I agree with Bonk about FTL, but maybe not about genetic manipulation to endure the long flight. I'm not sure how much animals age when they hybernate. It may be possible to induce the same kind of hybernation in human beings, and allow them to "sleep" for hundreds of years. If a person did not age, living in an unconsious state at 3 degrees C, then it would just be a matter of keeping the spacecraft opperational until the crew is revived.
Where genetic modifacation would be required would be if we actually tried to colonize a planet with a biosphere. This would require an understanding of genetics at couple levels of magnitude than we currently understand. First, I have to explain why it is necessary:
Differences in gravity, atmospheric pressure, and the usual differences in planetary bodies would be miniscule compared to the differences in biological chemistry. Every biological process on this world is inter-related with just about every other biological process. Whether you dine on a piece of cow, or leaf of spinach, you are involved in a very ancient chemical relationship, just as your body provides a home to a vast number of different species.
Organic chemistry is very complex. There are a great many ways of doing the same thing. Subtle differences between compound constitute the difference between food, inert compounds, and poisons. This is not something like a human immune system would not be able to handle alien germs. Alien viruses are not likely to corrupt our DNA, but the very molecules they are made of are likely to be toxic, along with every bit of alien life and organic residue.
Since biology would not be compatable, either the biosphere of a planet would have to be stripped and reseeded, or humans would have to be adapted. Here, on Earth, most plants are made up of left handed molecules, while animals are made up of right hand molecules. This is the very deep level of chemistry that would have to be examined. To make a human out of alien chemistry would be nearly as extrodinary as life itself.
In any case, a lot of new technology would have to be created merely to understand what is out there. Building a robot to get a closer look at a distant world is at the outer edge of our technology. The impoverishment of Western governments will not allow the expendature on such a project. Perhaps the Chinese, with their totalitarian government, will do something for pure science and the future of mankind, but it's not bloody likely.