Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Century-Long Monitoring of Solar Irradiance and Earth's Albedo Using a
  Stable Scattering Target in Space   An inert sphere of a few meters diameter, placed in a special stable
geosynchronous orbit in perpetuo, can be used for a variety of scientific
experiments. Ground-based observations of such a sphere, "GeoSphere", can
resolve very difficult problems in measuring the long-term solar irradiance.
GeoSphere measurements will also help us understand the evolution of Earth's
albedo and climate over at least the next century.

1
The categories of this paper are: cs
4
The categories of this paper are: cond-mat
19
The categories of this paper are: eess
25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an
29
The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
12
The categories of this paper are: nucl-th
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
11
The categories of this paper are: hep-lat
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg