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By Emily Lakdawalla

SMART-1 Making an Impact

Oct. 3, 2006 | 11:38 PDT | 18:38 UTC

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by Doug Ellison

The SMART-1 lunar impact has been covered fairly well here before -- but Bernard Foing presented some brief highlights during a lunchtime update that I thought would be worth sharing. SMART-1 crashed into the Moon (intentionally) to end its mission just a few weeks ago and so the "mission" is over -- but Foing explained that scientists will now be working even harder on the data they have been collecting. SMART-1 was important in teaching ESA scientists and engineers about solar electric propulsion and gravity assist manoeuvres that will both directly feed forward to the mission design for ESA's BepiColumbo mission to Mercury early in the next decade.

Click to enlarge >

SMART-1 Impact Site
Credit: ESA - C. Carreau

SMART-1 also saw the first flight of a new generation of miniaturised instruments that are 5 to 10 times lighter than the current norm. One of these, a miniaturised camera called AMIE was used in a laser link experiment. A laser was fired from the island of Tenerife toward the spacecraft some 130,000 kilometres from Earth. Tests from lunar orbit were mentioned but not described in detail. AMIE was also used to take Earthset and Earthrise movies in August 2006.

Scientists have used the X-Ray spectrometer onboard to measure elemental composition of the surface, and, using samples returned by the Russian Luna 24 mission, they have been able to confirm the accuracy of the X-Ray spectrometer when observing the Luna 24 landing site and thus propagate the data from the X-Ray spectrometer across the entire surface.

Moving on to the impact itself -- you will all have seen the facts and figures so I will spare you the details, however the results they have so far are interesting. The observation of the impact is three fold. Firstly, the moment of impact itself, about 200 msec in duration -- looking for spectra within the flash, especially that of the hydrazine fuel that remained onboard. No details of results were given, but only one facility has so far reported results of seeing the flash – the 3.6 metre Canada France Hawaii Telescope ( CFHT ) using its infrared WIRCam using ten second exposures at a wavelength of 2122nm. The flash itself appears slightly distended in the direction of travel of the spacecraft at the time of impact. The second phase is observation of the ejecta, and CFHT caught this well for a couple of minutes, flying downrange in quite a large area. The final phase is follow-on observations from later lunar orbiting missions to observe the actual impact crater and resulting ejecta. The crater is expected to be around 5 to 10 metres in size and elongated because of the very low angle of impact.

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Lunar Impact as Seen from Earth
The 3.6-meter optical/infrared Canada-France-Hawaii Telescope (CFHT) in Hawaii captured this impressive sequence of SMART-1 impact images showing before, during, and after the impact. The impact flash -- which lasted only about 1 millisecond -- may have been caused by the thermal emission from the impact itself or by the release of spacecraft volatiles, such as the small amount of hydrazine fuel remaining on board. Credit: Canada-France-Hawaii Telescope Corporation

A delegate asked about the resolution of imagery before the impact, and remarkably, SMART-1 itself has probably provided the best resolution imagery of the impact site at around 50 metres per pixel. This means that there will not be particularly high resolution data from which to compare the post-impact high resolution data taken by spacecraft such as the Lunar Reconnaissance Orbiter in 2008/9. I asked Foing what plans there were to release SMART-1 data in the way that Mike Griffin had described the previous day -- a unified data format for all lunar data to be shared between agencies, countries, and scientists. He said that they are already beginning to put their data on the European version of the NASA Planetary Data Service called the PSA. I pushed him for a date, and he said that over the next 3 months the early data from the mission would go onto the PSA with the rest following. (insider UMSF joke…I tried Phil, I tried ☺. You will just have to keep on waiting you data-addict you!!)

Tuesday AM saw some Venus Express presentations, and tonight sees a lecture about Venus Express -- so later today I will try and put all of that together.