EAS to be jettisoned during STS-118 EVA

by Chris Bergin

The Early Ammonia Servicer (EAS) tank won’t be returned to Earth for re-fuelling. Instead it will be jettisoned off the P6 truss of the International Space Station (ISS) during STS-118’s mission, via a spacewalk – sources note.

While NASA have so far being unable to confirm or deny the information, it is understood the jettison will take place due to it obstructing the relocation of the truss segment it currently occupies.

L2, for expanded documents and insider information covering the space programs at work. To join L2, click the advert —>

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.

‘The purpose of the Early Ammonia Servicer is just to leave the station in a little bit better configuration than it is right now,’ said Forrester in his pre-mission profile on nasa.gov.

‘Ammonia is used as a coolant throughout the space station, and in the future, if we should develop a leak, the Early Ammonia Servicer provides the opportunity, once that leak is found and repaired, to re-service the system with ammonia.

‘This particular Ammonia Servicer will be used until such time as the ammonia is depleted, and it can be returned to Earth, re-serviced and brought back up on a later mission.’

STS-121 Mission T-Shirt. Use discount code ‘nasaspaceflight’ when ordering from Countdown Creations & receive 5% off!


The Servicer was to remain attached to the Station until a permanent system is activated on a future mission, or recycled on Earth before being returned later in the manifest.

However, the Space Station Remote Manipulator (SSRMS) – which will relocate P6 from Z1 to P5 – can’t handle the relocation with the EAS in place. Given there is no where else for the tank to go, it will be jettisoned overboard.

Due to the Alpha Joints on the next two arrays, the P6 wings have to stay rolled up after P3/P4 and S3/S4 arrive in its current location, so P6 is not generating power on Z1 after the 13A/STS-117 assembly mission.

STS-118 is currently manifested as the first flight for Endeavour since the Columbia disaster, with a NET (No Earlier Than) launch date of June 11, 2007, although that could move up to NET May 1, 2007.

Endeavour will be carrying out ISS assembly flight 13A.1, carrying S5 & Spacehab-SM & ESP3 to the station.

              LIVE UPDATE PAGES

Related Articles