A Match Made in Heaven
Kevin D. Conod is the planetarium manager & astronomer at the Newark Museum’s Dreyfuss Planetarium.
A NASA spacecraft and a comet will make a rendezvous on Valentine’s Day. The Stardust spacecraft will encounter Comet Tempel 1 on Monday, February 14, 2011.
This is a second time around for both. Stardust flew past Comet Wild 2 back in 2004. It was the first spacecraft to collect dust from a comet and return it to Earth. Results from Stardust revealed that the Solar System’s early history was more complex than originally thought.
This is one of the reasons why astronomers study comets. They have been hanging around the Solar System since its formation 4.5 billion years ago. They are like time capsules that can teach us about the history and formation of the planets.
Comets can be thought of very dirty snowballs. They are about 85% water ice, plus frozen gases such as carbon monoxide, carbon dioxide, methane and ammonia. They also contain rock and dust. When close to the Sun the ice sublimates (melts), releasing the dust that forms a comet’s distinctive tail. About 4,000 comets have been discovered, but that is only a tiny fraction of the comets thought to exist in our Solar System.
This will actually be the second to visitor to Comet Tempel. In 2005, the Deep Impact spacecraft not only flew past it but also dropped a probe onto its surface. The probe was designed to impact the surface so that Deep Impact could examine its composition. The probe’s impact left behind a crater that was as wide as a football field and 100 feet deep. Deep impact discovered that Tempel has a very dry powdery surface.
German astronomer Wilhelm Tempel discovered the comet that now bears his name in 1867. It orbits the Sun every 5.5 years. It is about 3 miles wide by 5 miles long.
Stardust’s flyby of Comet Tempel on Valentine’s Day will allow us to study the changes that have occurred on its surface over the last five years. Stardust will also be able to study Tempel’s dust and allow a direct comparison to Comet Wild 2 with the same instruments.
Stardust will come within 125 miles of the surface, allowing high-resolution imaging. With a bit of luck it will be able to measure the crater left behind by Deep impact and peer under the comet’s crust.
Stardust will be closest to Comet Tempel at 5:40 p.m. on Monday. The comet is too far from the Earth to be seen in small backyard telescopes, but you can view the latest images from the encounter online. See: stardustnext.jpl.nasa.gov.
Note the Deep Impact spacecraft also had a second encounter of its own: it flew past Comet Hartley 2 in November 2010. For images from that flyby visit: epoxi.umd.edu.
Visit newarkmuseum.org for more information.