Landing on a Comet: History is Being Made Today

For those of us who are fascinated with space missions, today is a great day.  For the first time in human history we will land a probe on a comet that is moving through space toward the inner part of the solar system.

Rosetta is a robotic space probe built and launched by the European Space Agency to perform a detailed study of comet 67P/Churyumov–Gerasimenko with both an orbiter and lander module.  The purpose of the mission is to solve the mysteries of comets, which are made from primordial material that predates the birth of the solar system.  Scientists hope to learn more about how the solar system formed and how comets carried water and complex organic molecules to the Earth that may have led to the evolution of life on Earth.

Mission Facts

• The mission is controlled from the European Space Operations Centre (ESOC), in Darmstadt, Germany.
• Rosetta was launched on 2 March 2004 on an Ariane 5 rocket from its Kourou spaceport in French Guiana.
• The main spacecraft consists of two components: the Rosetta space probe orbiter, which features 12 instruments, and the Philae robotic lander, with an additional nine instruments. 
• The Rosetta mission will orbit the comet 67P/C-G for 17 months and is designed to complete the most detailed study of a comet ever attempted. 
• It is hoped that these spacecraft will result in better understanding of comets and the early Solar System.
• During its long trip to the comet he spacecraft performed two asteroid flyby missions. 
• In 2000,  The craft completed its fly-by of asteroid 2867 Šteins in September 2008 and of Lutetia in July 2010.  
• Rosetta performed a Mars swing-by (flyby), and returned images.
• On 20 January 2014, Rosetta was taken out of a 31-month hibernation mode and continued towards the comet.   
• At the start of the mission, ESA officials had assumed the comet would be potato shaped and rated their chances of a successful landing at 75%. After seeing the shape and terrain of their target close up, those odds fell to around 50%, but climbed again as technical staff learned more about the landing site.
• To reach the comet, Rosetta has travelled more than four billion miles.
• The probe reached the comet on August 6, 2014. becoming the first spacecraft to orbit a comet.  Previous missions had conducted successful flybys of seven other comets.
• The cost of the mission is more than $1.5 billion.
• The probe has travelled more than four billion miles to reach the comet.
• Rosetta is travelling at speeds up to 83,000 miles per hour (135,000 km/hr).
• At the start of the mission, scientists estimated that the chance for a successful landing was around 75 percent.  Once the probe neared the comet and they saw the complex shape of the comet with a rougher than expected terrain, the odds fell to around 50 percent.  
• On November 12, 2014 the Philae robot was released from the Rosetta orbiter.  It took seven hours for the robot to descend by just gravity to the surface of the comet.  The landing did not go perfect, but the robot did successfully land.

From its orbit around the comet, the Rosetta probe has taken incredible high-resolution images of the comet.

Below is a selfie photo showing the solar panel of Rosetta with the comet in the background.  

The comet is around 2.5 miles long.

As the comet moves toward the sun, it is heating up -- which releases gas and dust.  This activity is expected to intensify as it gets closer to the sun.  By August of 2015, the comet will reach its closest point to the sun (1.3 Earth distances).  The lander will probably not survive that long, but the orbiter will stay with the comet.

The surface of the comet is not smooth.  Some of the ridges are 300 or 400 feet tall.

In the months to come, the mission will gather information on the comet's density, temperature and chemical makeup. It will also capture dust and gas released in ever more violent jets from the comet’s nucleus as it nears the sun.

Congratulations to the more than 2,000 scientists and engineers from the ESA as well as other space agencies for this great accomplishment!

CITES:
http://www.theguardian.com/science/2014/nov/12/rosetta-mission-philae-historic-landing-comet
http://en.wikipedia.org/wiki/Rosetta_%28spacecraft%29
http://www.space.com/24266-rosetta-comet-mission-photos-esa.html
http://www.esa.int