  Altermagnets are a new class of magnetic materials, which exhibit large spin
splitting, but due to the combined spin and real space group symmetry
protection maintain zero net macroscopic magnetization. Such a characteristic
may prove them to be superior in applications in superconducting
heterostructures and thus here we investigate the Andreev reflection at the
altermagnet/superconductor interface. We compare and contrast altermagnets to
other magnetic materials, revealing qualitative differences in the behavior of
altermagnetic junction depending on the Fermi surface orientation. We study the
resonant states arising in setups with strong tunneling barriers and show that
sensitivity to non-magnetic disorder is also dependent on the orientation. Our
results provide a building block for altermagnetic superconducting
heterostructures such as Josephson $\pi$ junctions with superior properties.
