A Russian space telescope set to launch on Monday will be the biggest ever, a feat that perhaps makes up for the fact that it has taken more than 30 years to develop.
The RadioAstron, which was first conceived during the Cold War, only has a 10-meter antenna, which is tiny compared to the 100-meter-long antennas on Earth’s largest radio telescopes. But combining the RadioAstron’s signals with those of earthbound telescopes in a process called interferometry creates images that are as sharp as those produced by a single satellite whose dish was as wide as the distance between the space telescope and its partner on Earth.
The RadioAstron will be launched to a distance almost as far away as the moon, creating a “dish” that, in effect, will be 30 times the Earth’s diameter. The resolution of its images will be 10,000 times that of images by the Hubble Space Telescope. If that isn’t mind-boggling enough, to put it another way, its images will be exact down to angles of just seven microarcseconds, which is 0.000000001944 of a degree.
Inferometry has been used to make Earth-sized radio telescopes for the last few decades. The first space telescope dedicated to radio interferometry, HALCA, was launched by the Japanese Space Agency in 1997. Images by RadioAstron will have ten times greater resolution because its orbit will be ten times as far from Earth.
RadioAstron’s applications
RadioAstron will aim its sights on objects such as the nearby galaxy M87, which has a gargantuan black hole at its core. The satellite may get images from near the black hole’s event horizon, which is the boundary around which nothing can escape the black hole’s gravity.
The telescope will also look at the microwave radiation given off by water masers, which are clouds of water molecules in the discs of galaxies. Such data could help determine the rotation rate of galaxies and determine their distance from Earth.
Combining that data with data on the speed at which galaxies are moving can help with another calculation: how quickly space is expanding right now.
The telescope will also look at pulsars, which are the remains of exploded stars, and the lighthouse-like radio waves they emit, in order to understand how dust and gas are distributed around them.
Too much data, too few receivers
After spending decades in development, the RadioAstron is finally set to launch from Kazakhstan’s Baikonur cosmodrome on Monday.
However, there’s one hopefully temporary hiccup: the amount of data will be enormous — about 144 megabits per second — but right now, only one antenna (in Pushchina, Russia, south of Moscow) will be collecting signals from the spacecraft.
Until other receiver stations are established, a lot of the telescope’s data will be lost. But RadioAstron’s team is working on setting up other receiver stations. Let’s hope it doesn’t take them another 30 years.
Photo: Hubble Telescope by NASA Godard Space Center
via: New Scientist
