Sensors ready for launch

Hamilton Bonaduz AG has recently completed a very exceptional project. The specially developed sensors VisiSpace for measuring dissolved oxygen as well as ConduSpace for measuring conductivity, are part of the new life support system ACLS (Advanced Closed Loop System) from Airbus.

The ACLS is an advanced life support system that has been developed by Airbus for the European Space Agency (ESA) since 2011 to be used as a technology demonstrator on the International Space Station ISS.

The module subsystems extract carbon dioxide from the cabin atmosphere, generate new oxygen and produce water. Methane is a by-product that is either  re-used or discarded.

Compared to existing modules, ACLS is unique in its compactness. Nevertheless, it produces about 40 percent of the fresh water that is needed for its own operation, thus significantly reducing the amount of water that needs to be transported to the ISS for the operation of the ACLS.

The VisiSpace sensors of Hamilton determine the dissolved oxygen concentration in the hydrogen supply line of the electrolyzer as well as in the carbon dioxide line of the CO2 adsorber to the so called Sabatier reactor. The conductivity sensor ConduSpace monitors the quality of the process water in the elctrolyzer. “In order to fulfill the special requirements in space, we have made some changes to our standard dissolved oxygen sensor VisiFerm DO”, explains Dr. Peter Schulthess, Project Leader Application Engineering at Hamilton Bonaduz AG. In particular, the sensors have to withstand by far higher forces acceleration and deliver precise measurement results in zero gravity. “The sensors have been thoroughly tested for their suitability in space and, among other things, accelerated up to 25 g, which is equivalent to 25 times of the earth’s gravity. The sensors resisted this acceleration without any problems“, states Schulthess. In comparison, astronauts are exposed to 4 g and travellers at flight manoeuvres in passenger aircrafts to 1.5 g. The delivered sensors also fulfilled vibration tests on all three axes as well as the highest requirements on their leak tightness. Due to the system’s compact design, the sensor’s height had to be reduced by means of a lateral connector and a flange attached to the shaft.

“The countdown for our sensors in the rocket to ISS starts soon:  The supply flight with the ACLS will launch a few minutes after midnight on September 11 from Japan to the ISS”, explains Dr. Schulthess. From the beginning of November, the German astronaut Alexander Gerst is scheduled to install the module and make it ready for operation. All installations and functional tests are scheduled to be completed by the end of this year, in order for ACLS to be ready to prove operational capability in 2019. Designed for a 3-men crew, the ACLS is supposed to prove its technical capabilities, before it could become a permanent subsystem of the ISS.

Information about the standard sensor VisiFerm DO can be download here https://www.hamiltoncompany.com/products/process-analytics/sensors/dissolved-oxygen/visiferm-do, information about Conducell 4USF can be download here https://www.hamiltoncompany.com/products/process-analytics/sensors/conductivity/conducell-4uxf.