6. Examples of semantic change in space data

Expected learning outcome for this Part Understanding the principles underlying PERICLES
Level of advancement of this Part Intermediate
Approximate time to complete this Part 8 min.

The most obvious changes occur in the modifications of the ground system during the course of operations: current formats for scientific data and data treatment software change and new versions exist.

More fundamental changes also appear during and after the mission; the scientific objective may change, a value which was first thought to be a constant could be found to be a variable, then series of this value and their variations become the main objective. Further,the time span and granulometry of the series might be different for scientists. A chemically neutral atmospheric gas as carbon tetrachloride could receive a new role as a greenhouse gas and move from a minor objective to a new priority. These changes that we do not know in advance are the ones that we can expect to interest the scientists of the future. The PERICLES objective is to enable the study of new science objectives at the time of data reuse. An example is shown in the three next slides for the SOLAR  package on the ISS, a set of instruments measuring  solar spectral irradiance at the earth’s orbit.

The students, if possible, should propose other series in earth and space sciences and consider them.