Published in The Patriot Ledger August 23, 2014
In the 1950s and 1960s, it was the Soviets who had most of the space firsts, including the first satellite, first man in space, and first rocket to the moon. Starting with the Apollo moon landing in 1969, it has been NASA that has had the most space firsts. But earlier this month, the European Space Agency (ESA) scored a major space first when its Rosetta spacecraft rendezvoused with a comet.
Among the various reasons that comets are of interest is that many comets are believed to have crashed into the young Earth roughly four billion years ago, thereby delivering water that we think was important to the origin of life on our planet. Along with the water, they also delivered various organic compounds that are among the building blocks of life. Rosetta’s rendezvous and subsequent extended study of a comet will provide more detail on the early days of our solar system and on the mystery of how life originated on Earth.
The ESA spacecraft Rosetta, named after the famous Rosetta Stone that helped us crack the code of ancient Egyptian hieroglyphics, finally reached Comet 67P after a 4-billion-mile trip through space. It has now started traveling along with the comet, at a speed of over 35,000 miles per hour, for over a year of intense study. Currently about 60 miles from the comet, it will later drop to a closer orbit and, if all goes well, will release a lander to the comet surface in November. Rosetta and its lander carry a bevy of scientific instruments that will enable it to characterize a comet in much greater detail than any previous studies.
Rosetta was launched in 2004 on an Ariane rocket from the ESA’s launch site in French Guiana, the proximity to the Equator providing an extra push from the rotation of the Earth. In the past ten years, Rosetta has orbited the sun five times, gained extra speed from close flybys of Earth and Mars, and photographed two asteroids as it flew through the asteroid zone. Its electronics were put into hibernation mode in January 2001 but reawakened this past January to enable it to use its thrusters to maneuver close to 67P.
Comets are a mixture of stone and ice that orbit the sun in elongated elliptical orbits. (Traditionally named after the astronomers that discovered them, this comet is officially known as 67P/Churyumov-Gerasimensk, but to save ink let’s just keep calling it 67P.) A few comets produce bright tails that are visible by naked eye from Earth, but 67P, like most, will be visible from Earth only by telescope – and now by close-up photos sent back by Rosetta.
The comet, about 2 miles across, is currently emitting water at a modest rate of about a quart a second. But 67P will warm as it approaches the sun in the coming months, and this emission rate of water is expected to increase by factors of thousands, breaking off many particles of stone and creating a tail up to a million miles long. And Rosetta will be there to record all this in great detail, an important space first.
NASA has not ignored comets. Its spacecraft Deep Impact flew by a comet in 2005, analyzed its chemistry from a distance, and launched an impactor that crashed into the comet, providing experience for the day when we may have to deflect a comet threatening to hit Earth. And NASA’s Stardust spacecraft collected material from the tail of a comet as it flew by in 2004, landing in Utah in 2006 with comet dust for analysis. Impressive, but not as impressive as the rendezvous of ESA’s spacecraft Rosetta with fast-moving 67P.