Deep Impact was the first mission to impact on a comet. NASA's Deep Impact Spacecraft was launched on 12th January 2005 aboard a Delta II from Cape Canaveral in Florida, USA. It took 6 months to reach its comet target - Comet Tempel 1. Deep Impact rendezvoused Comet Tempel 1 on July 4, 2005.

Artist Pat Rawlings gives us a look at the moment of impact and the forming of the crater.
Credit: NASA

The purpose of the Deep Impact mission was to study the structure of cometary nuclei, the comet's structure and makeup (both its surface and deep inside). The material seen may help to explain how our solar system was formed and help to understand the chemical composition of comets. The size of pieces knocked will be used to determine the comet’s strength.

Deep Impact Spacecraft is actually two spacecraft in one:

(1). A flyby ship (mothership) - Instruments on the Deep Impact mothership will observe and capture images on approach, when the impactor hits and during the flyby. The Deep Impact Spaceraft ( mothership) will pass by Comet Tempel 1 from a a safe distance of 500km (300miles).

After release the impact will target an illuminated area and not a dark area. The mothership will perform an evasive manoeuvre, plotting a trajectory to fly past the comet shortly after the impact. 

(2). Drop-probe impactor: The Impactor weighs 370kg (800 pound) and is 1m in diameter and 0.8m tall. It will use autonomous navigation computer, cameras and a propulsion system to guide itself toward a suitable impact point that is well lit.

To reduce the chance of the impactor’s materials being mistaken for cometary components, mission scientists built the impactor using substances unlikely to occur naturally in a comet ?it’s half copper by weight, for example.

Mission

Deep Impact probe cruised for 6 months before intercepting the comet beyond Earth’s orbit. On July 4, 2005, the probe released a self-guiding, camera-carrying kamikaze impactor to the surface of Comet Tempel 1 at 37,000kph creating a crater. Before, during and after the collision, Deep Impact Spacecraft (motheship) collected data and pictures. It was protected from flying debris by a dust shield.

Deep Impact History

NASA's Deep Impact has cost $267 million US dollars. The Deep Impact mission is managed for NASA by the Jet Propulsion Laboratory, Pasadena, California. The Principal Investigator is Dr. Michael A'Hearn, a prominent comet scientist from the University of Maryland. Ball Aerospace and Technologies Corporation, Boulder, Colorado, is responsible for all flight hardware. Deep Impact is first planetary science spacecraft for Ball Aerospace.

* In July 1999, NASA selected Deep Impact to be the eighth Discovery mission.

* Work on the Deep Impact mission began in January 2000.

* The NASA Deep Impact Spacecraft was launched on 12th January 2005 from Cape Canaveral in Florida for a 431 million km voyage that will take it on a collision course with the Tempel 1 comet.

* Two months before the encounter, Deep Impact Spacecraft will commence its scientific observations - how the comet nucleus rotates and examine the jets of gas and dust streaming away from Comet Tempel 1.

Aftermath - Viewing the Comet

Earth Ground based telescopes will monitor the comet before and after the collision. Space Observations will be made by the Hubble Space Telescope and Spitzer Space Telescope.

What will the impact look like? 

How Tempel 1 will react to the impact is unknown, but scientists do not believe the comet will break up. The size of the crater might be as big as a house or up to a football stadium. The collision will have an undetectably small effect on the comet’s orbit.

The expanding dust cloud should increase the comet’s visual brightness and might be detectable by backyard telescopes. We'll have to wait. Stay Tuned!

If the mission is successful, the images/pictures taken will be the highest resolution taken of a nucleus of a comet.

Tempel 1 Comet Facts

Comet Tempel 1 was discovered on 3 April 1867 by Ernst Wilhelm Leberecht Tempel in Marseilles, France. Comet Tempel 1 currently circles the Sun every 5.5 years. It's orbit lies between Mars and Jupiter. At impact Deep Impact Spacecraft will be 130 million km from Planet Earth.

The comet is a short-period comet, which means it orbits the Sun in an elliptic (oval) orbit, between Mars and Jupiter, every 5.5 years. It's nucleus is thought to have a 6.5km diameter and to consist of water and carbon. From oberservations made to date, the exact size and shape of the nucleus of Tempel 1 is unclear.

Did you know?

- Deep Impact Spacecraft maybe the ultimate display on America's 4th July Celebrations, which is Independence Day.

- Comets are basically frozen ice balls which circle the Sun. They may have played a vital role in bringing water and carbon-based molecules to Earth - the essential ingredients for life to begin.

- A comet or asteroid is believed by a many scientists to have caused the impact that changed Earth's climate and wiped out dinosaurs, 65 million years ago.

- Comets offer clues to some of the most fundamental questions about conditions when the planets were forming, more than four billion years ago.

- It's been done in films, but this is the first real attempt to impact a comet.

- There was a movie called Deep Impact.

- NASA's Stardust Spacecraft flew past Comet Wild 2 in January 2004, catching dust particles for return to Earth in 2006. Current mission Rosetta mission is flying to comet Churyumov-Gerasimenko where a lander will land on it.

- The impact will be the astronomical equivalent of a mosquito into the path of a Boeing 777 aeroplane - altering the comet's velocity by just 0.0001 millimetres per second.

- Every time a comet goes around the Sun, the surface gets heated and as a result changes the near surface. The impact may show how different the surface is from what's inside.

Related Space Books

Comet by Carl Sagan, Ann Druyan (Contributor)
From Amazon.com, Amazon.co.uk

Impact!: The Threat of Comets and Asteroids
by Gerrit L. Verschuur
From Amazon.com, Amazon.co.uk, Amazon.ca

 Deep Impact Links:

• Deep Impact: Home Page: Nasa. Picture Source
  
  
• NASA Disovery Program:
  
  
• Deep Impact: Ball Aerospace