Space agency chief Charles Bolden said the Space Launch System rocket will carry astronauts beyond Earth's orbit in the next decade to explore asteroids or the moon.  Critics in the U.S. Senate who had previously complained of delays in the rocket program, including Sen. Bill Nelson, D-Fla., flanked Bolden at the Capitol Hill announcement.  The rocket "will take American astronauts further into space than ever before," Bolden said. "Tomorrow's explorers will dream of one day walking on Mars."  The 30-story-tall rocket will rely on five space shuttle main engines, as well as strap-on boosters, to loft 77 tons of cargo into space. A later version of the rocket would lift 143 tons into orbit, surpassing the Saturn V.  The rocket's first manned launch from Florida's Kennedy Space Cener won't happen until 2021 and will cost several billion dollars a year more thereafter.  Hanging over the announcement was NASA's canceled Constellation rocket design, an ambitious effort starved of funding in the past decade. Nelson and other supporters of the rocket, such as Sen. Kay Bailey Hutchison, R-Texas, expressed confidence in Congress to fund the new rocket, despite a summer vote by a House committee to cut 9% from NASA's budget.  "At least now we have the White House and much of Congress pushing on the same direction on this rocket," said space budget expert Howard McCurdy of American University. "Will that be enough to save the other parts of NASA is the question."  NASA leaders said the rocket would provide employment boosts in states that are home to NASA centers, including Florida, Alabama and Maryland.  "The 2017 launch date is a hard deadline," regardless of ups and downs in NASA's budget, space agency official William Gerstenmaier said.  However, design work for the first manned launch, now targeted for 2021, could be pushed back if there are shortfalls in the rocket's funding. The first of a series of yearly launches aimed at an asteroid could happen around 2025.  "We do need a more crisp and clear answer for where NASA is going to go with the rocket, once they have it," said space policy expert John Logsdon of George Washington University in Washington, D.C. Given technological and budget realities, he said, "pretty clearly, we aren't going to Mars in the next 18 years."
The $18 billion Space Launch System will be the most powerful rocket since the moon race's Saturn V rockets.