In science, the Uncertainty Principle says that you cannot precisely measure anything past a certain level ofprecision because the mere act of observing distorts the object of the measurement.
To do this the spacecraft will need fantastically accurate control systems: they will have to measure changes in the positions of the satellites with a precisionof 20 picometres (a picometre is a millionth of a micron).
The first and fundamental purpose was -- kind of goes unnoticed, but has a difficult -- the impact is difficult to measure with precision, but it was to provide badly needed relief to individual families who are devastated by this recession.