Constellation of satellites needed for disaster management

Constellation of satellites needed for disaster management

Mumbai: The Indian Space Research Organisation (Isro) has stressed on the need to have a constellation of satellites with multisectral sensors to predict, mitigate and manage disasters.

“Exactly how many satellites an effective constellation would need is still open for debate. No single satellite can hope to meet all these needs. Rather, what disaster managers need is a constellation of satellites carrying a range of sensors," Director, Space Application Centre Isro, Ranganath Navalgund said from Ahmedabad Thursday.

The constellation plan is a part of the ‘Umbrella Plan’ of the organisation, he said.

Disasters come in all shapes and sizes, needing varying data during the disaster cycle of mitigation, preparedness, response and recovery, Navalgund said.

Many studies suggest at least eight satellites, with dual capability sensors can collect both high and low spatial resolution data, and an equal split between optical (including thermal) and microwave instruments.

“The satellites should also be agile, they should allow rapid changes in camera orientation so that a disaster area can be kept in view longer," he said.

However, India currently makes use of data from different satellites which are already operating for disaster management.

Even yesterday’s cyclone ‘Phyan’ in Arabian sea was tracked by INSAT-3A Kalpana and recently launched Oceansat-2 with KU band and scatterometer, he said.

Crucially, different situations need data collected in different wavebands — like optical and near infrared data can map land use or assess agricultural droughts.

“But to track a cyclone’s eye, or monitor flooded areas beneath cloud, microwave sensors are needed," Navalgund said.

In flood monitoring, this can pose a real problem.

Low spatial resolution data can map out large inundated areas, but relief efforts really need more detailed, yet still timely, data on infrastructure, like submerged bridges, drains and roads,“ SAC director said.

A constellation of polar-orbiting satellites, equally spaced around a sun-synchronous orbit to provide continuous coverage over any given place, could solve this, he said.

Such a constellation, designed primarily for disaster management, could offer more frequent data in the right part of the spectrum and India is planning on these lines.

Geostationary satellites, predominantly designed for weather forecasting, are good at spotting a cyclone’s forming, tracking its movements, and predicting land fall points. But they don’t usually carry microwave sensors, which are needed to estimate a cyclone’