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Two intriguing investigations -- One flight-proven spacecraft

Frequently Asked Questions

FAQs About the Targets


Q: Which comet is the EPOXI Mission flying past?
A: The EPOXI Mission had its encounter with comet Hartley 2 on 4 November 2010 at approximately 15:00 UTC. You can read more about what we knew about the comet before the encounter and check back as we post images and results revealing what we know about the comet after the encounter.

Q: What stars will be the focus of the transit observations?
A: The EPOCh team observed several stars as well as the Moon, Earth and Mars as part of its science.

Q: Will these be stars around which planets have already been discovered transiting or will the spacecraft be looking for new ones?
A: The target stars are ones which are known to have at least one planet. The spacecraft observed a number of transits and by seeing if there are any transit timing variations, the EPOCh scientists might be able to deduce the presence of previously undiscovered planets.

Q: How are samples collected?
A: This is not a sample collecting mission. We will just be using the Deep Impact Flyby spacecraft to observe planets around other stars and to observe a comet up close as we fly past it.

Q: Will any comet samples ever be available for viewing, (like the moon rock at the Smithsonian National Air & Space Museum)?
A: You'll have to check with the folks who work on Stardust -- that was a mission that collected dust samples from the tail of a comet.

Q: Why does the comet appear to have a greenish blue coma in color images?
A: From NASA Science: The coma contains cyanogen (CN), a poisonous gas, and diatomic carbon (C2). Both of these substances glow green when illuminated by sunlight. This is called "resonant fluorescence." Read the full article.

Q: How close will comet Hartley 2 come to the Earth?
A: Comet Hartley 2 came closest to Earth on 20 Oct 2010 when it was about 0.12AUs (18,000,000km, 11,000,000mi) away. The comet reached perihelion on 28 Oct 2010 (1.06 AUs from the Sun and about 0.13 AUs away from the Earth). DIF flew past on 4 November 2010 at a distance of about 700km (430mi). The comet was about 1.06 AUs from the Sun and 0.15 AUs from Earth at the time of the flyby.

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