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History of the Delta Launch Vehicle

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08-Feb-08 | ULA “not backing away from Delta II”

Last week the United Launch Alliance announced a restructuring of the Delta II program, “building upon its unparalleled record of mission success to make it more cost effective in a challenging market.” (ULA Press Release, via Spaceflight Now) Under the leadership of program director Rick Navarro, ULA will strive to remain “at the forefront of the medium-lift market.”

On the surface, the statement is vaguely reassuring with regard to Delta II’s future. However, it addresses few specifics of the restructuring plan, and “remain[ing] positioned to offer high reliability and competitively priced launch products to support the market needs” does not necessarily preclude a mothballing, temporary or otherwise, of America’s premier workhorse for spaceflight.

28-Jan-08 | Reentering spy satellite may have been Delta payload

Numerous news sources (AP via the Washington Post, The New York Times, Observer, Globe and Mail) have reported a U.S. spy satellite that is out of control and is expected to fall back to Earth some time in late-February or early-March. Although the government is not providing specifics on the spacecraft, speculation is pointing toward the National Reconnaissance Office’s L-21, also known as USA 193, which launched aboard Delta 322 in December 2006. L-21 “carried sophisticated cameras to take high-resolution pictures and test equipment intended for use on the broader Future Imagery Architecture (FIA) program”[Reuters] and was delivered into the correct (low altitude, high inclination) orbit by its two-stage 7920 vehicle, but was soon declared a loss due to its failure to communicate with ground control.

Early estimates of its size—“about 20,000 pounds and the size of a bus”—presumed that the satellite is one of the massive Keyhole-class spy birds that were once launched aboard giant Titan-IV rockets. If it is L-21 instead, these figures would be grossly overstated. L-21’s weight was classified “for official use only,” but given the payload capacity of the Delta II it would have been on the order of 4,000 pounds and about the size of a four-door sedan.

Since it cannot be controlled, there is no way of knowing exactly when and where the satellite will reenter the atmosphere. Most news outlets are focusing on the potential of the debris to damage something, or injure someone, both of which carry relatively insignificant odds. Given the highly-classified nature of the satellite—independent observers have been unable to determine even the most basic parameters of it, such as whether it was designed to use solar panels—it may be more pertinent to consider the potential for sensitive technology to fall into the wrong hands.

Another issue that has been raised is the possibility that L-21 might carry a radioisotope thermoelectric generator, or RTG, as its power source. Whether this is the case is unclear: the NRO refuses to confirm or deny; a professional analyst deems it “unlikely,” yet is the same person who overestimated the size of the craft; meanwhile amateur skywatchers have published grainy photographs of L-21 that purport to show a lack of solar panels, implying an alternative power source. Regardless, current RTG design makes the chance of a containment rupture fairly remote, even in the case of a hard landing, and the fuel pellet is in a ceramic form that resists heating and vaporization; the odds of environmental impact are extremely low. (In the case of close contact, the highly corrosive hydrazine thruster fuel poses a greater health risk, and the U.S. military is developing contingency plans to quickly retrieve any debris should L-21 end up on land.)

23-Jan-08 | MESSENGER on course, data dump complete

On 18 January the MESSENGER team announced that the spacecraft missed its targeted aim point by a mere 5.12 miles—not too shabby considering the billions of miles it has already travelled, and well within nominal. The gravity assist it received from Mercury put it on course for the next fly-by in October. A trajectory correction known as DSM-3 is expected some time during that cruise. Meanwhile, data from the fly-by have been received on Earth, and the handful of images released so far have been spectacular.

15-Jan-08 | MESSENGER survives Mercury Flyby 1

Yesterday MESSENGER survived its first encounter with Mercury, collecting extensive data as it passed a mere 124 miles above the surface. Today, following further departure observations, it will turn its antenna back toward Earth to begin the downlink process. The initial results will not be announced until a press conference scheduled for 30 January, although some excellent early photos have started to trickle out. The spacecraft is reported to be “still operating nominally,” but there has been no word yet on whether the trajectory change caused by the gravitational assist was on target.

10-Jan-08 | MESSENGER on course for first Mercury fly-by

NASA’s Mercury probe MESSENGER will pass within 124 miles of the First Rock from the Sun on Monday, 14 January 2008. It will make its closest approach at 19:04 UTC. This will be the first mission to provide a close-up view of the mysterious little planet since Mariner 10 made its third and final fly-by in 1975, nearly thirty-three years ago.

The mission team has been receiving and analyzing batches of optical navigation images for the past few days, in order to determine the spacecraft’s exact position relative to Mercury and to ascertain whether any trajectory corrections are needed to remain on course. As yet no adjustments have occurred since the regularly-scheduled TCM-19 on 19 December, and a 10 January follow-up burn was cancelled. The team will continue to monitor these navigational images until shortly before the fly-by, when course corrections will no longer be possible and the spacecraft’s instruments will be turned toward the planet.

MESSENGER (short for “MErcury Surface, Space ENvironment, GEochemistry, and Ranging”) was launched by Delta 307 in August 2004. Along with providing some early science returns, the fly-by is a gravity assist manoeuvre to alter MESSENGER’s trajectory. The spacecraft will pass Mercury twice more before settling into orbit in March 2011.

20-Dec-07 | Delta flight 331 – NAVSTAR IIR-18 (M5)

A Delta II 7925 today lofted another Global Positioning System replenishment satellite for the U.S. Air Force.

Liftoff was delayed by five minutes after the opening of the fourteen-minute launch window due to a collision avoidance period, or COLA, which is a common occurrence in launches since there are so many objects already in orbit. Despite the COLA, the countdown was without major issues, and the three-stage Delta II left the pad at Cape Canaveral’s SLC-17A with an official range liftoff time of 20:04:00.353 GMT.

Fifty-eight minutes later, the GPS satellite was released into its nominal transfer orbit, which is an elongated path of about 11,000 nautical miles in apogee. The satellite will fire its own onboard AKM within the next several days to circularise its orbit. It will enter Plane C, Slot 1, replacing IIA-24, which will move to Plane C, Slot 5 to replace IIA-20. (IIA-24 was launched aboard Delta 226 in 1994. IIA-20 was launched on Delta 220 in 1993, and has more than doubled its seven-year design lifetime. It is showing signs of its age and will be decommissioned.)

This was the 46th launch of a GPS satellite by Delta II, all but one of which have been successful. (A further 11 experimental GPS satellites were launched on Atlas vehicles between 1978 and 1985.) It was also the 79th consecutive successful launch for Delta II, a continuing world record.

10-Dec-07 | Delta flight 330 – COSMO-SkyMed 2

On the evening of Saturday, 08 December 2007, a two-stage Delta II Med-Lite launched the second in a constellation of Italian radar satellites known as COSMO-SkyMed. The launch from Vandenberg Air Force Base’s SLC-2W occurred at an official range liftoff time of 18:31:42.118 PST (02:31:42.118 GMT on 09 December).

At 58 minutes 4 seconds after launch, the satellite was deployed into a near-circular polar orbit. When it becomes operational, COSMO-SkyMed 2 will join its siblings in providing environmental monitoring, resource management and territorial surveillance for the Italian Space Agency and the Italian Ministry of Defence. COSMO is an acronym meaning “COnstellation of small Satellites for the Mediterranean basin Observation”, intriguingly not an Italian phrase. (No word on the meaning of SkyMed, which this author suspects is the IMoD name for the constellation.)

Delta II continued its longest-ever success record with this flight, the 78th in a row. As usual, Spaceflight Now’s Justin Ray provided an excellent play-by-play here.

Amidst the excitement of a successful deployment, it was announced that COSMO 3 will launch aboard another Delta II in the second half of 2008. The launcher for the fourth satellite in the constellation has not yet been chosen—several competitors are vying for the contract.

07-Dec-07 | Another scrub for COSMO 2

Strong winds at Vandenberg prevented pullback of the mobile service tower today. A 24-hour turnaround is in work; Saturday’s liftoff is set, as on previous days, for 6:31 p.m. PST (02:31 on 09 December GMT).

06-Dec-07 | COSMO-Skymed 2 scrubbed, delayed

Yesterday’s attempted launch of the Italian COSMO-SkyMed 2 satellite was scrubbed with less than three minutes left in the countdown, when a high-altitude weather balloon reported unacceptable upper-level winds. The Delta II vehicle was safed at SLC-2W and the launch team immediately began preparations for a 24-hour turnaround.

However, during post-scrub inspections it was found that some cork insulation had debonded and will need to be reattached. The insulation is used to protect portions of the first stage from hot gases that can impinge on the vehicle’s skin during liftoff and flight. This cork—and it is in fact real cork wood, a low-tech but suitable solution that has been used on Delta for years—has come loose on vehicles in the past, and repair is usually trivial and quick to complete.

Launch is now tentatively scheduled for Friday evening, 7 December.

17-Oct-07 | Delta flight 328 – NAVSTAR IIR-17 (M4)

A three-stage Delta II rocket successfully sent a new Global Positioning System satellite into orbit today for the U.S. Air Force. The launch continued Delta II’s unprecedented string of successes, now numbering 77 in a row.

Terminal Countdown, which starts at T-minus 150 minutes, got underway today at 05:23 EDT—two hours before sunrise at Cape Canaveral—and proceeded like a finely-tuned watch. Weather conditions were thought to have a 40% chance of violating launch criteria, with the possibility of scattered rain in the area. As the countdown progressed, a 10-knot wind from the east caused the boil-off exhaust of the liquid oxygen tank to form a lengthy, horizontal plume. However by launch time upper level winds were seen to be within limits, the temperature was around 78°F, and the blue morning sky with a few scattered clouds offered smooth sailing.

The Delta II 7925 lifted off from SLC-17A at an official range liftoff time of 08:23:00.258 EDT, right at the opening of today’s 15-minute launch window. First stage flight occurred nominally, followed by a pair of second stage burns separated by a 52-minute coast phase.

Telemetry from the launch vehicle cut out after third stage spin-up and separation from the second stage, leaving flight controllers in the dark during the third stage burn and spacecraft separation, which were expected to be completed just over 68 minutes into the flight. It took another fourteen minutes or so for the Air Force to announce that it had established contact with the spacecraft and that all events had transpired normally. Delta II placed the satellite into an elliptical transfer orbit, the standard for GPS launches. Within the next few days the spacecraft is expected to fire its onboard AKM to place itself into operational orbit.

NAVSTAR IIR-17 is the 45th GPS satellite to be launched by Delta II, and is the fourth of eight “modernized” IIR satellites that provide an added signal for civilian use and two new encrypted signals for military use. It will enter the Plane F, Slot 2 position to replace IIA-14, which was launched aboard Delta 211 on 7 July 1992 (and which has far exceeded its seven-year design life). Another NAVSTAR launch is expected before the end of the year.

United Launch Alliance provided a good quality live video stream of the launch, but about ten minutes before liftoff the feed turned into loud static for about fifteen seconds. When it returned, the picture was fine, but all the audio sounded like it was being fed through a kazoo. -ed.

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