Europe’s ATV-3 docks to ISS – minor antenna deployment issue resolved

by Pete Harding

Europe’s Automated Transfer Vehicle-3 (ATV-3) “Edoardo Amaldi” resupply ship docked to the International Space Station (ISS) at 10:31 PM GMT on Wednesday, following a five day free flight after its launch atop an Ariane V booster from French Guiana on Friday. Meanwhile, a minor issue with ATV-3’s Antenna Deployable Boom (ADB) has been successfully resolved.

Launch and free flight summary:

ATV-3 enjoyed a nominal launch via the reliable European Ariane V booster on Friday morning, with ATV-3 being released into free flight following a final orbital circularisation burn by the re-ignitable Ariane V upper stage, which was de-orbited soon after.

Communications links with ATV-3 were quickly established by various ESA tracking stations around the globe, whereupon the ATV-Control Center (ATV-CC) in Toulouse, France began monitoring ATV-3’s onboard systems for the critical Launch & Early Operations Phase (LEOP).

Soon after separation from the Ariane V upper stage, ATV-3’s four power generating solar arrays were noted to be deployed nominally, a vital milestone since ATV’s rely on their onboard batteries charged by the solar arrays during free-flight.

One minor anomalous event was seen during an otherwise textbook LEOP, relating to ATV-3’s Antenna Deployable Boom (ADB) – the stick-like protrusion from the top of the ATV to which the S-band antenna is attached. The ADB is folded down during launch and is designed to deploy and lock into place once in space, however the ATV-CC did not receive the “ADB Locked” signal at the scheduled ADB deployment time.

This led to the unusual procedure of having the ISS crew take long-lens photography of ATV-3 as it passed roughly 100km below the station on Sunday morning (25th March), in order to visually verify that the ADB was fully deployed. The photography procedures were detailed in exclusive ISS on-orbit status notes available to view on L2 (L2 Link).

“ATV-CC requested that the ISS crew capture photos of the ATV prox antenna boom when it flies under ISS on GMT 085. There were indications that the boom may not be fully deployed to its 90 degree position.  The photo opportunity of ATV at its closest approach (107 to 115 km) was at GMT 17:09.”

“The ISS MER (Mission Evaluation Room) performed an assessment Saturday to remove the Cupola Window Scratch Panes from windows 5, 6, and 7 for the ATV-3 photos. This was the first time the scratch panes have been removed on-orbit.”

“The PTCS (Passive Thermal Control System) analysis showed the removal of the scratch panes was good for up to 4 hours before condensation became a concern. The actual time that power was removed was ~2.5 hours. There was no condensation reported by the crew. The crew removed scratch panes 5 and 6 only. The crew took approximately 40 photos.”

However, just as the crew photography was getting underway, the ATV-CC, who had just adjusted ATV-3’s attitude to provide the best possible photography angles, received the “ADB Locked” signal, thus confirming the ADB was deployed correctly.

“ATV-CC rotated the vehicle by -46 degrees in roll and +23 degrees in pitch.  Slew maneuver was completed by ~06:58 GMT.  At ~07:04, teams at ATV-CC reported telemetry in ATV-CC now shows the boom hinge status as deployed and locked at its 90 degree position. Initial theory is that ATV slew maneuver provided the torque to kick the boom into the locked position.”

Interestingly, the same issue was also seen on the ATV-2 mission in 2011, with the STS-134 crew tasked to photograph ATV-2’s ADB during their ISS flyaround in May 2011 in order to confirm the ADB was fully deployed.

Due to this issue, the ADB was slightly modified for the ATV-3 mission in order to prevent a recurrence of the problem, as noted to by a senior ESA official. “The RF (Radio Frequency) harness was somewhat rerouted, the MLI (Multi Layer Insulation) clearance improved, and the deployment procedure modified in order to achieve optimum thermal conditions”.

While the modifications clearly did not achieve their desired outcome, the ADB deployment issue is now fully resolved via the successful “ADB Locked” signal being received, and any possible lessons learned will be analysed and taken forward to future ATV missions.

The ADB issue successfully cleared the ISS Mission Management Team (IMMT), which consists of representatives of all the ISS international partners, on Monday, who formally declared that ATV-3 was “GO” for docking.

Rendezvous burns and docking procedures:

A major task for ATV-3 since it separated from the Ariane V upper stage was performing a precise sequence of engine burns in order to rendezvous with the ISS at its scheduled time. In total, an impressive 24 separate burns will be performed by ATV-3 between orbital insertion and docking, as detailed in an ATV-3 launch to docking timeline obtained by L2 (L2 Link).

Following ATV-3 separation from the Ariane V upper stage on Friday, Phasing Maneuvers TP1 and TP2 were performed, followed by Phasing Maneuvers MC1_1 on Saturday and MC1_2 on Sunday. Phasing Maneuvers TV1_1, TV1_2, TV2_1, and TV2_2 were then performed on Tuesday.

Wednesday saw by far the biggest amount of maneuvers, with Phasing Maneuvers TV3_1, TV3_2 and TV3_3 all being performed, whereupon ATV-3 marked the official start of the rendezvous phase with less than 12 hours to go until docking, and also reached the S-2 Waypoint, followed afterwards by the S-1 Waypoint. Phasing Maneuvers IF1, IF2 and IF3 were then performed, whereupon ATV-3 reached the S-1/2 Waypoint.

Working with the ATV prime contractor Astrium, an EADS company, Aerojet provided the four R-4D-11 110 lbf class liquid bipropellant engines for ATV maneuvering as the spacecraft approaches the ISS.

“Originally developed to provide reaction control for the Apollo missions to the moon, Aerojet’s R-4D rocket engines have been an integral part of human spaceflight for more than 50 years,” said Steve Harper, manager of the Bipropellant Propulsion product line at Aerojet.

“No R-4D has ever failed in flight during five decades of service with numerous missions, including the daring recovery of Apollo 13. We look forward to continuing this engine’s legacy of reliability with its use on the ATV, the Orion service module and other ambitious space missions.”

Homing Maneuvers HM1, HM2, HM3 and HM4 then followed, after which ATV-3 reached the S2 Holdpoint, which was followed by the last of the big rendezvous burns – Closing Maneuvers CM1, CM2, CM3 and CM4, whereupon ATV-3 arrived at the S3 Holdpoint and the start of the final phase of the rendezvous and docking.

Following departure of the S3 Holdpoint, ATV-3 passed through the S4 Holdpoint, followed by the S41 Holdpoint, followed after by a nominal docking to the ISS at the Service Module (SM) Aft docking port using the well proven Russian probe & cone docking system.

During the rendezvous phase, ATV-3 flew entirely autonomously, without any input from the ground, although the ground was monitoring the rendezvous and gave permission for ATV-3 to proceed with the automated sequence after each Waypoint/Holdpoint.

As ATV-3 moved closer to the ISS, its internal navigation switched from using star trackers, to absolute GPS, to relative GPS at 30km from the ISS, to a laser link at 250m from the ISS, and finally used a video target system which enabled the crew aboard the ISS to monitor the approach in the final phase of docking.

UK company e2v recently noted the use of their hardware as a key part of enabling ATV-3’s docking with the ISS, namely e2v’s CCD47-20 imaging sensors – which were selected by SODERN as part of the two key systems they delivered for the ATV; an SED16 star tracker, an optical device used for determining the orientation of the spacecraft by measuring its position relative to stars, and a Videometer, a system SODERN developed which is the primary rendezvous and docking sensor for the spacecraft.

Built under Astrium prime contractorship, the first and second ATVs (Jules Verne and Johannes Kepler) were also equipped with these e2v imaging sensors and successfully completed their missions in 2008 and 2011 respectively.

“Edoardo Amaldi is the third ATV to have been successfully launched into space,” noted e2v’s Jon Kemp. “e2v’s imaging sensors are a key component in enabling the ATVs to successfully dock with the ISS and provide essential support to the astronauts onboard.”

ATV-3 maintained communications with the ISS through the proximity link via the S-band antenna atop the fully deployed ADB.

Aboard the ISS, inside the Service Module, Russian cosmonaut Oleg Kononenko and ESA astronaut André Kuipers monitored the rendezvous and docking, with the ability to manually abort it if necessary – however, unlike the manual TORU system used for Russian Progress dockings, they did not have the ability to manually fly ATV-3.

Following a nominal docking, ATV-3 became the first vehicle to dock at the SM Aft port in the post-Space Shuttle era, as the previous vehicle was Progress M-11M in June last year, which, following it’s undocking on 23rd August and the failure of the Progress M-12M launch on 24th August, resulted in the unusual situation of the SM Aft port being “open” for precisely six months.

Attached phase operations:

Now successfully docked, ATV-3 will enter into attached Phase Operations, with the first order of business being the opening of ATV-3’s hatch, an activity which is not scheduled until Thursday, as leak checks first need to be performed.

The attached phase operations are scheduled to last just over five months, during which ATV-3 will essentially be considered as another module of the ISS – which, although docked to the Russian Segment (RS) of the ISS, will technically be considered part of the United States Orbital Segment (USOS).

ATV-3’s 6,596 kg of cargo (covered in a previous article on – including both internal, or “dry” cargo, and water/gases/fuel, or “wet” cargo – will be transferred to the ISS over the course of the next five months, whereupon ATV-3 will be filled with trash to be disposed of when ATV-3 undocks from the ISS, currently tentatively scheduled for 3rd September.

Using its now highly reliable propulsion system, ATV-3 will also be responsible for ISS reboosts, Debris Avoidance Maneuvers (DAMs), and attitude control propulsive support during its five month docked mission, thus relieving the Service Module engines of their unusually heavy reboost duties of the past six months, due to the aforementioned lack of any docked vehicles at the SM Aft port since late August last year.

Current preliminary ATV-3 reboost dates are 31st March – which will be a one-off test reboost to verify the performance of ATV-3’s propulsion system – followed by standard reboosts on 5th April and 25th April.

These dates however depend heavily on the schedule of other Visiting Vehicles (VVs) to the ISS – with ATV-3 slated to meet two Soyuzes, two Progresses, at least one SpaceX Dragon, and its old friend from 2011, the HTV, at the ISS before its departure – in addition to the two Soyuzes and one Progress already present at the station.

The ATV-3 mission will be a baptism of fire for the European Space Agency – who not only will have to run mission operations with ATV-3 for nearly half of the year, but also gear up to launch the ATV-4 “Albert Einstein” vessel to the ISS less than one year from now. ATV-3 is the first “production” ATV, targeted to launch at a rate of one per year, thus fulfilling a vital role as the largest ISS resupply craft, helping to support the station in the post-Shuttle era.

Please follow ESA’s ATV blog for additional ATV-3 mission updates.

(Images: L2, ESA, and e2v)

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