This paper discusses about the space communication challenges – especially deep space communications with a detailed analysis on channel coding techniques and modulation schemes. It explains about the free space loss (FSL) that occurs due to the presence of long distances (in terms of Astronomical Units) in AWGN channel with relation to the power transmitted and power received. Also, it discusses different kinds of digital modulation techniques employed in tandem with the algebraic channel coding schemes. The discussion in this paper is confined to algebraic coding schemes and probabilistic coding schemes, as such, are not give a detailed look. Convolutional - hard and soft, Hamming, Golay, Reed-Solomon are compared and their noise combat ability is discussed in detail using the help of... computer based simulations in MATLAB and SIMULINK. It is shown that low BERs can be achieved at very small Eb/N0?ratios using OQPSK, MSK, and GMSK techniques. Robust coding schemes for space communications are given an overview. All the codes and modulation schemes are compared and analyzed for an AWGN channel. Also an introduction to quantum communication is discussed with reference to coding schemes.