First sentence of the paper:

> 1.INTRODUCTION For a vehicle travelling in empty space it’s momentum, as well as it’s energy, comes from it’s fuel.

His, hers, its - are all possessives.

This is why one should have papers for publication, a CV, or a résumé proofread by someone who can spell correctly and understands grammar. Spell-checking software is fine, but it will not catch everything. If it is important, read it aloud to yourself, then get a friend to read it aloud to you. Yes, here the intended meaning is obvious, but this left me wondering about the accuracy of the rest of the paper, which is not a good start for any reader of anything written.