The Sun does not just light the solar system. It wraps it. A constant wind of charged particles streams outward from the Sun in every direction, pushing against the thin gas and dust between the stars until the two reach a standoff, tens of billions of kilometres out. The region inside is the heliosphere, and it is why life on Earth is possible: the bubble deflects most of the high-energy cosmic rays that the galaxy would otherwise pour onto us. On Wednesday NASA launched a spacecraft from Kennedy Space Center in Florida to map it: the Interstellar Mapping and Acceleration Probe, or IMAP.
What IMAP will do
The probe carries instruments to detect particles and radiation and to measure magnetic fields. From its station it will watch the solar wind in real time, and it will detect the particles that bounce back from the edge of the bubble — energetic neutral atoms that carry information about the boundary where the solar wind meets interstellar space. From those, scientists can build the first detailed map of the heliosphere’s shape and of how the Sun’s activity — its 11-year cycle, its flares and eruptions — inflates and deforms it. The larger question, in NASA’s words, is how the Sun protects us and how our solar system connects to the rest of the galaxy.
Where it is going
IMAP is headed for L1, the Sun–Earth Lagrange point about 1.5 million kilometres from Earth in the direction of the Sun, where the two bodies’ gravity balances and a spacecraft can hover indefinitely with a permanent, unobstructed view of the Sun. Several solar observatories already sit there. IMAP joins them with a specific practical job.
The 30-minute warning
Solar storms — bursts of plasma and radiation from the Sun — take a day or more to reach Earth, but the dangerous fast particles arrive much sooner, and the precise strength of a storm is only known when it passes a spacecraft upstream. IMAP’s data will be streamed continuously through a system called IMAP Active Link in Real-Time, giving forecasters roughly 30 minutes of notice before a storm reaches Earth. That is enough time to put satellites into safe mode, reroute aircraft off polar routes and warn power-grid operators. For Bangladesh, with a satellite of its own in orbit, a growing dependence on GPS-timed mobile networks and a grid already fragile, space weather is not an abstraction; a half-hour warning is the difference between a managed event and a bad night.
Source: NDTV, via Prothom Alo.
