ISRO, NASA experiment to look for ice on moon ended in failure

New Delhi, Sep 13 (PTI) A National Aeronautics and
Space Administration (NASA) scientist has said that his joint
experiment with Indian Space Research Organisation (ISRO) to
look for ice in a permanently shadowed crater near the moon's
North Pole using Chandrayaan-I had failed.

Known as bi-static experiment, it involved coordinated
use of Chandrayaan-I and US space agency NASA's Lunar
Reconnaissance Orbiter (LRO) spacecraft.
Ahead of the experiment, LRO executed a minor
manoeuvre to adjust its orbit to Chandrayaan-I and both
spacecraft made observations of the Erlanger Crater from
different angles at the same time.
However, when NASA scientists analysed the data, they
found that Chandrayaan-I was not pointed to the moon when the
observations were being made.
"Everything worked out as best as could be hoped,
except for one thing. It turned out Chandrayaan-I was not
pointed at the moon when we were taking the data, but we
didn't know that at the time," said Paul Spudis, principal
investigator for Chandrayaan-I radar instrument, Mini-SAR told
science web journal 'Universe Today'.
The experiment was conducted on August 20 and
scientists were planning to make another set of observations
around last month end but Chandrayaan-I lost radio contact
with the ground station on August 29 forcing ISRO to bring the
mission to an abrupt end.

The experiment was attempted when both spacecraft were
only 20 kilometres apart over Erlanger Crater near the moon's
north pole.

Both the spacecraft were equipped with a NASA miniature
radio frequency instrument that functions as synthetic
aperture radar, known as MINI-SAR on Chandrayaan-1 and Mini-RF
on LRO.
Chandrayaan in transit mode transmitted the signals and
LRO received the reflected signals. The experiement used both
radars to point at the Erlanger Crater at the same time.

However, much to the scientists' dismay, they found that
Chandrayaan was pointed in the wrong direction and they had no
way of knowing it.

A star sensor onboard Chandrayaan-I, used to orient the
spacecraft in a particular direction had failed in April and
ISRO scientists had patched up two other instruments to
manoeuvre it to the desired location.

Scientists were planning to compare the signal picked up
by the LRO with the one picked up by Chandrayaan-I. The study
of the two signals would have provided them with unique
information about ice on the polar crater.

Space scientists from ISRO, Jet Propulsion Laboratory,
NASA and the John Hopkins University Applied Physics Lab
worked on the experiment.
Things are not as bad as they appear to be as the
Chandrayaan-I was able to collect some very high resolution
images of the lunar surface, particularly along the polar
region.
Scientists are analysing data covering 90 per cent of
the polar region which was collected between February and
April.
Chandrayaan-I was launched on October 22 last year.
The launch propelled India into a select group of moon-faring
nations.
Soon after the spacecraft was put into lunar orbit, a
moon impact probe sent to the lunar surface in a controlled
crash had placed Indian national tri-colour on the moon.
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