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History of the Delta Launch Vehicle

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12-Jul-05 | Deep Impact nails it

In the early morning hours of 04 July 2005, Deep Impact completed its mission by sending its impactor probe on a successful collision course with comet Tempel 1. The spacecraft recorded the spectacular plume generated by the high-speed encounter, and scientists have only begun to analyze the data.

The event apparently also generated intense public interest, as the Deep Impact web site logged 80 million hits in one 24-hour period, a new record for NASA (the previous record-holder was the landing of Mars Rover Spirit with 30 million hits).

20-May-05 | Delta flight 312 – NOAA-N

NOAA-N was successfully launched during the early morning hours of Friday, 20 May 2005, aboard a two-stage Delta 7320 rocket.

A perfectly routine countdown and adequate weather conditions at Vandenberg’s SLC-2W led to an on-time liftoff at the beginning of the window, with an official range time of 03:22:01.566 PDT. The Delta II Med-Lite vehicle quickly entered a low-hanging deck of clouds, and further tracking could only be provided by infrared camera and the announcements of the telemetry manager. SECO-1 occurred at T+11 minutes, 24 seconds, and the vehicle entered a long coast phase as it climbed to the apogee of a 100-by-468 nautical mile parking orbit.

At T+59 minutes, 26 seconds, the second stage restarted for a mere 13.3-second burn that circularised the orbit. At T+65 minutes, 44 seconds, the spacecraft was released into its operational orbit of 463.2 by 466.7 nautical miles at a 98.73-degree inclination. The Delta second stage then performed its evasive manoeuvre and depletion burn.

NOAA-N, to be known as NOAA-18 when operational, is a sun-synchronous polar-orbiting element of the POES (Polar Operational Environmental Satellites) constellation. In conjunction with the geostationary GOES system, which enables continuous but low-resolution sensing, POES provides highly detailed weather data as it travels in its relatively low orbit. A pair of POES satellites (NOAA-18 will operate in concert with NOAA-17, already in orbit) transmit images of the entire Earth’s surface every 12 hours.

16-May-05 | Delayed again

Another delay for NOAA-N, as a vent hose broke loose during Friday’s detanking operations, possibly contaminating the spacecraft with hydrocarbons, namely RP1 vapours. Inspections took place over the weekend and the results were expected to be discussed today. If all is well, a Launch Readiness Review on Tuesday will formally set a new launch date, which will occur no earlier than Thursday due to the proper orbital mechanics needed for launch.

13-May-05 | “Modernized” GPS delayed

The launch of the first NAVSTAR IIR-M for the Air Force’s Global Positioning System has been delayed indefinitely for unspecified reasons. In all, eight IIRs will be converted into IIR-Ms, which add a second signal for civilian use and two new encrypted signals for military use. The “M-Code” signals, scheduled to be fully operational by 2010, will have increased power and reduced vulnerability to signal jamming.

13-May-05 | Launch scrub

After two days of delays from high winds at Vandenberg AFB, launch of the National Oceanic and Atmospheric Administration’s newest weather satellite was again scrubbed on 13 May when the ground equipment that supplies the launch pad with cooling and sound-suppressing water suffered an electrical glitch. A 24-hour turnaround is in effect and the new launch time for NOAA-N is set for Saturday morning.

28-Apr-05 | News round-up

With a nearly-four-month gap between launches, Delta operations have been fairly quiet lately, with two routine vehicle stackings (one in Florida, the other in California) being not
particularly newsworthy. However, this is not quite the case for Delta-launched NASA missions. Here’s a round-up of the last couple months’ news…

The Spitzer Space Telescope (Delta 300) has returned images that appear to show, for the first time, an asteroid belt surrounding a distant star much like our sun. Two previous sightings of asteroid belts have surrounded younger, more massive stars, but this marks the first time that we have seen a star system with planetary formation that may be very similar to our own. Further observations are planned in order to confirm the suspected sighting. (20-Apr-05 NASA Press Release)

Mars Rovers Spirit and Opportunity keep on trucking along, and NASA has approved up to 18 more months of operations for the hardy explorers. This marks the third extension to the missions that have already completed more than 14 months of scientific endeavour, far exceeding the rovers’ design lifetime of three months. (05-Apr-05 NASA Press Release)

Nearly fifty years after the first Explorers discovered the Van Allen radiation belts, researchers at GSFC have found clues as to why the nested, toroidal belts have a radiation-free “safe zone” between them. A new theory states that lightning, occurring in the atmosphere hundreds of miles below the belts, generates radio waves that “clear the safe zone by interacting with the radiation belt particles, removing a little of their energy and changing their direction.” Data to support this theory were obtained by the Imager for Magnetopause to Aurora Global Exploration (IMAGE) spacecraft, launched aboard Delta 277 on 25 March 2000, combined with archival data from the Dynamics Explorer mission, which ran for more than nine years following its launch aboard Delta 155 in August 1981. (08-Mar-05 NASA Press Release)

IMAGE (Delta 277) and the venerable Polar spacecraft (Delta 233, launched in 1996) are allowing scientists to study both the northern and southern lights simultaneously, with the not-too-surprising result that Earth’s aurorae are not mirror images of each other and are much more complex than previously thought. (05-Apr-05 NASA Press Release)

This month the MESSENGER team completed checkout and commissioning of three of the components in the spacecraft’s Energetic Particle and Plasma Spectrometer (EPPS) instrument: the Fast Imaging Plasma Spectrometer (FIPS), the Energetic Particle Spectrometer, and the X-Ray Spectrometer. All are functioning normally, and FIPS has already spent some time observing the solar wind. MESSENGER was launched by Delta 307 in August 2004. (18-Apr-05 Status Report)

At an distance of 39.7 million miles, Deep Impact (Delta 311) spotted its quarry, Comet Tempel 1, on the very first attempt. This impressively early target acquisition will be a major aid in approach navigation. The high-speed impact of the spacecraft’s impactor module with the comet remains slated for 4 July. (27-Apr-05 NASA Press Release)

28-Apr-05 | NOAA-N repaired

NOAA-N has had its faulty S-band transmitter replaced and fully retested. The National Oceanic and Atmospheric Administration’s newest weather satellite was expected to be transferred to the pad at SLC-2W during the third week of April, and is on target for an 11 May launch.

12-Feb-05 | NOAA-N delayed indefinitely

The next Delta launch may turn out to be the first NAVSTAR IIR-M in May, as the launch of NOAA-N has been delayed indefinitely. During routine testing, one of the spacecraft’s four S-Band transmitters was found to have “an out-of-specification change” to its center frequency, which in operation would significantly hinder reception of the signal. Extensive diagnosis is now needed to determine the cause of the frequency shift. If the transmitter requires replacement, the delay will be lengthy, as “these units are not easily accessible.” (NASA ELV Status Report, 09-Feb-05)

18-Jan-05 | Phoenix

The folks at the University of Arizona’s Lunar and Planetary Laboratory have launched a newly-reorganized and informative web site for the Phoenix Mars Lander. Named for the mythical bird that is reborn from its own ashes, Phoenix is a retooled resurrection of the Mars Surveyor 2001 Lander, which was mothballed following the demise of Mars Polar Lander in 1999. It is the first mission in NASA’s Scout Program and is slated to fly aboard a Delta II-Heavy in mid-2007.

12-Jan-05 | Delta flight 311 – Deep Impact

The first launch from Planet Earth in 2005 was a Delta II, as flight 311 set Deep Impact on course to intercept Comet Tempel 1 later this year.

It was a picture-perfect launch as the Delta team threaded the needle of an instantaneous launch window at 13:47:08.574 EST on 12 January 2005. The three-stage Delta 7925, looking very much like a GPS satellite carrier with its standard 9.5-foot-diameter payload fairing, leapt from the pad at SLC-17B and rose into a clear Florida sky.

Upper level winds that had been a concern during the countdown had subsided, and the Delta second stage shut down after 9 minutes 46 seconds in a nearly-circular parking orbit of 89.95 by 90.28 nautical miles with an inclination of 29.735 degrees. The stage’s Aerojet AJ10-118K engine fired for a few seconds longer than planned to compensate for a first stage underperformance of unknown cause, but this too was well within flight parameters.

After about a fifteen minute coast phase, the second stage restarted for another burn, this one of about 1 minute 40 seconds, that raised the apogee of the orbit. This was followed by the third stage burn which sent Deep Impact into a hyperbolic escape orbit, on course for a comet.

Once again the telemetry downlink was spotty, a problem exacerbated by a flight apparently devoid of on-board cameras. The link with Ascension Island was lost toward the end of the second AJ10 burn, causing a swarm of people to crowd into the telemetry lab to attempt to read something that wasn’t there. The signal was restored by an Air Force tracking ship called OTTR near the west coast of Africa in time to see third stage spin-up and ignition, and telemetry was maintained through spacecraft separation.

The nail-biting wasn’t over for the Deep Impact team, however, as signals received at Canberra, Australia, were indeterminate as to whether its solar panels had deployed, an event that should have occurred soon after separation. Then, since no one had bothered to include Goldstone, California, in the tracking network, it was feared that controllers would have to wait until Deep Impact passed over Madrid, Spain, for further information — but a last-minute hook-up at Goldstone sent word that the panels were deployed and all was well, for the most part. It turns out that catalyst bed heaters in the spacecraft’s propulsion system briefly caused some temperature sensors to send an alert, which put the probe into safe mode until ground control could take a look at it. (The resulting shift to low-gain communication led to the difficulty in ascertaining the status of the craft.) Project managers suspect that the temperature limits were set a bit too low, and are confident that no hardware was damaged.

Deep Impact is the eighth mission* in NASA’s highly successful Discovery Program. Its principal investigators are with the University of Maryland, and the spacecraft was built by Ball Aerospace in Boulder, Colorado, under the management of the Jet Propulsion Laboratory. On 04 July 2005 it will send its “impactor” subassembly into a collision course with Comet Tempel 1, while the “flyby” module collects transmitted data and watches closely with sensors of its own. It is hoped that the impact will release ejecta that will provide clues to the composition of comets and, by extrapolation, the early solar system.

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