Smallest space telescope will look for ‘starquakes’

U. TORONTO (CAN) — The smallest astronomical satellite ever built, weighing less than 7 kilograms (15.5 pounds), launched Monday, February 25.

The nano-satellite—which was launched along with its twin—is part of the BRIght Target Explorer (BRITE) mission—an effort to design, assemble, and deploy small satellites quickly and relatively cheaply.


“A nano-satellite can take anywhere from six months to a few years to develop and test, but we typically aim for two years or less,” says Cordell Grant, Manager of Satellite Systems for the Space Flight Laboratory at the University of Toronto Institute for Aerospace Studies (UTIAS).

Up to now, such nano-satellites had been used only to monitor the earth and experiment with new technologies.

“Researchers, scientists, and companies worldwide, who have great ideas for space-borne experiments, but do not have the means to fund a large spacecraft, can now see their ideas realized,” says Grant. “BRITE has the potential to open an entirely new market for low-cost high-performance satellites.”

BRITE is the first nano-satellite mission intended for astronomy, and the first-ever astronomy constellation—more than one satellite working toward a common objective—of any size.

“BRITE is expected to demonstrate that nano-satellites are now capable of performance that was once thought impossible for such small spacecraft,” says Grant.

But only small telescopes can fit within a 20-centimeter (8-inch) cube. Therefore, BRITE is not intended to take pretty pictures, but will simply observe stars and record changes in their brightness over time.

Such changes could be caused by spots on the star, a planet or other star orbiting the star, or by oscillations and reverberations within the star itself—the analogue of earthquakes on stars. The study of these so-called “starquakes” is called asteroseismology.

To perform precise measurements of the brightness of stars, the telescopes need to be above the atmosphere. Otherwise, scintillation—the atmospheric effect that causes stars to twinkle—overwhelms the relatively small brightness variations of the stars themselves.

By avoiding this, a very small telescope in space can produce more accurate data than a much larger telescope on the ground. Also, unlike telescopes on Earth which are useless during the day, in bad weather or when the stars set below the horizon, telescopes in space can potentially observe stars all the time.

As their name suggests, the BRITE satellites will focus on the brightest stars in the sky including those that make up prominent constellations like Orion the Hunter. These stars are the same ones visible to the naked eye, even from city centers.

Because very large telescopes mostly observe very faint objects, the brightest stars are also some of the most poorly studied stars.

It turns out that the brightest stars are also the largest. Big bright stars lead short and violent lives and deaths (supernovas) and in the process seed the universe with heavy elements without which life on Earth would be impossible. To better understand these stars is to better understand how life arose on our planet.

Because big objects oscillate and quake slower than smaller ones, the BRITE satellites do not have to keep their eyes constantly on any given star, but can observe from time to time to see if anything has changed.

Hence, the BRITE satellites can monitor their target stars whatever orbit they are placed on, and do not require a dedicated rocket to place them in a specific orbit. By piggy-backing on any available rocket, the BRITE satellites can thus be launched for relatively little money: the first two BRITE satellites will be sent to space on the Polar Satellite Launch Vehicle (PSLV) C20.

To gather more observations and to increase the lifetime of the mission, scientists will be launching three such pairs of satellites—one Austrian pair, one Polish pair, and one Canadian pair supported by the Canadian Space Agency—so that within a few years BRITE will become a constellation of six satellites. Each twin in a pair watches the sky in a different color (red or blue), providing another exciting layer of data to the scientists.

Source: University of Toronto