Thirteen months after the launch of their second ATV (Automated Transfer Vehicle) mission to the International Space Station, the European Space Agency have launched their third ATV to the ISS from the Guiana Space Centre, in Kourou, French Guiana. The ATV-3 spacecraft, highlighting the detailed work of NASA, ESA, and Russian officials, launched onboard the veteran Ariane 5 rocket at 0431 GMT (0031 EDT) Friday.
The launch sequence:
With an impressive safety and success record, Arianespace’s Ariane 5 rocket, flying in the Ariane 5 ES configuration, was the rocket used Friday morning to launch the ATV-3 to the International Space Station (ISS).
The voyage of ATV-3 marks the 61st flight of the Ariane 5, a rocket that first entered service on 4 June 1996 and has since evolved into five specific variants with only two complete failures of the rocket in its 16-year lifetime.
Standing 53 meters tall, the Ariane 5 ES rocket launched from its sea-side launch pad at ~0431 GMT (0031 EDT) to begin ATV-3’s journey to the ISS.
Ariane 5’s countdown was timed to result in a T-0 ignition of the core stage’s singular Vulcain 2 engine. The start sequence and post-engine start health verification checks took the countdown to T+7 secs, at which point the twin Solid Rocket Boosters ignited – resulting in the near-instantaneous liftoff of the Ariane 5 rocket.
After clearing its launch tower, the Ariane 5 rolled onto proper alignment, placing itself and its payload onto a 51.6 degree inclination to orbit, heading northeast out of the Guiana Space Centre over the Atlantic Ocean.
During the first two minutes of flight, Ariane 5 – like the Space Shuttle used to be – was powered primarily by its twin P238 Solid Rocket Boosters, or SRBs. Each booster was responsible for delivering 1.45 million lbf at liftoff – for a total liftoff lbf rating from the SRBs of 2.9 million lbf.
Aiding the twin SRBs in the first 129 seconds of flight was the Ariane 5’s core stage Vulcain 2 engine.
This singular engine delivered 301,000 lbf to the stack.
During “Stage 0” flight, each SRB burned for approximately 131 seconds, or 2 minutes 11 seconds before burning out and separating from the rocket at T+ 2 minutes 18 seconds (or thereabouts) at an altitude of 61km.
After SRB separation, the Ariane 5 continued its push toward space under the singular power of the Vulcain 2 engine.
Eight minutes 53 seconds after liftoff, at T+9 mins 00secs, the Vulcain 2engine completed its shutdown procedures, and the core stage separated from the EPS (Storable Propellant Stage, or Etage a Propergols Stockables) at an altitude of 133 km.
The EPS, carrying 10t of monomethyl hydrazine and nitrogen tetroxide burned by an Aestus rocket engine capable of providing 6,160 lbf, ignited for the first of two ATV-3 orbital boost phases at T+9 mins 7 secs – exactly nine minutes after liftoff from French Guiana in South America.
The first boost phase lasted until T+17 mins 10 secs, at which point a 45min 00sec ballistic coast phase took place.
Then, at T+1 hr 2 mins 10 secs, the Aestus engine reignited to begin the second boost phase. This phase lasted 30seconds and was used to circularize ATV-3’s orbit at 270 km.
However, the 61st flight of the Ariane 5 was not complete after the deployment of ATV-3. At T+2 hrs 24 mins 27 secs, the EPS’s Aestus engine was fired again for 16secs to drop it back into Earth’s atmosphere where it will burn up during reentry and thereby prevent itself from becoming a piece of potentially hazardous space debris.
The ATV-3, upon completing its five-day cruise to the ISS, will automatically dock the station on the end of the Russian Zvezda module.
While the precise time of docking is not known at this time and won’t be known until after the specific orbit ATV-3 is inserted into Friday morning can be analyzed, the craft will dock to the ISS on the night of March 28-29.
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ATV-3 highlights trilateral government agency cooperation advancements:
With a planned docked mission with the International Space Station lasting between four to six months, the third flight of the large-scale, government-owned premiere resupply vehicle from the European Space Agency – a multi-national space exploration agency consisting of the cooperation of 19 European nations – will continue a legacy of international support.
Riding on the success of its two immediate predecessors, the ATV-3, named Eduardo Amaldi after the 20th century Italian physicist, represents the direct cooperation between ESA’s constituent members, NASA, and Energia – part of the federal space agency of Russia.
Meeting in forums called Joint Operations Working Groups (JOWGs), the “Trilateral Operational Forum” between ESA, NASA, and Energia met a total of nine times by September 2011 to discuss operations specifically for the flight of ATV-3 – an impressive decrease from the total JOWGs for ATV-2’s launch which stood at 20.
Likewise, by the close of September 2011, only two (2) face-to-face meetings between the three international partners had been undertaken – again, a decrease from the three (3) total face-to-face meetings before ATV-2’s launch one year ago.
The decline in the number of meetings between the trilateral partners is clear evidence of the smoothing nature of the international vehicle visitation schedule and related dedicated procedures for each vehicle. It also speaks volumes of the success for the ATV series of vehicles.
Adding to this evidence is the impressive low number of Operational Change Requests (OCRs) for ATV-3 procedures following last year’s flight of ATV-2.
Prior to ATV-1, a total of 100 OCRs were requested.
Following ATV-1’s flight in 2008, a total of 32 OCRs were generated for ATV-2’s flight in 2011, of which 24 were accepted and implemented, five (5) were rejected, two (2) were withdrawn, and one (1) was carried over to ATV-3.
Discounting the carry-over OCR, only nine (9) OCRs were generated for ATV-3 following the ATV-2 mission for a total of 10 OCRs counting the carry-over.
Of these, two (2) were accepted, seven (7) remained open, and one (1) was withdrawn as of September 2011.
OCRs are “ESA ATV’s master tracking system for changes to Multi-Element Procedures (MEPs), Flight Rules, Operational Interface Procedures (OIPs), and Russian Operations Data File (RODF),” notes the ATV-3 Status to FOIG presentation from NASA’s Mission Operations Directorate – (available for download on L2’s ATV Special Section – Click here for L2 Link).
Highlighting the work of JOWG was a discussion and subsequent mitigation plan for ATV-3’s original March 5 launch date as of Sept. 2011.
According to the ATV-3 Status to FOIG presentation, “Russian Ground Site (RGS) Visibility During Docking: Due to Beta, RS/ATV docking target, and RGS visibility constraints, the docking window of ATV-3 was one day based off a March 5 launch.”
The RGS visibility constraint related to the fact that the targeted docking time of ATV-3, based on a March 5, 2012 launch, would have been “10 minutes prior to AOS (Acquisition of Signal) for the first RGS on Daily Orbit 2.”
According to the presentation, “This would allow for RGS comm coverage during ATV docking and RGS coverage on the next Daily Orbit should ATV need to be commanded to undock from ISS 110 minutes after docking.”
To solve this issue, the three international partners were able to come together and develop an alternative plan using USOS (United States Operating Segment) comm coverage while the Station itself is in “free drift” mode.
This resolution was made possible because of previous NASA experience with USOS comm coverage and Station free drift when Space Shuttle orbiters Endeavour and Discovery docked to the ISS during STS-130 and STS-133, respectively.
During these missions, relative motion between the two crafts after docking took longer to dampen out than previously seen, causing the Station/Shuttle complex to remain in “free drift” mode.
“20A (STS-130) and ULF5 (STS-133), which had extended free draft periods, were used to show that although in free drift, the ISS comm cover was still maintained through the majority of the passes,” notes the ATV-3 presentation.
Still another example of the cooperation was seen through the ATV-CC (ATV Command Center) Analysis of Full ISS attitude envelope.
“Currently, the approved attitudes allowable by the ISS and ATV differ significantly,” notes the presentation. “In order to have the same baseline constraints, ATV was requested to perform an analysis to encompass the approved ISS attitude envelope.”
This requested analysis was completed to allow ATV to have the same pre-approved attitude positions as ISS does. This avoids the need to create a CHIT and perform an analysis for each specific attitude option of ISS while ATV is docked.
This work has been completed for ATV-3 at this time.
(Images: L2, ESA and Arianespace)
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