The atmosphere is quite dusty, giving the Martian sky a light brown or orange-red color when seen from the surface; data from the Mars Exploration Rovers indicate that suspended dust particles of roughly 1.5 micrometres diameter.
Glutamate is a powerful excitatory neurotransmitter that is released by nerve cells in the brain. It is responsible for sending signals between nerve cells, and under normal conditions it plays an important role in learning and memory.
Glutamatergic system. Glutamate is the main excitatory neurotransmitter in the CNS. It is distributed so widely that it is impossible to talk about individual centres or projections. It plays an indispensable role in synaptic plasticity, i.e. the removal of old, unused synapses, potentiation of others and the formation of new synapses.