Tag Archives: MEO

an error during test to your advantage

Everybody knows the Monopoly card  “a failure of the bank to your advantage, you receive…..”

An error that occurred during the vibration testing of our BiSon74-ET-RH sensors feels a bit like that.

Although the sensors were programmed to be tested to very significant levels (1g^2/Hz totalling 38.9g) it has now been confirmed that there was an error in the piloting channel that led to much higher test levels (as can be seen in the accompanying graph.

This plot (taken by the control accelerometer in Y axis) shows an integrated level of 58.77g and a spectral density which is more like 2g^2/Hz.

Although we would never have asked for such high levels of testing ourselves, it feels like an advantage to have done so, knowing that the sensors have survived.

Even THOR did not damage or senSOR

Today we finished pyroshock testing at the ISISpace THOR facility. THOR stands for Testing Hammer for extraOrdinary Rough environments. These tests were performed in frame of an ARTES 5.2 program called ITAR free extended temperature sunsensor.

3 BiSon74ET-RH sensors with two different builds were tested. These sensors went through thermal cycling and vibration testing before. In frame of this program the sensors saw 12 thermal cycles from more than +125C to less than -125C, followed by 30g sine and 40.2g random vibration tests. (al at ESTEC)

Today the test sequence was completed by administering 3 shocks of 3500g in all three directions.

Next to the BiSon74-ET-RH, the same test tests were also performed on two BiSon64 units to validate the latest configuration

As electrical tests showed that non of the units lost functionality and there was some time left in the program, ISIS agreed in doing some additional tests. This lead to a second set of tests performed on three sunsensors (1 from each batch of BiSon74-ET-RH sensors and one BiSon64) in which another 3 shocks in all three directions was administered but this time at 10.000g.

BiSon74-ET-RH Engineering models received

Designed in frame of the Artes 5.2 program ITAR free extended temperature fine sunsensor and intended to be the first small fine sunsensor to be capable of surviving the temperature excursions and radiation exposure experienced when mounted on extendable solar panels of geostationary telecom satellites, The BiSon74-ET-RH is intended to be a unique sensor, providing a cost effective and highly reliable solution to some issues already known for years.

Fine sun sensor - BiSon74-ET-RH Engineering model (ITAR free, extended temperature)

BiSon74-ET-RH Engineering model

In stowed configuration, solar panels quite often obscure the field of view of sunsensors thus hampering effective attitude acquisition during the Launch and Early Orbit Phase (LEOP) of many missions. Mounting a sunsensor on the solar panel until now was not feasible because no generally available sunsensor could handle the temperature ranges associated with this application. In Safe mode operation, the reliability of the solution is of utmost importance, and adding a sunsensor to the solar panel is the most direct and reliable way to measure the orientation of the solar panel. This is why Lens R&D (with support of ESA) is developing and qualifying an extended temperature sunsensor who’s temperature range allows for application at even the most demanding positions on a satellite, be it thin mechanical brackets or solar panels.