So I thought it worth talking about what STP actually is. It is not really astronomy though it has long been grouped with it; it is not even space science in the sense of the words that STFC seems to use (which is more like space technology).
Solar Terrestrial Physics deals with the processes that drive the connection between the Sun and the Earth and the way in which the different regions of near-Earth space couple together. This makes it part meteorology (sort of) and part fundamental physics. The fundamentals arise in trying to understand the actual processes that underlie the sun-Earth interaction and the meteorology is our trying to understand what happens, when and where and the consequences for society.
On the fundamental level there are two big questions (I think):
- How does magnetic reconnection work?
- How are charged particles accelerated to relativistic energies?
Other questions include understanding how energy and momentum travel through the vertical atmosphere and ionosphere? what roles do turbulence play in space plasmas? does the magnetosphere exhibit emergent behaviour? etc.
Then we move into the meteorology aspects. We want to determine, exactly where and when electrons are accelerated. This is important both for protecting our technology in space, which is vulnerable to high energy charged particles and for applications on the ground. In particular in the polar regions where some communication systems can be wiped out by space weather effects. These could be vital safety-for-life applications!
We want to know where and how energy is deposited in our atmosphere and how it is transported. Why does reconnection occur at some points and times and not at others in the magnetosphere? This doesn't even cover the plasma experiments that can be performed in the ionosphere where boundaries are much less important than in plasma chambers.
Basically it comes down to expanding our knowledge of our near environment. Knowing how the world works and what effect that might have on us.
Where STP really differs from astronomy is the way in which we do it. Instead of relying on a couple of instruments (or even one) to study from afar. We use remote techniques as well as getting up close and personal, and we often use many instruments in conjunction to diagnose the plasma environment and put small scale observations into the larger context of the Earth's space environment. We use cameras with radars, magnetometers and riometers to look at the ionosphere and then link that with direct observations of the magnetospheric plasma from insitu satellite measurements. We use a large suite of instruments to do our science rather than single or a couple of measurements.
You may think that sounds expensive, but you can consider ground-based STP instruments as multiple instruments on a satellite with added advantages: they have a much longer lifetime, they are cheaper to build, they provide more than a snapshot in space. The soon-to-be closed ground-based facilities were UK led and gave us buy-in to other data sets around the world though collaborative agreements and membership (often leading) of international consortia. UK STP is world leading science. To make clear, this does not mean that satellites are unimportant, far from it, just that through combining the satellite measurements with the ground based observations we can build a clearer picture of what is happening and what we are seeing. Satellites alone can provide excellent science, but their worth is multiplied in conjunction with ground based facilities.
For considering costs let's take an example. The SAMNET magnetometer chain is run by Lancaster university to provide important information on the location and timing of large releases of energy into the ionosphere (amongst other things such as studies of high energy electron loss and mass loading of the inner magnetosphere). It is also the provider of data for AuroraWatch, an outreach programme that lets subscribers know when there is likely to be an auroral display that they can see. The cost of running SAMNET (with associated technicians) for one year is under £47,000. Whereas operations of a single satellite instrument can be over £450,000 per year.
However they are all going to go. Some of our facilities were cut a while back because "we did not make the case that our science was important". I wonder now whether it was less us not making the case and more an inability on other's part to comprehend the interdisciplinary and fundamentally different work that we do when compared to astronomy.
Note I am not blaming the astronomers here, if anything it is a system that fails to allow adequate representation on major decisions for a distinct field of physics, and that has been the way for quite some time.