Spaceflight Now Home



Spaceflight Now +



Premium video content for our Spaceflight Now Plus subscribers.

Soyuz docking
The Russian Soyuz TMA-8 spacecraft carrying the Expedition 13 resident crew successfully docks to the Zarya module of the International Space Station under automated control.

 Play video

Next station crew
Full coverage of the Expedition 13 crew's launch aboard a Russian Soyuz spacecraft to begin a six-month mission aboard the International Space Station.

 Play video

Solar eclipse from ISS
External cameras on the International Space Station captured this incredible footage of the March 29 solar eclipse. The station flew through the eclipse over the Middle East as the moon passed in front of the sun and cast its shadow on the Earth.

 Play video

Total solar eclipse
A total solar eclipse occurred March 29. This video from Side, Turkey shows the period of totality when the moon slid between the Earth and Sun. The eclipse revealed the Sun's glowing outer halo of million-degree gas, called the solar corona.

 Play video

Dawn mission reborn
In early March, NASA cancelled its Dawn mission built to orbit two of the solar system's largest asteroids using ion engine propulsion. Technical problems and cost overruns were blamed. But in this news conference from March 27, agency officials announce NASA's decision to reverse the cancellation and restart the mission.

 QuickTime | For iPod

CEV planning
Lockheed Martin holds this news conference in Houston on March 24 to announced that it is partnering with the State of Texas to locate the Crew Exploration Vehicle (CEV) program office in Houston, as well as systems engineering, software development and qualification testing, if the corporation wins the NASA contract to build the next generation spacecraft for NASA.

 QuickTime | For iPod

Expedition 12 recap
As the Expedition 12 mission aboard the International Space Station winds down, officials managing the flight from Mission Control in Houston hold this retrospective briefing to talk about the highs and lows, the science, the spacewalks and everything in between.

 Dial-up video:
   Part 1 | Part 2

 Broadband video:
   Part 1 | Part 2

Become a subscriber
More video



Massive amounts of water released by comet hit
ROYAL ASTRONOMICAL SOCIETY NEWS RELEASE
Posted: April 4, 2006

Over the weekend of 9-10 July 2005 a team of UK and US scientists, led by Dr. Dick Willingale of the University of Leicester, used NASA's Swift satellite to observe the collision of NASA's Deep Impact spacecraft with comet Tempel 1.

Reporting today (Tuesday) at the UK 2006 National Astronomy Meeting in Leicester, Dr. Willingale revealed that the Swift observations show that the comet grew brighter and brighter in X-ray light after the impact, with the X-ray outburst lasting a total of 12 days.

"The Swift observations reveal that far more water was liberated an d over a longer period than previously claimed," said Dick Willingale.

Swift spends most of its time studying objects in the distant Universe, but its agility allows it to observe many objects per orbit. Dr. Willingale used Swift to monitor the X-ray emission from comet Tempel 1 before and after the collision with the Deep Impact probe.

The X-rays provide a direct measurement of how much material was kicked up after the impact. This is because the X-rays were created by the newly liberated water as it was lifted into the comet's thin atmosphere and illuminated by the high-energy solar wind from the Sun.

"The more material liberated, the more X-rays are produced," explained Dr. Paul O'Brien, also from the University of Leicester.

The X-ray power output depends on both the water production rate from the comet and the flux of subatomic particles streaming out of the Sun as the solar wind. Using data from the ACE satellite, which constantly monitors the solar wind, the Swift team managed to calculate the solar wind flux at the comet during the X-ray outburst. This enabled them to disentangle the two components responsible for the X-ray emission.

Tempel 1 is usually a rather dim, weak comet with a water production rate of 16,000 tonnes per day. However, after the Deep Impact probe hit the comet this rate increased to 40,000 tonnes per day over the period 5-10 days after impact. Over the duration of the outburst, the total mass of water released by the impact was 250,000 tonnes.

One objective of the Deep Impact mission was to determine what causes cometary outbursts. A simple theory suggests that such outbursts are caused by the impact of meteorites on the comet nucleus. If this is the case, Deep Impact should have initiated an outburst.

Although the impact was observed across the electromagnetic spectrum, most of what was seen was directly attributable to the impact explosion. After 5 days, optical observations showed that the comet was indistinguishable from its state prior to the collision. This was in stark contrast to the X-ray observations.

The analysis of the X-ray behaviour by the Swift team indicates that the collision produced an extended X-ray outburst largely because the amount of water produced by the comet had increased.

"A collision such as Deep Impact can cause an outburst, but apparently something rather different from the norm can also happen," said Dr. Willingale. "Most of the water seen in X-rays came out slowly, possibly in the form of ice-covered dust grains."

The UK role in Swift has been to provide core elements of the narrow field instruments (the X-ray telescope and the UV/Optical telescope), utilising mature technology already developed for the ESA XMM-Newton mission, and the JeT-X instrument.

Lead role in the X-ray telescope design, focal plane camera assembly and X-ray design (using past experience from JET-X and XMM-Newton). The UK Swift Science Data Centre at Leicester will provide an archive of all Swift data, with open access for the wider UK astronomical community.

The major part of the UV/Optical telescope was constructed at MSSL using designs and expertise from the XMM-Newton Optical Monitor.

The Deep Impact mission was managed by NASA's Jet Propulsion Laboratory, Pasadena, California. Swift is a medium-class NASA explorer mission in partnership with the Particle Physics and Astronomy Research Council in the United Kingdom and the Italian Space Agency. The Swift mission is managed by NASA Goddard. Penn State controls science and flight operations from the Mission Operations Center in University Park, Pennsylvania.

The spacecraft was built in collaboration with national laboratories, universities and international partners, including Penn State University; Los Alamos National Laboratory, New Mexico; Sonoma State University, Rohnert Park, Calif.; Mullard Space Science Laboratory, Dorking, Surrey, UK; the University of Leicester, UK; Brera Observatory in Milan; and the ASI Science Data Centre in Frascati, Italy.