EVA-9 success as EAS is jettisoned – ISS reboost

by Chris Bergin

NASA astronaut Clay Anderson, on the end of the International Space Station (ISS) robotic arm, dramatically shouted “Jettison!” – as he pushed 1400 lb Early Ammonia Servicer (EAS) into the blackness of space.

The surreal sight was part of EVA-9, a successful 7 hour and 41 minute spacewalk conducted by Expedition 15’s Anderson and Fyodor Yurchikhin. A free video of the jettison is available on the link below (read more).

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**Images from the EVA**

**Free video of the EAS jettison**

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The EAS consists of two nitrogen tanks that provide compressed gaseous nitrogen to pressurize the ammonia tank and replenish it, as needed, in the thermal control subsystems of the Station. It also contains additional stocks of ammonia for American Early External Ammoniac Thermal Control System (EEATCS).

The 680kg tank was launched on STS-105 with Discovery in August, 2001 – and installed by astronauts Daniel Barry and Patrick Forrester during two spacewalks. It will eventually burn up in Earth’s atmosphere.

The official start time of the spacewalk was at 6:24am EDT, six minutes ahead of schedule. The total EVA duration (PET = Phase Elapsed Time) was 7 hours 41 minuted, and – according to ISS information – was the 88th spacewalk for ISS assembly and maintenance and the 60th from the station (28 from Shuttle, 38 from Quest, 22 from Pirs) totaling 357h 24m.

Following Monday’s EVA, a total of 97 spacewalkers (69 NASA astronauts, 20 Russians, and eight astronauts representing Japan-1, Canada-2, France-1, Germany-1 and Sweden-3) have logged a total of 544 hours 48 minutes outside the station on building, outfitting and servicing. It also was the 110th spacewalk by US astronauts.

‘Clay Anderson (EV1) and Fyodor Yurchikhin (EV2) successfully completed EVA-9 with A/L (Airlock) hatch closure at 2:05pm EDT, followed by cleanup and post-EVA ops,’ noted Monday’s On Orbit status report, available daily on L2.

‘Accomplished tasks of this spacewalk were (all times Eastern): Install a video stanchion at CP-7 (Camera Position 7) on the S0/P1 truss interface, from the VSSA (Video Stanchion Support Assembly). Reconfigure power connections at the SASA (S-band Antenna Support Assembly) on the S1 truss.

‘Remove and replace the failed RPCM (Remote Power Controller Module) S04B_F on the S0 truss which has impacted MT (Mobile Transporter) operations, and return old RPCM to A/L (Airlock).

‘Install an APFR (Articulated Portable Foot Restraint) on the SSRMS (Space Station Remote Manipulator System). EV1 ingress APFR, maneuver to jettison position & jettison the integrated VSSA FSE (Flight Support Equipment) and EFRAM (EVA Flight-Releasable Attachment Mechanism), with a combined mass of ~212 lb, in retrograde direction [done at ~9:19am].

‘Jettison the ~1400 lb Early Ammonia Servicer (EAS) [done at ~10:36am]. Perform CBM (Common Berthing Mechanism) seal cleaning at Node nadir port (for PMA-3 relocation in late August); and clean up, returning APFR to ESP-2 (External Stowage Platform 2) and ingress A/L [done at 2:05pm].’

Monday’s EVA-9 comes ahead of the arrival of shuttle Endeavour on STS-118 in just two weeks time. A number of get-ahead tasks were completed on the spacewalk.

‘As get-ahead Tasks, the crewmembers also removed GPS antenna #4, relocated an auxiliary bag from P6 to Z1, and released two fluid tray bolts on the Node Unity.’

The EVA was sandwiched inbetween two maneuvers by the ISS. The first was a maneuver on USTO (US-commanded RS Thrusters only) from +XVV (+X-axis in velocity vector) to –XVV, i.e. turning by ~180 degrees to fly backward, with 25P at the SM aft end flying forward, in readiness for conducting the EAS post-jettison avoidance reboost after the EVA, noted ISS information.

After the EVA-9 jettisoning of the EAS, ISS attitude control authority was handed over to Russian MCS (Motion Control System) thrusters for maneuvering to reboost attitude.

After the reboost firing, the station, at ~6:45pm Eastern, maneuvered to +XVV TEA (+X-Axis in Velocity Vector/Torque Equilibrium Attitude) and control authority was returned to US Momentum Management at ~7:30pm.

The next events on the ISS will be the undocking of the Progress resupply ship M-59/24P from DC1 Nadir, for reentry and burnup, ahead of the launch of Progress M-61/26P on August. The new Progress will dock at the vacated DC1 Nadir on August 5, two days ahead of the scheduled launch of shuttle Endeavour.

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