Europe’s ATV-5 completes docking swansong with the ISS

by Chris Bergin and Pete Harding

The European Space Agency (ESA) ATV-5 has completed her final ever docking to the International Space Station (ISS). The “Georges Lemaître” is conducting an essential cargo run to the orbital outpost, with her pre-arrival orbital adventures also including a key test of sensors that could help spacecraft that follow in her footsteps. The vehicle successfully docked at 13:30 UTC on Tuesday.

Rendezvous and docking:

The ATV spent 14 days on orbit, following her July 29 launch atop of an Ariane ES booster from the Kourou spaceport in French Guiana.

Her move toward docking day had been relatively trouble-free, with only a “Propulsion Drive Electronic -PDE1 failed” listed on L2 ATV-5 Status information.

However, that issue was soon removed on August 4, via what was described as a “successful reintegration”.

“Since launch on 29 July, ATV has conducted a series of manoeuvres to bring it up to the Station altitude, and these have gone flawlessly,” noted Jean-Michel Bois of the ESA operations team.

“The vessel is functioning perfectly and we are looking forward to a smooth – and final – ATV docking.”

Following these altitude-rising burns, rendezvous operations entered the home leg via the aptly named “homing” phase, which involved ATV-5 moving from her S1 waypoint at 30km from the ISS, to the S2 waypoint at 3.5km from the ISS.

The S-1/2 maneuver took place at 09:22:00 UTC.

The homing phase consisted of two 2m/s homing burns, and two 0.5m/s correction burns.

ATV RNDZ and Docking plan, via L2After ATV-5 arrived at the S2 waypoint, the “closing” phase was initiated, which took the vehicle from the S2 waypoint at 3.5km from ISS to the S3 waypoint at 250m from ISS.

This phase involved two 1.5m/s closing burns, and two 0.5m/s correction burns.

At the conclusion of these maneuvers, the Final Approach 1 (FA1) phase began, which took ATV-5 from the S3 waypoint at 250m from ISS, to the S4 waypoint at 20m from ISS.

After arriving at the S4 waypoint, ATV-5 aligned herself with the SM Aft port, untilizing relative guidance, whereupon FA2 began. This took ATV-5 from S4 at 20m to S41 at 12m from ISS.

linktoarticleplease2The approach was constantly monitored – but not controlled – by the crew inside the ISS, until the Crew Hands Off Point (CHOP) was reached when ATV-5 was one meter from the ISS. At this point ATV-5’s own momentum made any propulsive abort ineffective.

(ATV-3 Docking Animation created from 70 hi res ATV-3 docking images acquired by L2 – LINK).

Shortly following CHOP, contact and capture was confirmed via ATV-5’s adjoining via the Russian docking probe, which was retracted following shortly thereafter.

This led to the confirmation of a hard dock between ATV-5 and the ISS – confirmed at 13:30 UTC.

2014-08-12 02_20_59-Space in Images - 2014 - 08 - ATV-5 passes under ISSAhead of her arrival at the Station, ATV-5 was involved in an advanced sensor test, On 8 August, ATV-5 performed a ‘flyunder’ of the Station, passing 8 km below to gather video footage with special cameras installed on its front cone.

This test is designed to improve the capability of spacecraft when dealing with “uncooperative” targets, such as orbiting debris or a Mars sample capsule.

The LIRIS demonstrator – short for Laser InfraRed Imaging Sensors – was used to scan targets on the outside of the ISS, while onboard computers processed the data using new guidance navigation and control software. The results were recorded by hardware inside the pressurized element of the ship.

LIRIS was turned on for docking, but it was used in record-mode only, collecting additional data for later analysis.

2014-08-12 02_23_29-ATV-5 cargo - Google SearchATV-5 is delivering a large load of both internal (dry) and propellant (wet) cargo. Specifically, the pressurized Integrated Cargo Carrier (ICC) section is bringing around 2,600kg of cargo, including food, crew provisions, and scientific hardware to the orbital outpost.

The Service Module (SM) is carrying 570kg of water, 100kg of gas (air and oxygen), 2,230kg of propellants available for ISS reboosts, and 860kg of propellants for transfer to the Russian Segment (RS).

In addition to her manifest of cargo, ATV-5 will also serve as a “propulsion module” while attached to the ISS, aiding in attitude maneuvers, reboosts, and Debris Avoidance Maneuvers (DAMs) – all via the utilization of her Orbit Correction System (OCS) engines.

2014-08-12 02_24_11-ATV OCS - Google SearchUpcoming milestones are listed as involving pre-scrubbing, initial ingress tasks on Thursday, followed by final ingress and the test of OCS ATV reboost capability on Friday. A reboost is currently scheduled for August 27.

Following the conclusion of her Attached Phase Operations (APO), ATV-5 will undock from the ISS for a final time, prior to a destructive re-entry over the South Pacific Ocean. This will mark the conclusion of Europe’s heavy hauler cargo spacecraft’s role with the ISS.

ATV propulsion hardware will live on via its use on NASA’s Orion spacecraft, following a deal between ESA and the US Space Agency.

(Images: Via ESA, NASA, and L2).

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