Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Study of Dust and Gas at Mars from Comet C/2013 A1 (Siding Spring)   Although the nucleus of comet C/2013 A1 (Siding Spring) will safely pass Mars
in October 2014, the dust in the coma and tail will more closely approach the
planet. Using a dynamical model of comet dust, we estimate the impact fluence.
Based on our nominal model no impacts are expected at Mars. Relaxing our
nominal model's parameters, the fluence is no greater than ~10^-7 grains/m^2
for grain radii larger than 10 {\mu}m. Mars orbiting spacecraft are unlikely to
be impacted by large dust grains, but Mars may receive as many as ~10^7 grains,
or ~100 kg of total dust. We also estimate the flux of impacting gas molecules
commonly observed in comet comae.

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The categories of this paper are: dg-ga
8
The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat
0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
18
The categories of this paper are: econ
13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
36
The categories of this paper are: cmp-lg
32
The categories of this paper are: atom-ph
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex