P. Venugopal

A comprehensive campaign planned

Nine rockets to blaze away from Thumba

THIRUVANANTHAPURAM: The Vikram Sarabhai Space Centre (VSSC) has said the analysis of atmospheric-ionospheric parameters being conducted in India during the annular solar eclipse occurring on January 15 will be “one of the most comprehensive [scientific] campaigns ever attempted during a solar eclipse anywhere in the world.”

In a press release here on Tuesday, the VSSC said this would be the longest annular solar eclipse of this millennium.

An annular eclipse occurs when the moon covers the centre of the sun, but not its edges. This leaves just a ring of the sun visible from the earth along the path of the moon’s shadow.

The VSSC will launch four sounding rockets from Thumba, near here, on Thursday to gather data from altitudes touching up to 116 km above the earth. These will be followed by five more sounding rockets on Friday. One larger rocket each will be launched from the Sathish Dhawan Space Centre at Sriharikota on Thursday and Friday to gather data from altitudes touching up to 548 km above the earth.

Close shot

At 1.14 pm on January 15, the eclipse will pass close to Thumba with 91 per cent obscuration of the sun. The edges of the eclipse will touch Sriharikota with 85 per cent obscuration of the sun, the VSSC said.

Although the central line of the path of the eclipse will miss the mainland of the peninsula, the path of the eclipse being 323 km wide, it will still be a unique opportunity to investigate the effects of the fast varying solar flux on the photochemistry and electrodynamics of different atmospheric regions, especially the equatorial mesopause and ionosphere-thermosphere regions, the VSSC said.

“The uniqueness of this eclipse is that it occurs during noontime, when the incoming solar radiation is at its maximum… Further, the obscuration of the sun during this eclipse is exceptionally long, about 11 minutes and eight seconds. The maximum obscuration occurs during noon hours (13:15 IST). As a consequence, it provides an opportunity to study, perhaps for the first time, the solar eclipse induced effects in the noontime equatorial region,” the VSSC said.

The ionosphere above 120 km becomes turbulent on certain days in the post-sunset period with structures or eddies appearing in ionization.

It will be an interesting problem to look into the possible generation of these turbulent structures during the peak eclipse period when the geophysical conditions are likely to resemble those of the post-sunset period, the VSSC said.

“Such a study [being undertaken during this eclipse] would certainly give more insights into the generation mechanism of these structures that pose a major threat to modern day GPS-based navigation systems,” the VSSC noted.

The VSSC expects that the interpretation of space data, gathered with the assistance of the sounding rockets, along with modern ground-based eclipse observations, will give new insights into the earlier eclipse observations also.