September 1, 2015

Innovative Sensor Technology Temperature Sensors in Deep Space

Since the early space explorations by German scientist more than 70 years ago, there is a rising demand for further exploration and experiments in this area. In the meantime, the first shots of Earth were taken, animals were sent into space for survival test and the first full circulation of our Planet by a satellite, the unmanned, soviet Sputnik 1, was conducted successfully.

On April 12th 1961, Juri Gargarin was the first human to travel into space. The then 17 year old Russian cosmonaut circled the Earth on the so called Wotstok 1 (East1) mission in one hour and 48 minutes. Since then, a lot of Nations were part of the exploration of space, including the first steps taken in space.

As one of the leading manufacturers of sensors and because of the many requirements and necessary qualifications needed for space applications, Innovative Sensor Technology IST AG has been involved in the aerospace industry from the get go.

Sensors on a space mission

The Rosetta space craft was launched more than ten year ago by the European Space Agency with the purpose of performing a detailed study of the comet 67P/Churyumov-Gerasimenko. 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 build 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, long-term 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 specifically constructed temperature/heater-multiparameter-sensor was developed for Tesat-Spacecom. The, in April 2014 launched, earth-monitoring satellite Sentinel-1A as well as the, in July 2013 launched, European communications satellite Alphasat are both equipped with a laser communications terminal (LCT), developed and produced by Tesat. In this LCT, the IST AG multiparameter-sensor takes care of an accurate temperature of the laser crystals. The terminal serves as a preparation for the European data relais transmission system (EDRS) and makes a very high transmission rate (about 3 DVDs per minute) between the Low Earth Orbit (LEO) and the Geostationary Earth Orbit (GEO) possible. With this, earth monitoring applications and services are supposed to be improved.

The usage of IST AG platinum temperature sensors is planned for future space missions. In 2017, a satellite for the exploration of the sun is supposed to be launched into space. It will get as close to the sun as no space craft before. The main goal is going to be the research of the solar wind, the so called space weather. Doing so, the satellite will record structures in the sun's corona up to a distance of 35 km. The mission's duration is expected to be seven years.

An additional satellite project, utilizing IST AG's Pts, is a new space telescope. The expected start is scheduled for 2020. Subject of this project is the remeasurement of the universe and it's depths as well as solving phenomenons regarding dark matter and dark energy.

Possibilities of thin-film-technology

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

The temperature control is becoming more important and critical for mission in outer space. Following this, the trusty wire wound platinum temperature sensors, which shaped the last decades, are 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 doesn’t 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, which is, as mentioned at the beginning, one of IST AG’s core competences, the platinum resistance structure is permanently connected to the ceramic surface of the sensor. Therefore the sensors are very much suitable for applications with higher vibrations.

Currently, there are no EAS/ESCC qualified platinum temperature sensors on the market, neither wire wound nor thin-film sensors. Following the years of experience in Industry and thanks to the participation in many satellite projects, IST AG was able to proof the reliability of their sensors. In order for customers to easily qualify the sensors and safe time in the process, IST AG is cooperating with ESA. The main goal of joint venture is to get ESCC qualified sensors to be used in every ESA mission.

Thanks to the ESCC qualification, the “Lot Validation Tests“(LVT) doesn’t have to be newly configured for every customer’s order. Through a survey, various customer requirements have been evaluated and were taken into account during development. The qualification’s goal is to offer standardized sensors, which leads to the availability of certain variations of said sensors at IST AG. Those can be then ordered from stock, which reduces delivery time immensely.

IST AG sensors, robust and accurate

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

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