service. The Delta II rocket was developed by McDonnell-Douglas in response to an Air Force request for proposals following the loss of Space Shuttle Challenger in 1986, as a means to clear the resulting backlog in the launch manifest. The choice of Delta II reawakened a production line which had already been shut down, and resulted in a launch vehicle that has tallied one of the greatest records of reliability in the Space Age: over 99% in 144 launches. To date, all operational GPS satellites have been lofted on Delta II rockets: 49 in all, with only one of those failing to orbit.

Now, this chapter of spaceflight history has closed. The increased size and capability of future GPS satellites mean that they have outgrown the payload capacity of Delta II, and the Department of Defense will move to its two EELV options (Delta IV and Atlas V) for GPS as well as other missions. The launch also marked the final scheduled use of SLC-17A, one of two launch pads built at Canaveral in 1956 for the Thor ballistic missile program—a missile that formed the first stage of the original Delta model.

The military’s move away from Delta II, combined with budget concerns at NASA that prevent it from putting up enough missions to maintain the system singlehandedly, have resulted in the shutdown of the launch vehicle’s production line. A total of seven flights remain on the Delta II manifest—five from the west coast launch site at Vandenberg Air Force Base, and two from Canaveral’s SLC-17B. Another five vehicles have been built by Boeing and are in storage awaiting sale. After that, barring a major sea change in the industry, the Delta era—presently more than 49 years in the making—will come to an end.


15-May-09 | Delta flight 341 – STSS-ATRR

A two-stage Delta II model 7920, sporting a 10-foot-diameter composite fairing, successfully launched on Tuesday, 5 May 2009, carrying STSS-ATRR into orbit for the Missile Defense Agency.

Given the mission’s “quasi-classified” status, United Launch Alliance was precluded from webcasting the launch, and the best source for on-site updates turned out to be—once again—Justin Ray’s Mission Status Center at Spaceflight Now. Official range liftoff time from SLC-2W at Vandenberg Air Force Base was 13:24:25.757 PDT.

MDA was understandably tight-lipped about specific details, including payload size, mass, and target orbit. Nevertheless, that did not prevent spaceflight expert Jonathan McDowell from speculating on its design and mass in the latest Jonathan’s Space Report, nor independent observers from locating what they believe is STSS-ATRR in a near-circular polar orbit, roughly 470 nautical miles in altitude.

Most importantly, very little has been said about its onboard sensors and their capabilities, leaving the public with only the most general description of the spacecraft’s mission: “the Space Tracking and Surveillance System (STSS) Advanced Technology Risk Reduction (ATRR) mission… is a space-based sensor component of a layered Ballistic Missile Defense System (BMDS) to detect, track, and intercept ballistic missiles.” [ULA Mission Book]

STSS-ATRR is a $400 million pathfinder for future BMDS missions, testing the technologies that—if proven viable—will be incorporated into upcoming operational satellites. Another technology demonstrator is slated to launch on a Delta II later this summer. Both missions have seen more than their share of delays and cost overruns.


30-Mar-09 | Delta flight 340 – NAVSTAR IIR-20 (M7)

An early-morning Delta II launch from Cape Canaveral on Tuesday, 24 March 2009, has successfully placed another GPS satellite into orbit. Given the flight’s official range liftoff time of 04:34:00.244 EDT, this reporter slept through the whole thing—but Spaceflight Now‘s Justin Ray was awake and filed another entry in his continuing series of excellent mission status reports.

The flight marked the 87th success in a row for the venerable Delta II, a record dating back to 1997. There now remains only one Delta II launch for the Global Positioning System, currently scheduled for late summer.


28-Mar-09 | Delta flight 339 – Kepler

On the evening of Friday, 6 March, a three-stage Delta II 7925 launched NASA’s newest observatory, Kepler. The official liftoff time from Cape Canaveral’s SLC-17B was 03:49:57.465 UTC on 7 March. As usual, Spaceflight Now provided a complete play-by-play in its Mission Status Center.

Kepler is the first concentrated attempt at seeking out terrestrial planets—i.e., those roughly the size of Earth. It will do this by watching stars closely to spot the minute dimming caused by periodic transits of planets across the stars’ visible faces. Using Johannes Kepler’s Third Law of planetary motion scientists will be able to determine the planet’s orbit, and from there extrapolate its mass and estimated surface temperature. Thus they may figure out whether the planet might be capable of supporting life similar to that on Earth.


02-Mar-09 | Next launch

The next Delta II launch will be NASA’s Earth-size-planet hunter, Kepler. It is currently targeted for the late evening of 6 March EST (early morning 7 March UTC), pending a positive Flight Readiness Review today as well as confirmation of range availability by the USAF. The launch was delayed by one day to give engineers additional time to review possible hardware commonalities with the Taurus XL launch vehicle, which splashed NASA’s Orbiting Carbon Observatory last week after its payload fairing failed to separate properly.


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.


28-Oct-08 | Delta flight 336 – COSMO-SkyMed 3

In the last scheduled Delta II launch of 2008, a two-stage Med-Lite vehicle has successfully launched the third satellite in the COSMO-SkyMed constellation for the Italian Space Agency and the Italian Ministry of Defense.  The commercial launch was conducted by United Launch Alliance on behalf of Boeing Launch Services, and took place at Vandenberg Air Force Base SLC-2W on the evening of Friday, 24 October (liftoff time was 02:28:25 UTC, 25-Oct-08).

The flight, taking just under an hour from engine start to spacecraft separation, was the 84th consecutive success for Delta II, and its 43rd commercial launch success.  As usual, Justin Ray of SpaceflightNow.com provided an excellent play-by-play summary of the launch, available here.

Each COSMO-SkyMed satellite features a high-resolution, X-band Synthetic Aperture Radar to perform global Earth observation; data collected by the constellation of four will be provided to both the Italian military for national security, and the Italian scientific community for environmental studies.  The first three satellites in the constellation have been orbited aboard Delta II vehicles; the launcher for COSMO-SkyMed 4, slated for some time in 2010, is yet to be announced.


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