White Paper: Focus on aerospace

Innovative Sensor Technology IST AG Temperature Sensors in Deep Space

First steps in outer space

Since German scientists made the first steps exploring space more than 70 years ago the interest and curiosity of further exploration and experimentation has been continuous. Since then, the first photos of Earth were taken, the first animal survivability tests were made and the first orbital launch was successfully accomplished by the Soviet unmanned Sputnik 1.

On 12 April 1961, the first successful human spaceflight Vostok 1 (“East 1”), carrying 27 year old Russian cosmonaut Yuri Gagarin, completed an orbit around the globe lasting about 1 hour and 48 minutes. Since then, many nations have been involved in the further exploration of space including the first planetary explorations.

Being one of the leading sensor manufacturers on the market, Innovative Sensor Technology IST AG early on established a role in the aerospace industry because of the many demands and qualifications needed to operate in space.

Sensors on a space mission

The Rosetta space craft was launched more than ten years ago by the European Space Agency with the purpose of performing a detailed study of the comet 67P/Churyumov-Ger-Copyright: ©ESA–C. Carreau asimenko. After reaching and orbiting the comet in August 2014, the lander of the mission, Philae, is expected to launch in November 2014 and complete the mission. The space craft itself launched over a decade ago, but the beginning of the project dates back a lot further. During this period of time, it is estimated that over 2000 people from all over Europe have worked on this project and its sub-projects. One of those is the instrument Rosina, which is a spectrometer for ion and neutral analysis. Innovative Sensor Technology IST AG was approached by EMPA, who built two critical parts for this project. IST AG was asked to develop three individual, ultra-thin temperature sensors specifically customized for the application. “The requirements for the sensors include a high accuracy, longterm stability, as well as suitability for harsh environments”, says Dr. Jiri Holoubek, Chief Technical Officer at IST AG and responsible for the project at IST AG since the beginning.

Another customer specific temperature/heater-multiparameter-sensor was developed for Tesat-Spacecom. The earth-monitoring satellite Sentinel-1A, launched in April 2014, as well as the European communications satellite Alphasat, launched in July 2013, are equipped with a laser communications terminal (LCT), developed and produced by Tesat. The IST AG multi-parameter-sensor ensures an accurate temperature of the LCT laser crystals. The terminal serves as a preparation for the European data relays transmission system (EDRS) and demonstrates a very high transmission rate (about 3 DVDs per minute) between the Low Earth Orbit (LEO) and the Geostationary Earth Orbit (GEO) and thereby significantly improves earth monitoring applications.

The use of IST AG platinum temperature sensors is also planned for future space missions. In 2017, a satellite for the exploration of the sun is supposed to be launched into space. The satellite is supposed to approach the sun as no space craft before. The main goal is research of the solar winds, the so called space weather. Doing so, the satellite will record structures in the suns corona up to a distance of 35 km. The issions duration is expected to be seven years.

An additional satellite project, in which IST AG’s Pts are used, is a new space telescope. The expected start is scheduled for 2020. The purpose of the project is the re-measurement of the universe and its depths as well as solving the phenomenon of dark matter and dark energy.

Possibilities of thin-film-technology

IST AG sensors are used for measurements in various applications. Depending on the application, temperatures between -200°C and +200°C are applied for active temperature control of the outer shell or of measurement instruments inside the satellite.

Temperature control is becoming increasingly important and critical for missions in outer space. Therefore, the previously often used wire wound platinum temperature sensors, which shaped the last decades, are now being used less and less in satellite projects. The pure temperature measurement is being replaced by active temperature regulation. With a failure rate of up to 20% for monitoring, active regulation does not allow for failures anymore.

Wire wound platinum sensors, which are very thin wires wounded over a ceramic plate, are very vulnerable to vibration as well as thermic cycles and have a high failure rate. When it comes to thin-film-technology, one of IST AGs core competences, the resistive platinum structure is deposited directly to the ceramic surface of the sensor, making the sensors highly suitable for applications with higher vibrations.

Currently, there are no EAS/ESCC qualified Pt wire wound or thin-film temperature sensors on the market. Due to industrial experience and the comprehensive participation in many satellite projects, IST AG has been able to proof the reliability of their sensors. In order to qualify the sensors easier and save time in the process, IST AG has joint forces with ESA. The main goal of the cooperation is to provide ESCC qualified sensors which can be used in every ESA mission.

Due to the ESCC qualification, the “Lot Validation Tests“ (LVT) do not have to be performed for every customer order in the future. Through a survey, various customer requirements have been evaluated and taken into account during the development. The objective of the qualification is to offer standardized sensors available from stock, and there through, reduce delivery time immensely.

IST AG sensors - robust and accurate

Innovative Sensor Technology IST AG thin-film sensors are highly suitable for applications in satellites. Weight and size, compared to wire wound sensors, can be reduced significantly. Even high resistive values (up to 2000 Ω) are available on a sensor chip measuring 2 x 2.3 mm in size. Furthermore, for many European organizations and companies, it is of high importance, that the products are manufactured in a European country. This guarantees the availability of the sensors and simultaneously the risk of export restrictions can be avoided.

Part of IST AGs successful strategy is the diversification in various challenging markets. The technology of the sensor specialist is perfected to a degree, where even applications with the highest of quality demands are covered. This offers IST AGs customers a whole new array of applications possibilities.