Challenger 51-L

January 28, 1986

Christa McAuliffe

“…The Challenger Crew was pulling us into the future and we will continue to

follow them.” -- President Ronald Reagan

Comet HalleyNext approach: July 2061

Comet EnckeNext approach: October 2013

Why Study Comets?Why Study Comets?

Scientific ResearchScientific Research

Prevent a comet Prevent a comet from colliding with from colliding with EarthEarth

Potential resources Potential resources for future missionsfor future missions

Comet Facts Comets are made of: Ice Rock Dust Gases

How comets get their names Named for the person

who observed the comet and analyzed its orbital path

Names assigned by the International Astronomical Union

Short period/long period < 200 years = short

period > 200 years = long

period

Anatomy of a Comet

Nucleus

Coma White Dust Tail

Blue Gas Tail

Comet Encke

Discovered by Johann Franz Encke in 1819

Orbital Period: 3.3 years

Magnitude: 7

Eccentricity: 0.8471

Mass Density: 0.6 g/cm3

0.4 to 0.9 g/cm3

none detected1.0 to 8.0 g/cm3 None- 8 to + 6

none detected0.7 to 5.4 g/cm3 0.0 to 0.3+ 4.5 to + 13.6

CO, NH3, CH4, H,

CN, CO2, O2,

N2

Less than 0.98 = short period comet

Greater than 0.98 = long period comet

- 1.7 to + 11

He2, H2, C, N2, O2 None- 15 to + 6

CO2, H2, He2, N20.7 to 5.4 g/cm3 0.0 to 0.2- 4 to + 0.7

Meteor

Asteroid

Comet

Supernova

Planet

GASESMASS DENSITY(mass per unit volume)

ECCENTRICITY(range of 0 to 1; 0 = circle)

MAGNITUDE(scale of brightness)

OBJECT

varies

NASA Comet Missions

Mission Name Launch DateGalileo October 18, 1989

Deep Space 1 October 24, 1998

Stardust February 7, 1999

Contour July 3, 2002

Rosetta March 2, 2004

Deep Impact January 12, 2005

Deep Impact/Epoxi October 11, 2010

Good Luck

On

Your Mission!

Good Luck

On

Your Mission!