Wednesday, November 14, 2007

Gigantic Delta 4-Heavy Blasts Off

On Saturday night, the largest US rocket blasted off, carrying a 2.3 tonne Defense Support Program satellite into orbit. This was the second time a Delta IV-Heavy rocket has ever lifted off. With three core boosters strapped together, it's like three rockets launched at once.

The launch was made even more spectacular because it was held at night. Launched at 0150 GMT Sunday (20:50 EST on Saturday), the 70-metre tall (230 feet) rocket has three separate engines, each of which can generate more than 2,900 kiloNewtons (650,000 pounds) of force. They guzzle a tonne of propellant every second.

On board the rocket was the Defense Support Program 23 spacecraft; the last in a program of Earth observation satellites designed to spot enemy missile launches and nuclear explosions.

Although the Delta IV-Heavy can carry 13 tonnes into a geostationary transfer orbit, it's not a commercial provider - just military and government satellites. Europe's Ariane 5 ECA is the most powerful commercial provider, able to blast off with 10 tonnes.

The Delta IV-Heavy first flew back in 2004. Boeing had originally proposed it as the vehicle that could carry the next wave of space exploration vehicles into orbit. In the end, though, NASA decided to go with the new Ares vehicle for its post-shuttle program.

During that previous test flight, the Heavy encountered a problem with its fuel lines, which caused the engines to go out early, and left the rocket lower than its intended orbit.

Just to put the capabilities of the rocket in perspective, though, the Saturn 5 could put out three times the thrust.

Oops, That Isn't an Asteroid, it's Rosetta

ESA's Rosetta was inbound to make a flyby of the Earth on November 13th? Well, another group of astronomers were watching this "unknown" object, and thought that it was actually an asteroid that was going to be making a close flyby of our planet. The astronomers realized their mistake, but not after an alert was sent out to the astronomical community. Oops.

The alert was sent out by the Minor Planet Center, a clearinghouse of asteroid information organized by the Smithsonian Astrophysical Observatory for the International Astronomical Union.

Astronomers had been tracking the approaching object, designated 2007 VN84. After many observations from astronomers around the world, they calculated that it would pass us by at a distance of 1.89 radii (from the middle of the Earth).

It would have been huge news, but Denis Denisenko from Moscow's Space Research Institute (IKI) realized that its flight path perfectly matched the upcoming Rosetta flyby.

Here's a link to an animation, captured by astronomers in Germany, of Rosetta inbound to the Earth.

And so, just to set the record straight, ESA's Rosetta spacecraft made its flyby on Tuesday, November 13th at 20:57 GMT, passing just 5,301 km above the Pacific Ocean. This has given it the gravitational boost it needs to meet up with Comet Churyumov-Gerasimenko in 2014.