Sounds like pretty new terms? They are all about NASA’s next space program. The Constellation program is simply what is also called the “Vision for Space Exploration“.
In short, it means that new launchers and crew vehicles will be developed to ferry people to the international space station ISS, later on to the moon and even later to Mars. Ares is what the launchers are being called. Ares I will be the rocket that launches humans into space while Ares V is a heavy-lift rocket used to launch the heavy equipment. Finally, Orion is the name of the new crew capsules, also known as “Crew Exploration Vehicle”.
It looks quite doable to return to the moon, but sending humans to Mars is much more challenging. A lot of work needs to be done to solve the issues. I am sure they can be solved if we try hard enough, but the question is if there will be budget allocated to do so.
The Constellation program borrows heavily both from the Apollo as well as the Space Shuttle programs. For example, the overall launcher and capsule design is based on Apollo. The shuttle program contributes its boosters. Some folks tend to say that Constellation becomes more and more an Apollo V2, especially as the budget is quite constrained. It is not yet clear how far resuable the Orion capsules will be.
In my blog, I write about Constellation, Ares and Orion. While it is quite early to know any specifics, it is an interesting time to watch development. If you are interested in a specific topic, just follow the relevant labels.