JPL: Epoxi Spacecraft Burns for Home, Then Comet

[bystander]

Spacecraft Burns for Home, Then Comet
NASA JPL Epoxi - 2010-185 - 28 May 2010

[b]Artist's concept of EPOXI, which uses the Deep Impact spacecraft. [i](Credit: Ball Aerospace)[/i][/b]

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NASA's Deep Impact/Epoxi spacecraft has successfully performed a trajectory correction maneuver to refine its orbit prior to an upcoming Earth flyby June 27. The maneuver, along with the Earth flyby, will place the spacecraft on a trajectory to fly past comet Hartley 2 on Nov. 4.

The maneuver began at 2 p.m. EST (11 a.m. PST) today, when the spacecraft fired its engines for 11.3 seconds. While the burn changed the spacecraft's velocity by only 0.1 meters per second (less than a quarter mile per hour), that was all the mission's navigators requested to set the stage for an Earth gravity assist on June 27.

"While it was a small burn, it was a big step in getting us to Hartley 2," said Tim Larson, project manager of NASA's Epoxi mission. "Humanity's fifth close-up view of a comet is less than five months away."

Epoxi is an extended mission of the Deep Impact spacecraft. Its name is derived from its two tasked science investigations -- the Deep Impact Extended Investigation (DIXI) and the Extrasolar Planet Observation and Characterization (EPOCh).

For information about Epoxi, visit http://www.nasa.gov/epoxi.

[bystander]

Earth to Lend Helping Hand to Comet Craft
NASA JPL EPOXI - 2010-211 - 25 June 2010

NASA's Deep Impact/EPOXI spacecraft will fly past Earth this Sunday (June 27). Mission navigators have tailored this trajectory so the spacecraft can "hitch a ride" on Earth's gravity field, which will help propel the mission toward its appointment with comet Hartley 2 this fall. At time of closest approach to Earth, the spacecraft will be about 30,400 kilometers (18,900 miles) above the South Atlantic.

"Earth is a great place to pick up orbital velocity," said Tim Larson, the EPOXI project manager from NASA's Jet Propulsion Laboratory in Pasadena, Calif. "This flyby will give our spacecraft a 1.5-kilometer-per-second [3,470 mph] boost, setting us up to get up close and personal with comet Hartley 2."

[bystander]

'Hitchhiker' EPOXI: Next Stop, Comet Hartley 2
NASA JPL EPOXI - 2010-216 - 28 June 2010

NASA's Deep Impact/EPOXI spacecraft flew past Earth Sunday (June 27) at approximately 3:03 p.m. Pacific time (6:03 p.m. Eastern time), as planned. The spacecraft is now on its way to its appointment with comet Hartley 2 this fall. The members of the EPOXI team at NASA's Jet Propulsion Laboratory in Pasadena, Calif., are currently working with data returned from the flyby to refine the spacecraft trajectory estimates.

EPOXI is an extended mission of the Deep Impact spacecraft. Its name is derived from its two tasked science investigations -- the Extrasolar Planet Observation and Characterization (EPOCh) and the Deep Impact Extended Investigation (DIXI). On Nov. 4, 2010, the mission will fly by Hartley 2 using all three of the spacecraft's instruments (two telescopes with digital imagers and an infrared spectrometer).

[bystander]

Tally-Ho! Deep Impact Spacecraft Eyes Comet Target
NASA JPL EPOXI | 2010-291 | 08 Sept 2010

60 Days before its flyby, EPOXI takes a picture of its quarry - Comet Hartley 2. [i](Credit: NASA/JPL/UM)[/i]

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On Sunday, Sept. 5, NASA's Deep Impact spacecraft beamed down the first of more than 64,000 images it's expected to take of Comet Hartley 2. The spacecraft, now on an extended mission known as EPOXI, has an appointment with the comet on Nov. 4, 2010.

It will use all three of the spacecraft's instruments (two telescopes with digital color cameras and an infrared spectrometer) to scrutinize Hartley 2 for more than two months....
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The imaging campaign, along with data from all the instruments aboard Deep Impact, will afford the mission's science team the best extended view of a comet in history during its pass through the inner solar system. With the exception of one, six-day break to calibrate instruments and perform a trajectory correction maneuver, the spacecraft will continuously monitor Hartley 2's gas and dust output for the next 79 days.

This first image of comet Hartley 2 taken by Deep Impact was obtained by the spacecraft's Medium Resolution Imager on Sept. 5 when the spacecraft was 60 million kilometers (37.2 million miles) away from the comet.

[neufer]

Comet 103P passing within 0.12AU of Earth on October 20, 2010.

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<<Comet Hartley 2, officially designated 103P/Hartley is a small periodic comet with an orbital period of 6.46 years. It was discovered by Malcolm Hartley in 1986 at the Schmidt Telescope Unit in Siding Spring, Australia. Its diameter is estimated to be 1.2 to 1.6 km. There is a planned flyby of Hartley 2 by the Deep Impact spacecraft with a closest approach of 700 kilometers on November 4, 2010. This is part of the EPOXI mission.

The comet will pass within 0.12 AU of the Earth on October 20, 2010, which is only eight days before coming to perihelion (closest approach to the Sun) on October 28, 2010. During this passage, the comet may be visible to the naked eye at apparent magnitude 5, in the constellation Cygnus, if you know where to look and are viewing from a dark sky location. Binoculars should make it an easy target.

Observation by the Spitzer Space Telescope in August 2008 showed the comet nucleus to have a radius of 0.57 ± 0.08 km and a low albedo of 0.028. The mass of the comet is estimated to be about ~3 × 10¹¹ kg. Barring a catastrophic breakup or major splitting event, the comet should be able to survive up to another 100 apparitions (~700 years) at its current rate of mass loss. After the 2010 perihelion passage, not accounting for nongravitational forces, Hartley 2 is estimated to come back to perihelion around April 20, 2017.>>

[bystander]

EPOXI Mission Sets Up for Comet Flyby
NASA JPL EPOXI | 29 Sept 2010

[b]Artist's concept: NASA's Deep Impact/EPOXI spacecraft flew past Earth on June 27, 2010, to get a boost from Earth’s gravity. It is now on its way to comet Hartley 2, with a planned flyby this fall. [i](Credit: NASA/JPL-Caltech)[/i][/b]

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Earlier today, navigators and mission controllers for NASA's EPOXI mission watched their computer screens as 23.6 million kilometers (14.7 million miles) away, their spacecraft successfully performed its 20th trajectory correction maneuver. The maneuver refined the spacecraft's orbit, setting the stage for its flyby of comet Hartley 2 on Nov. 4. Time of closest approach to the comet was expected to be about 10: 02 a.m. EDT (7:02 a.m. PDT).

Today's trajectory correction maneuver began at 2 p.m. EDT (11 a.m. PDT) today, when the spacecraft fired its engines for 60 seconds, changing the spacecraft's velocity by 1.53 meters per second (3.4 mph).

"We are about 23 million miles and 36 days away from our comet," said EPOXI project manager Tim Larson of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "I can't wait to see what Hartley 2 looks like."

On Nov. 4, the spacecraft will fly past the comet at a distance of about 700 kilometers (435 miles). It will be only the fifth time in history that a spacecraft has been close enough to image a comet's nucleus, and the first time in history that two comets have been imaged with the same instruments and same spatial resolution.

"We are imaging the comet every day, and Hartley 2 is proving to be a worthy target for exploration," said Mike A'Hearn, EPOXI principal investigator from the University of Maryland, College Park.

[bystander]

Comet Hartley 2 approaches Earth
PhysOrg | Space Exploration | 30 Sept 2010

[i]Credit: NASA/MSFC/Bill Cooke, NASA's Meteoroid Environment Office[/i]

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A pale green interloper among the stars of Cassiopeia, Comet Hartley 2 shines in this four-minute exposure taken on the night of Sept. 28, 2010, by NASA astronomer Bill Cooke.

Still too faint to be seen with the unaided eye, the comet was 18 million miles away from Earth at the time. Cooke took this image using a telescope located near Mayhill, N.M., which he controlled via the Internet from his home computer in Huntsville, Ala.

Comet-watching from the comfort of your living room? Modern astronomy is truly amazing...

Comet 103P/Hartley 2, a small periodic comet, was discovered in 1986 by Malcolm Hartley, an Australian astronomer. It orbits the sun about every 6.5 years, and on Oct. 20, the comet will make its closest approach to Earth since its discovery.

In this case, "close" means 11 million miles, or 17.7 million kilometers. A moonless sky will make for promising viewing conditions in the northeastern skies, especially just before dawn.

Provided by JPL/NASA