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STS-120 day 2 highlights

Flight Day 2 of Discovery's mission focused on heat shield inspections. This movie shows the day's highlights.


STS-120 day 1 highlights

The highlights from shuttle Discovery's launch day are packaged into this movie.


STS-118: Highlights

The STS-118 crew, including Barbara Morgan, narrates its mission highlights film and answers questions in this post-flight presentation.

 Full presentation
 Mission film

STS-120: Rollout to pad

Space shuttle Discovery rolls out of the Vehicle Assembly Building and travels to launch pad 39A for its STS-120 mission.


Dawn leaves Earth

NASA's Dawn space probe launches aboard a Delta 2-Heavy rocket from Cape Canaveral to explore two worlds in the asteroid belt.

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Dawn: Launch preview

These briefings preview the launch and science objectives of NASA's Dawn asteroid orbiter.

 Launch | Science

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Keeping our skies safe



Posted: 09 January, 2009

The Catalina Sky Survey (CSS), which has discovered around 70 percent of all Near Earth Objects (NEOs) in the past three years, has been awarded a substantial NASA grant to continue its search through to 2012.

In 2008 alone, the University of Arizona’s CSS tallied 565 discoveries of NEOs, and thanks to a NASA grant worth $3.16 million, as well as private donations, the CSS is set to become even more productive this year and through to 2012, at least. A newly refurbished automated telescope, which will become operational this summer, "represents a huge increase in potential survey productivity," says CSS co-investigator Ed Beshore. Combined with a new high-speed communications link, scientists will be able to quickly access observational data and follow up NEO discoveries, increasing the team's surveying time on other telescopes by 20 to 25 percent.

The Catalina Sky Survey is well on the way to tracking all Earth-approaching objects greater than one kilometre in diameter. Image: CSS/R.Kowalski.

CSS is the only NEO survey that has telescopes in both hemispheres, and began receiving NASA funding in 1998 as part of the 10-year, congressionally mandated national Spaceguard program to detect, track, catalogue and characterise potentially hazardous asteroids and comets that could pose a threat to the Earth. The primary goal has been to locate at least 90 percent of Earth-approaching objects at or larger than one kilometre in diameter by the end of the decade. "We're about 85 percent there," says Larson.

In 2005 a further goal was specified to identify and assess
potentially hazardous near-Earth asteroids and comets 140 metres in diameter. That is, objects that would have the potential to wipe out entire cities. Fortunately, an impact of this scale would likely occur only once every several thousand years. While a frightening prospect, it must be remembered that cities only occupy a very small fraction of the Earth’s surface compared with uninhabited deserts, forests and so on.

"A key point of our survey is that we do nearly real-time analysis of the objects which we think may be NEOs," says Larson. "We can get more observations per night, extend the object's observed orbital arc to better establish whether it is a near-Earth object, then alert others to get more follow-up observations."

The CSS team proved the power of their technique early last October, when CSS observer Richard Kowalski discovered Asteroid 2008 TC3 using the Mount Lemmon telescope in Tucson. Two metre wide 2008 TC3 careered into the Earth’s atmosphere and disintegrated over Sudan just 19 hours after its discovery. Such small impact events are common, but this is the first time that astronomers discovered an asteroid before it reached Earth and successfully predicted when and where the impact would be.

The impact of 2008 TC3 was captured by weather satellite Meteosat 8. The scale at right gives the temperature in kelvin. Image: EUMETSAT.

"There's a bit of a misperception that what we do is find objects that are incoming, like the Sudan object," says Larson. "That's not the case. We're hoping to find objects that many orbits down the road might be hazardous, so that we have enough time to do something about them. We can calculate orbits quite accurately. We hope that we would have a few decades to study and characterise these things, and come up with the best plans to nudge them into another orbit so that it misses the Earth."

According to officials at NASA’s Near Earth Object Program, as of the new year, 5,955 NEOS have already been identified, including 763 asteroids at least 1 kilometre in diameter, and 1,008 NEOs larger than 140 metres and on orbits that take them within 4.5 million miles of the Earth. They are therefore classified as potentially hazardous objects because they may be perturbed into impacting trajectories in the future.

With CSS’s latest monetary top up, astronomers will soon have the power to complete their survey of Earth-threatening NEOs.