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History of the Delta Launch Vehicle



Current Delta News

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10-Jun-11 | Delta flight 354 – SAC-D/Aquarius

A two-stage United Launch Alliance Delta II rocket lifted off into a thick fog early this morning, Friday, 10 June 2011, from California’s Vandenberg Air Force Base. Aboard was the SAC-D/Aquarius spacecraft, a joint mission of Argentina’s National Commission on Space Activities (CONAE) and NASA. The launch vehicle performed as expected, placing the spacecraft into a circular, sun-synchronous polar orbit some 56 minutes after launch. Official liftoff time was 14:20:13 UTC.

Satelite de Aplicaciones Cientificas-D, the second SAC spacecraft to launch aboard a Delta II, is festooned with several Earth-sensing scientific instruments supplied by different countries. Primary among these is NASA’s Aquarius sensor, which will gauge ocean surface salinity levels. Data from Aquarius is expected to fundamentally impact our understanding of the world’s oceans in terms of circulation, climate, and water cycle.

This was the 94th consecutive successful launch by Delta II, a world-record series of successes dating back to May 1997. It was the first of three planned launches for Delta II this year—all of them for NASA, and the final flights on the schedule. Five Delta II vehicles remain in storage, complete and awaiting assignment.

07-Jun-11 | Next launch

Update for 8 June: Launch has been postponed for 24 hours due to a technical issue.

The first of three Delta II launches slated for 2011 is on schedule for departure on Thursday, 9 June. The 5-minute window opens at 07:20:13 PDT at Vandenberg Air Force Base, where a two-stage Delta II 7320 stands ready to put the SAC-D/Aquarius spacecraft into orbit for the Argentina National Commission on Space Activities and NASA. The Flight Readiness Review was completed on 2 June, and loading of the Delta II second stage with hypergolic propellants was performed a day later.

06-Apr-11 | High launch costs may lead to fewer NASA missions

With the last few Delta II missions already slated and no desire to cover the high cost of continuing that launch system, NASA now finds itself with a not-unexpected dilemma: no affordable means to get small- and medium-class spacecraft off the ground. Spaceflight Now has the full story.

09-Nov-10 | Delta flight 350 – COSMO-SkyMed 4

The 93rd consecutive success for Delta II has completed a radar-imaging constellation for the Italian military and government.

The launch of COSMO-SkyMed 4, from Vandenberg AFB on Friday evening local time (02:20 UTC on 6 November 2010), went off without issue after three previous attempts were scrubbed, two for main engine compartment heating systems, one for a low voltage reading in the second stage battery. As usual, Justin Ray provided a complete play-by-play in Spaceflight Now’s Mission Status Center.

This was the only Delta II launch for 2010, and the final scheduled commercial flight for the venerable rocket. Three flights for NASA are slated for 2011, and five vehicles remain unassigned. Boeing hopes to find commercial customers for those remaining rockets.

02-Nov-10 | Third scrub

With less than a minute remaining in the countdown of Delta 350, a hold was called due to a second stage battery voltage alarm. Since COSMO-SkyMed 4 requires an instantaneous launch window to reach its precise orbit, the hold resulted in a scrub for this third attempt to launch. The launch team will take a day of rest before making another attempt on Thursday evening. [UPDATE: the attempt was rescheduled to Friday when analysis determined that Thursday’s launch window would not provide optimal placement into the constellation.]

02-Nov-10 | Second scrub

A second shot at launching Italy’s COSMO-SkyMed 4 was scrubbed last night with about 2 minutes left in the countdown. Engineers noted insufficient flow in a gaseous nitrogen purge system in the vehicle’s main engine section, meant to “ensure that critical components in close proximity to cryogenic propulsion systems are kept warm,” according to a ULA press release. No word on whether this is related to the heater issue that scrubbed the previous night’s launch. A third attempt is scheduled for Tuesday evening, November 2 (local time).

31-Oct-10 | Launch scrubbed

A Halloween-evening launch—the only scheduled Delta II flight of 2010—has been scrubbed. An unspecified technical issue brought a halt to proceedings about 25 minutes before the instantaneous launch window, set for 02:20:07 UTC on November 1. [UPDATE, 1 Nov 16:45 CDT] A heater meant to keep the engine section warm during fueling failed to operate. A second attempt will be made this evening.

04-Feb-10 | NASA budget restructures NPOESS, leaves NPP intact

The White House’s FY2011 budget, much in the news this week for having forced NASA to abandon its Constellation program and a planned return to the Moon, has implications for our ongoing understanding of climate change that are at least as significant as those for human spaceflight. More

14-Dec-09 | Delta flight 347 – WISE

Today marked the start of a new era in astronomy as NASA’s Wide-field Infrared Survey Explorer (WISE) spacecraft took flight and was successfully placed into its polar orbit by the venerable Delta II launch vehicle.

At 06:09:33 Pacific Standard Time (14:09:33 UTC), Space Launch Complex 2-West at Vandenberg Air Force Base lit up with the fire and thunder of WISE’s Delta 7320-10C Med-Lite vehicle. With only two stages and three strap-on booster motors, the 7320 has the least total impulse of any of the Delta II vehicles; nevertheless it had plenty of oomph for WISE, a lightweight craft that weighed less than three-quarters of a ton—1,457 pounds—at liftoff.

This marked the 92nd consecutive success for Delta II, an exemplary record dating back over a dozen years. In addition, the United Launch Alliance has now tallied 37 consecutive successes—one hundred percent—in its 36 months of existence. (Delta II accounts for 21 of them.)

The Wide-field Infrared Survey Explorer will survey the entire celestial sphere at least once during its nine-month mission. It is a follow-on to IRAS and COBE, two infrared surveyors that each launched aboard Delta vehicles—Delta 166 (25-Jan-83) and Delta 189 (18-Nov-89), respectively. The sensor package aboard WISE has a sensitivity at least a thousand times greater than those of its predecessors, made possible by a cryostatic system that uses solid hydrogen to keep cool. The hydrogen, weighing 35 pounds at liftoff, will gradually heat and boil away into the near-vacuum of space; hence the short mission duration.

WISE is part of NASA’s Explorer program, a series of scientific spacecraft that is older than the agency itself. More than three dozen Explorer missions have been lofted by Delta rockets, several of them still active—among them XTE, ACE, WMAP, and Swift. However with the Delta II production line shut down, and only five launch vehicles left unassigned, it is very possible that today’s launch will be the last teaming of Explorer and Delta.

10-Dec-09 | Launch delayed (update for 11-Dec-09)

The next launch of a Delta II rocket, carrying NASA’s WISE infrared surveyor, has been postponed by three days. During final checkout on 9 December, one of the vehicle’s main-stage vernier engines was found to have excessive resistance to movement. A suspect component will be swapped out. The twin vernier engines flank the Delta II main engine and provide the primary roll control (as well as some pitch and yaw control) during the first stage of flight.

Liftoff is now scheduled for Monday, 14 December, at 14:09 UTC (06:09 local time at Vandenberg’s Space Launch Complex 2-West).

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