NASA?s test launch of a brand new rocket this week will last only minutes, but the space agency is expecting thousands of spectators to flock to its Florida launching site to watch the historic show.
The Ares I-X rocket, a suborbital prototype for a new booster designed to launch NASA?s planned shuttle replacement craft Orion, is slated to blast off Tuesday morning, weather permitting. But what exactly will the throngs of onlookers see at liftoff?
?It?s going to look pretty spectacular,? said Bob Ess, NASA?s Ares I-X project manager.
Standing at 327 feet (100 meters), Ares I-X is a towering rocket ? and currently the world?s tallest booster in service. Its $445 million test flight, which should last about two minutes, is poised to launch Tuesday at 8 a.m. EDT (1200 GMT) from Launch Pad 39B at NASA?s Kennedy Space Center in Florida.
It has been more than 30 years since NASA launched something other than a space shuttle to test a manned spaceflight system. NASA will broadcast the launch live on NASA TV, which will be webcast simultaneously.
For those spectators in the area of the Kennedy Space Center on central Florida?s eastern coast, the test launch should be viewable for miles around. The Kennedy Space Center Visitor?s Complex is selling tickets but other venues are available, much like during shuttle launches.
Just don?t expect Ares I-X to blast off like a shuttle. For one thing, it will roar off the pad a bit faster than a space shuttle, Ess said.
A fast blast off
When NASA shuttles liftoff, they actually ignite their three main engines six seconds early to begin building up thrust before the countdown clock hits zero. After those six seconds, a shuttle?s twin solid rocket boosters ignite, explosive bolts holding the spacecraft down are severed and the entire stack soars spaceward.
The gleaming white Ares I-X, at its core, is a giant solid rocket booster. As a prototype for the two-stage Ares I rocket, its first stage is a four-segment solid rocket motor capped with a dummy fifth segment. The second stage, Orion capsule and launch abort tower atop Ares I-X are all dummy segments, too. There is a 1-in-10,000 chance of a disastrous failure during the test, but NASA is confident it will go as planned.
So when the clock hits zero, there will be no six-second build up or giant plumes of steam from the water sound suppression system like those seen during shuttle launches. The explosive hold-down bolts will fire and the rocket should simply zoom off the pad, mission managers said.
?It?ll get up and go a bit faster than the shuttle does,? said Ares I-X launch director Ed Mango.
An odd white rocket
Unlike recent shuttle launches to the International Space Station, which head northeast after liftoff, Ares I-X will head due east out over the Atlantic Ocean. The rocket is long and slender, and fatter on top because its second stage is thicker than its solid rocket motor-powered first stage.
That means it will look weird, Ess said.
?I think, being long and thin and slender, optically it will look very strange coming across,? Ess said, adding that the first visible thing should be the standard roll program to orient the rocket. ?You?ll see the whole vehicle turn around by itself and then just kind of head due east ? I think it will move pretty quickly.?
There are 700 sensors on the Ares I-X rocket to measure things like vibration, speed, performance and other data. Mission designers have added little tweaks to the flight profile to move the rocket?s motor nozzle slightly in order to measure its effect on the booster.
?It probably won?t be visible to you,? Ess told reporters.
Clear skies vital for viewing
NASA needs good weather to launch Ares I-X because engineers need to see the rocket flight all the way through first stage separation, which will mark the end of the test.
That staging point is expected to come at about the 124-second mark, when the supersonic Ares I-X rocket is traveling Mach 4.7 ? more than four times the speed of sound, its max speed for the flight. The rocket stages should separate at an altitude of about 130,000 feet (24.6 miles or 39 km) and continue upwards until they hit a maximum altitude of 150,000 feet (28 miles or 45 km).
?Once separation occurs, that?s really the end of the launch trajectory,? said Doug Cooke, associate administrator of NASA?s exploration program.
Observers at NASA?s Kennedy Space Center and nearby viewing areas around the region, like the banks of the Banana River, may get a glimpse of stage separation. But only if the weather is clear. Ares I-X will be a bit farther away than a launching shuttle, Ess said.
?I think you may be able to see something happen in the sky, two white dots instead of one white dot. But I don?t think it?s going to be very clear,? Ess said, adding that television camera views should be better. ?If we have any cloud cover, it?s going to be difficult.?
The Ares I-X dummy second stage is expected to crash into the ocean about 147 miles (236 km) east of the launch pad. The first stage, however, is equipped with parachutes and designed to splash down in the ocean ? much like shuttle rocket boosters ? to be retrieved by a recovery ship.
A report released last week by an independent panel appointed by the White House to review NASA?s human spaceflight plans suggested that President Barack Obama and the space agency consider scrubbing the Ares I and pursue commercial rocket boosters instead. But Mango said the data gleaned from the test flight and its preparation will be vital, even though the Ares I rocket?s ultimate fate is uncertain.
?Even getting to this point, the team has learned about getting a vehicle designed and ready to be launched,? Mango said. ?It?s really an inspiring point to be at.?
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SPACE.com will provide full coverage of NASA's Ares I-X test flight with Staff Writer Clara Moskowitz in Cape Canaveral, Fla., and Managing Editor Tariq Malik in New York. Click here for full mission coverage.