Exploring Space: Images from NASA

From a rooftop observatory  in the city of Danzig (now Gdansk), Johannes Hevelius used his astronomical instruments  to search the sky. With items like a 150-foot refractor (extending over several houses) and an azimuth quadrant (fixing the location of his observations), Hevelius discovered the comets of 1652  and 1661.   In 1668, he published Cometographia  which, among other things, illustrates various comet forms.

Also in 1668, Stanislaus Lubienietzki  published his lavishly  illustrated  Theatrum Cometicum (“The Theatre of Comets”). Among its many pictures is a woodcut showing the perceived destructive influence of a fourth-century comet. His entire book is available at the National Digital Library of Poland. (Although that site goes offline occasionally, we encourage you to view its amazing contents.)

• The Great Comet of 1680 (discovered by Gottfried Kirch) was featured in Germany with captions like:   “New Miracles - A Large Comet-Star.”
  
  
• In 1682, Halley’s Comet (although not-yet called by that name) appeared in the European sky. One artist made it seem like the comet was extremely close to Earth.

In fact, comets are in orbit far above Earth. But ... what if it were possible to send a probe directly into a comet’s orbit? What if that probe could take pictures of the comet’s nucleus? What if the probe actually impacted the comet’s surface?

Those questions, and answers, are no longer speculative. Less than a thousand years after Halley’s Comet seemed like a bad omen in Britain - 939 years to be exact - NASA launched an unmanned mission, called "Deep Impact," to a comet, called Tempel 1, for an “up close and personal” look.

What was the plan? Send a spacecraft (called the “FLYBY”) to launch  a smaller spacecraft (called the “IMPACTOR”)   directly into the path of Tempel 1 (a comet about the size of Manhattan Island), causing a collision between the two. Flyby (repositioned safely out-of-the-way) would standby to observe and record what happened, transmitting electronic images to Earth.

Although many things could have gone wrong, FLYBY (after traveling 268 million miles, or 431 million kilometers) delivered IMPACTOR (battery-operated, thruster-equipped and made mostly of copper) which smacked into  Tempel 1 at speeds of 23,000 miles per hour. NASA’s animated recreation depicts those events of 3 July 2005.

After successfully completing its “Deep Impact” mission,  beginning the science of cometary geology, FLYBY went into sleep mode. NASA officials will “awaken it,” as needed, for other possible investigations.

Meanwhile, two other NASA vehicles have been hard at work - on Mars.