"Why send people?" is modded "Troll"? A bit offtopic maybe, but not "Troll". This is the question we must be able to answer if we are to have a successful manned space program, Constellation, DIRECT, COTS, or otherwise.

In the Apollo era, manned space flight provided another means to fund weapons development. The launch vehicles of the early space program, including the Saturn family, are variations of ballistic missiles or started development as heavy launch vehicles for DoD payloads. We are no longer in the same kind of arms race, and finding money to fund civil aerospace ventures is not as easy as military ones.

Many have tried to explain "why" manned space flight in general, let alone the moon and Mars (recently here and here). It is not an easy question to answer. Arguments to the contrary range from "robots are cheaper" to "we should stop spending money on space altogether and address the large number of problems we have here on Earth".

There are those that will say we should do it simply because it is there to explore. That it is human nature. Because it is the unknown, the "final frontier", if you will. A romantic notion (and one that is more than enough to convince some of us), but in the end, this is a political question. We must justify spending tax dollars on manned space flight. What's in it for the taxpayers? While some like to point to technologies that have been spun off of NASA's work over the years, it's not easy to say that the tax-paying public will get X, Y, and Z from future investments.

The true answer here is one that few, if any, politician would ever use even if they knew it was the answer. Why send people? So that we can to guarantee our survival as a species. Humanity has spread beyond the cradle of its birth for many reasons. Initially the exodus was to find more room and resources to support our growing species. Later it was from reasons ranging from natural disasters to religious disputes to dreams of fortune in other lands. If our entire species lived at the foot of a volcano, the volcano could wipe us all out. Our species has spread such that it cannot be wiped out by most natural (or even man-made) disasters. It is only recently that we have started thinking at a scale larger than our local area on this planet. There is plenty of evidence of mass extinctions throughout the Earth's history. Whether by internal (global climate change) or external (comet/asteroid) forces, we are essentially planted at the base of a cosmic volcano. It is time to move beyond the fertile cradle of humanity's birth to ensure its long-term survival. In the past it took picking up and moving to a new field or forest or across a desert or an ocean. These took a variety of effort and planning, but none compare to the journey ahead of us. Our vision as a species, recognizing our strengths and weaknesses and the environment that surrounds us, must guide these decisions for the future. We have taken the first steps to develop habitats for humans to live and work and experiment and learn outside of Earth's atmosphere. We now must take the next steps to develop habitats and technologies that allow us to survive in even harsher environments...those on other planetary bodies. The moon is the closest, and perhaps one of the harshest, places for us to start to take these steps. Without this step, we cannot make the more important steps of leaving our orbit for others around the sun, and someday to other solar systems. We will most definitely not see the results in our lifetimes, but we need to be at a place where our short individual lives don't dictate every decision we make as a species.

Most people alive today can name Armstrong and Aldrin (and some even Collins...though sadly not enough). How many know the names of Cernan, Evans, and Schmitt? Or can name the most recent shuttle or ISS crew members? While I'm sure this community boasts some who can, it is a small minority of the public. The vision has always been to get "there". To orbit...to the moon...but that is where it ends. Repeating the feat soon becomes "ordinary", with only Apollo 13/Challenger/Columbia disasters grabbing the public's attention, and soon leads to cancellation and cutting of funds. We are not good as an agency of publicizing our accomplishments or getting public support behind a longer term vision. Waving beautiful images of planets or galaxies, shiny spinoff technologies, or fantastic engineering accomplishments (Apollo) will only get us so far. Robotic exploration, or even a direct manned shot to Mars like we did with the Apollo program to the moon, may give us great satisfaction and prove that we can accomplish great things. But no matter how great the accomplishments of the Apollo program, we did not build off of them with a vision for a grander goal. We must have a vision and a plan, and continue to work in that direction until we are no longer at a single point of failure as a species. I do not know how, or even if, it will be justified to the American public (or that of the world) in my lifetime. I just hope we can begin that journey, and sustain it to a successful conclusion.