By Joel Achenbach — More doable is a human mission that orbits Mars. Astronauts could essentially telecommute to work, operating rovers and other instruments from orbit. Indeed, a Mars orbit in the 2030s is an official NASA goal, direct from Obama. On April 15, 2010, in a closely watched speech at the Kennedy Space Center, the president said that by 2025, NASA will begin missions to "deep space," starting by "sending astronauts to an asteroid for the first time in history." Then would come a Mars orbital mission in the mid-2030s, he said.
"And a landing on Mars will follow," he said, without giving a certain date.
He added: "I understand that some believe that we should attempt a return to the surface of the moon first, as previously planned. But I just have to say pretty bluntly here: We've been there before."
Months after Obama's big speech, powerful senators from states with NASA centers and contractors took steps to salvage major chunks of the Constellation program. Congress directed NASA to continue building a heavy-lift rocket that could take payloads beyond LEO. Orion would also go forward.
The new rocket is called the Space Launch System, although the less reverential name for it in the space community is the Senate Launch System. It's being designed in Alabama and built in Louisiana, and will be tested in Mississippi before being launched in Florida and supervised by Mission Control in Texas. It has many supporters.
What the jumbo rocket and the Orion capsule can't do, without adding a lot of costly hardware, is fly to a distant asteroid that's orbiting the sun.
It's natural to envision spaceflight as a journey from point A to point B. But it's a lot more complicated than that, because points A and B are both moving, and at different speeds. Thus engineers rarely talk about distance, and instead talk about trajectories, orbital dynamics and "delta V." That's the change in velocity.