United Launch Alliance’s Delta IV rocket has successfully deployed a pair of space surveillance satellites and a technology demonstrator for the US Air Force on Monday. With the initial attempt scrubbed via an issue with the ground support equipment environmental control system, the second, third and fourth attempts failed to avoid very poor weather over Cape Canaveral. Monday’s weather eventually turned green, allowing for a launch at 23:28 UTC.



Delta IV Launch:

The Air Force Space Command 4 (AFSPC-4) mission comprises two Geosynchronous Space Situational Awareness Program (GSSAP) spacecraft and the Air Force Research Lab’s Automated Navigation and Guidance Experiment for Local Space (ANGELS).

GSSAP is a four-satellite constellation being developed by the US Air Force to conduct visual monitoring of geosynchronous satellites. The first two spacecraft are being carried by today’s launch, with the remaining two expected to ride an Atlas V into orbit next year.

Built by Orbital Sciences Corporation, many details of the GSSAP spacecraft remain classified, however each spacecraft must have a mass of less than 1,000 kilograms (2,204 pounds) in order for the selected configuration of Delta IV to be able to deliver them into geosynchronous orbit. The spacecraft will fall under the control of the US Air Force’s 50th Space Wing.

The GSSAP spacecraft are not the first to be used to monitor geosynchronous satellites; in 2006 DARPA’s Microsatellite Technology Experiment (MiTEx) was launched by a Delta II.

Consisting of three satellites, the MiTEx mission consisted of an experimental space tug which was used to carry two inspection satellites from their deployment orbit to a near-geosynchronous trajectory.

Following a successful demonstration the spacecraft were used in 2009 to inspect the USA-197 satellite, a Defense Support Program missile-detection spacecraft which had failed after a little over a year in service. The technology developed and tested by the MiTEx program likely led directly to the GSSAP spacecraft.

In addition to these missions, the United States operated the Prowler satellite near geosynchronous orbit in the 1990s.

Although the US government has never acknowledged its existence, rumours about Prowler began to surface in the early 2000s and the satellite was identified by amateur observers after a 2009 European Space Agency survey found one more satellite in the geosynchronous belt than had been confirmed to have launched.

Designed for low-observability, Prowler was used to monitor geosynchronous satellites from primarily a signals intelligence perspective, studying communications between the spacecraft and the ground.

Prowler was deployed by the Space Shuttle Atlantis during November 1990’s STS-38 mission by means of a PAM-D upper stage. A Satellite Data System communications satellite was also deployed by the same mission, resulting in the combined deployment looking like that of a larger Orion signals intelligence spacecraft.

The ANGELS satellite, which has a mass of around 70 kilograms (150 lb), is a technology demonstrator which will be operated by the Air Force Research Laboratory. Also constructed by Orbital Sciences, this satellite is designed for one year of service.

It was attached to the Delta IV’s upper stage by means of an EELV Secondary Payload Adaptor (ESPA), from which separates after the Delta deployed its primary payload and made its disposal burn. The Delta IV’s spent second stage will serve as a target for rendezvous and station keeping trials as part of ANGELS’ mission.

The launch marked the 85th for United Launch Alliance, a company formed through the partial merger of the rocket development and launch service arms of Lockheed Martin and Boeing. Formed in December 2006, ULA is responsible for the production and launch of Atlas V, Delta II and Delta IV rockets.

The company is the prime contractor for launches of these rockets with payloads for the US Government, and conducts commercial missions under contract to Lockheed Martin and Boeing.

This was the Delta IV’s twenty-seventh flight on the mission. Numbered Delta 368, it flew in the Medium+(4,2) configuration which has been used for eleven previous launches. Along with the Atlas V, the Delta IV was one of two rockets developed introduced in 2002 as part of the US Air Force’s Evolved Expendable Launch Vehicle program to replace the older Atlas II, Delta II and Titan IV.

The Delta IV’s maiden flight occurred in November 2002, carrying the Eutelsat W5 communications satellite – now known as Eutelsat 33B.

Delta IV launches are made from both Cape Canaveral Air Force Station and Vandenberg Air Force Base. The launch took place from Space Launch Complex 37B (SLC-37B) at the Cape Canaveral Air Force Station in Florida.

Originally built for the Apollo program in the 1960s, the first launch from LC-37B was the Saturn I’s first orbital launch in January 1964.

All of the unmanned orbital launches of the Saturn I and IB rockets were conducted from LC-37B, with the nearby Launch Complex 34 being used for their suborbital launches and the manned Apollo 7 mission. Another pad, Launch Complex 37A, was built alongside LC-37B but was never used.

When Apollo’s Lunar missions began, the Saturn IB pads were mothballed in anticipation of further use in the 1970s when the envisioned Apollo Applications program would have seen further missions to low Earth orbit using Apollo hardware to conduct science in Earth orbit.

After this was cut down to just the Skylab and Apollo-Soyuz missions, NASA determined it would be more cost-effective to modify the Saturn V pad at Launch Complex 39 for Saturn IB missions than to reactivate one or more of the older complexes. As a result the launch of Apollo 5, the first test flight of the Lunar Module, became the last mission of a Saturn rocket from LC-37.

The towers at LC-37 were demolished in the 1970s, with the pad remaining derelict until its selection for the Delta IV in the late 1990s. In accordance with nomenclature introduced in 1997 the new pad is designated Space Launch Complex 37 rather than Launch Complex 37.

It was constructed close to, but not directly on top of, the original LC-37B. Delta IV launches from Vandenberg are made from Space Launch Complex 6, a former Athena launch complex which was originally built for the Titan III and subsequently renovated for the Space Shuttle – neither of which ever used flew from it.

The mission dropped the satellites off in a near-geosynchronous orbit, an unusual mission for one of the smallest Delta IV configurations but one made possible by the low mass of its payload.

To date the Delta IV Heavy is the only Delta IV to have launched satellites directly into geosynchronous orbit, excluding two early Delta IV Medium launches with Integrated Apogee Boost System (IABS) upper stages, which were considered part of the payload rather than part of the rocket.

According to its user guide, the Delta IVM+(4,2) is capable of placing 2,208 kilograms (4,870 lb) of payload into geosynchronous orbit. The Delta IV has a good record for reliability, with only one failure in its twenty six launches to date. That failure occurred during a 2004 test launch which was the maiden flight of the Heavy configuration.

The Delta IV’s first stage is a Common Booster Core (CBC), powered by a single RS-68 engine. Burning liquid hydrogen and liquid oxygen, the CBC ignited five second before launch, powering up to full thrust by the time the countdown reached zero.

At this point, the two GEM-60 solid rocket motors strapped to the first stage ignited and Delta 368 began her ascent, initiating a series of pitch and yaw manoeuvres eight seconds into flight in order to attain its planned trajectory for the ride into orbit.

Flying East over the Atlantic, Delta 368’s speed reached Mach 1 46.5 seconds after liftoff and the rocket passed through the area of maximum dynamic pressure, max-Q, 12.8 seconds later.

The twin solid rocket motors burned for 94.1 seconds, separating 5.9 seconds later; exactly 100 seconds after liftoff. The first stage’s RS-68 engine continued to burn until the four-minute, 5.3-second mark in the flight, with stage separation occurring six seconds later. Following staging the second stage began its prestart sequence.

For this mission the second stage was the four-meter version of the Delta Cryogenic Second Stage (DCSS). Based on the second stage of the short-lived Delta III rocket, the four-meter DCSS is the smaller of the two upper stages used by the Delta IV, with a five-meter version used on some missions.

The DCSS is propelled by a single RL10B-2 engine which features an extendable nozzle to improve its specific impulse, or fuel efficiency. Following deployment of its nozzle, the RL10 was lit fourteen and a half seconds after staging.

Separation of the payload fairing, which occurred 10.2 seconds into the first burn of the second stage, is the last event whose time has been confirmed in the mission profile.

As is typical for missions carrying intelligence satellites for the US military, coverage of the flight ended at this point, other than a statement on the outcome of the launch after spacecraft separation.

To accomplish a direct insertion, the Delta needed to fly for six to eight hours, making three upper stage burns.

The first burn of the Delta Cryogenic Second Stage placed the vehicle and its payload into a low Earth parking orbit; cutoff is likely to have occurred around twelve minutes after launch. The rocket was then expected to enter a coast phase ahead of the second burn, which will have likely occurred as the vehicle flies over the equator.

Such a burn can occur at either the descending node, as the rocket passes from the Northern hemisphere into the Southern hemisphere, or the Ascending node as it crosses from South to North.

An Ascending Node profile, given as a typical geosynchronous mission in ULA’s user guide, would call for this burn to occur on the first ascending node, around an hour and ten minutes after liftoff. The burn will have been shorter than the first, raising the apogee of the orbit to the altitude of the geosynchronous belt.

Following the end of the second burn, the rocket will have entered an extended coast, flying for over five hours to reach the apogee of its orbit. After attaining apogee, the third burn would have been conducted to circularise the orbit.

On an ascending node profile spacecraft separation would have likely occurred six and a half hours after liftoff, with the rocket subsequently making a collision avoidance manoeuvre to avoid adding to the debris in geosynchronous orbit. ULA confirmed the conclusion to the mission at around 7am GMT on Tuesday.

“The ULA team is proud to have delivered the twin Geosynchronous Space Situational Awareness Program (GSSAP) spacecraft to orbit today,” said Jim Sponnick, ULA vice president, Atlas and Delta Programs. “We are privileged to work with a top notch U.S. government and contractor mission team that is committed to mission success.

“This launch marks the first EELV secondary payload adapter (ESPA) to launch on a Delta rocket. This mission represents an excellent utilization of rideshare capabilities that has enabled a low-cost way for the AFRL ANGELS team to flight demonstrate future spacecraft technologies.”

The launch, following on from Russia’s scheduled deployment of Progress M-24 via a Soyuz-U rocket was the forty-fourth orbital mission of the year, and the third Delta IV flight of 2014, with the older Delta II having also made one launch.

The next Delta mission will be November’s flight of a Delta II carrying the Soil Moisture Active/Passive (SMAP) satellite, while the Delta IV will fly next in December as part of NASA’s Exploration Flight Test 1 (EFT-1) mission, the maiden flight of the Orion spacecraft.

The next launch for United Launch Alliance is currently slated for next Friday, with an Atlas V orbiting a Global Positioning System navigation satellite.

(Images via ULA, NASA and L2 Historical)

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