AltiKa - Call for proposals until 15 February
18 January 2010
On 15 December 2009, France and India issued a call for proposals from the international scientific community to exploit data from AltiKa, a high-resolution altimeter dedicated to measuring oceans, continental waters and ice.
Compact and accurate
How altimetry works: the satellite measures the return-trip time of a radar signal bounced off Earth’s surface. Credits: CNES.
“AltiKa, to be flown on the Indian SARAL1 satellite, is set to take over from Envisat’s ocean-monitoring sensor,” explains Eric Thouvenot, SARAL-AltiKa Programme Manager at CNES. “It’s quite an innovative altimeter, the first to operate at such a high frequency, which makes it more compact and delivers better performance than the previous generation.”
Satellite-borne altimeters determine sea level by bouncing a radar signal off the surface and measuring the return-trip time.
But Earth’s atmosphere slows down the signal, so altimetry measurements are skewed.
AltiKa gets round this problem by operating at a high frequency in Ka band, which also means it doesn’t have to carry an instrument to correct for atmospheric effects as current-generation altimeters do
Another advantage afforded by operating at higher frequencies is greater accuracy.
“AltiKa will measure ocean topography with an accuracy of
“AltiKa will provide accurate measurements of ocean topography, particularly near coastlines. It’s important to be able to acquire valid data near land masses because more and more applications are now focusing on coastal areas,” he underlines.
From oceans to lakes and glaciers
How the DORIS system works: data are sent to the SSALTO multi-mission processing centre. Credits: CNES.
Besides oceanographers and climatologists, glaciologists and hydrologists are also eagerly awaiting more accurate data than ever before on glaciers, inland seas, lakes and rivers>.
With the aid of the
If there is one weak point, it is that “high-frequency radar waves are extremely sensitive to rain, even drizzle,” Eric Thouvenot acknowledges. “But, statistically, we expect to lose only 10% of data. And some scientists believe they can interpret attenuation and distortion of radar waves by rain to derive new information,” he says with amusement.
What is certain is that AltiKa data are going to interest many research teams.
CNES and the Indian Space Research Organization (ISRO) are soliciting proposals until 15 February.
If everything goes according to plan, the SARAL satellite, carrying AltiKa and an Argos-3 instrument2, will be launched late 2010-early 2011.
“We’re confident this project is going to succeed,” concludes Eric Thouvenot.
1 Satellite with
2 Environmental data collection and location system