The U.S. space program is about to go through some dramatic changes.  President Barack Obama has moved ahead with plans to retire the Space Shuttle in 2011.  U.S. missions to the International Space Station will be provided by Russia's aging Soyuz modular spacecraft.

Meanwhile, the U.S. government will work to fill its manned spacecraft needs with more permanent replacements from private sector companies like SpaceX and will fill in the gaps with NASA technology.  On Tuesday, NASA made a critical step forward to filling one of those gaps, completing a successful test of its DM-2 solid-fuel heavy-lift rocket.

Some may recall that NASA was contracting Lockheed Martin to develop a Shuttle successor named the Crew Exploration Vehicle, later renamed to the Orion.  That project was slated for cancellation by President Obama in February 2010.  The administration later recanted somewhat on that order, and in April decided to repurpose the Orion design for use as a rescue vehicle for the ISS.

Of course something needs to blast Orion into orbit.  That's where NASA's heavy-lift rocket comes in.  The five stage rocket is a marvel of engineering and is the largest solid-fuel rocket in history.  It can output 22 million horsepower and generate as much as 3.6 million pounds of thrust.  

The design is the result of a collaboration between NASA and an aerospace contractor, Alliant Techsystems' (ATK) subsidiary ATK Space Systems.  The test was carried out amidst a desert backdrop in ATK Space Systems' home state of Utah.

Aside from the brand-new fifth segment that helps the rocket set power records, the rocket also features other significant improvements from past designs.  It includes a modified nozzle throat and upgraded insulated liner.  These refinements make the rocket safer and more efficient.

The first test was a resounding success.  All segments of the rocket successfully fired at full power.  Better yet, they did so after being chilled to 40 degrees Fahrenheit, simulating cold weather conditions from likely launch locations like Cape Canaveral, Florida.

The rocket isn't slated to see action until 2015, so the program is well ahead schedule and has plenty of time for additional testing and fine tuning.  

Andy Schorr, first stage, five-segment motor lead for Ares Projects at NASA's Marshall Space Flight Center in Huntsville, Alabama comments, "The successful DM-1 test provided our team with great results.  All performance measurements were within specified limits and 46 total objectives, covering each significant design feature of the motor, were met."

"Our team is responsible for developing a robust propulsion system that can provide the thrust necessary to escape Earth's gravitational well and safely deliver astronaut crews and payloads to the International Space Station and beyond.  As we press forward, our goal is to optimize every aspect of the system for peak performance." 

Some haven't been impressed by NASA's recent direction, though.  Rob Zubrin, President of the Mars society in April lambasted President Obama's space vision, commenting:

Under the Obama plan, NASA will spend $100 billion on human spaceflight over the next 10 years in order to accomplish nothing"

Obama called for sending a crew to a near Earth asteroid by 2025. ... Had Obama not canceled the Ares 5, we could have used it to perform an asteroid mission by 2016. But the President, while calling for such a flight, actually is terminating the programs that would make it possible."

With current in-space propulsion technology, we can do a round-trip mission to a near-Earth asteroid or a one-way transit to Mars in six months ... Holdren claims that he wants to develop a new electrically powered space thruster to speed up such trips. But without gigantic space nuclear power reactors to provide them with juice, such thrusters are useless, and the administration has no intention of developing such reactors.

Despite the successful engine test, there's significant uncertainty, even with regards to the DM-2's purpose.  Initially the design was slated to carry a moon-lander called Altair for a mission by 2020.  Under Obama's new plan its left uncertain whether that mission will occur at all.  As there are no plans to currently fund a lunar push (the focus is instead on a Mars mission), it seems unlikely the DM-2 will every be put to this use, barring a change in direction by a future administration.

As an interesting side note, the DM-2 shares its name with the respectively diminutive Soviet Blok DM-2 rocket engine, designed in 1982.  That smaller engine has been used as recently as 2009, alone with Proton M, for GLONASS GPS satellite launches.