The number of scientific payloads on Aditya L – 1 mission for systematic study of Sun is

Question

UnlockIAS · Accepted Answer

Correct — A, 7. Aditya-L1, India's first dedicated solar observatory, carries seven scientific payloads, and they divide four to three. The four remote-sensing instruments look at the Sun: the Visible Emission Line Coronagraph (VELC), the primary payload, built by the Indian Institute of Astrophysics, Bengaluru, which images and takes spectra of the corona; the Solar Ultraviolet Imaging Telescope (SUIT) from the Inter-University Centre for Astronomy and Astrophysics, Pune, which images the photosphere and chromosphere in the 200 to 400 nanometre band; and two X-ray spectrometers from the U. R. Rao Satellite Centre, the Solar Low Energy X-ray Spectrometer (SoLEXS) for soft X-rays and the High Energy L1 Orbiting X-ray Spectrometer (HEL1OS) for hard X-rays, both observing the Sun as a star. The three in-situ instruments sample the space around the spacecraft: the Aditya Solar wind Particle Experiment (ASPEX) from the Physical Research Laboratory, Ahmedabad, for protons and heavier ions; the Plasma Analyser Package for Aditya (PAPA) from the Space Physics Laboratory at VSSC for electrons and heavier ions; and a pair of Advanced Tri-axial High Resolution Digital Magnetometers on a deployable boom, which measure the interplanetary magnetic field. The 1,500 kg spacecraft was launched on PSLV-C57 on 2 September 2023 from the Satish Dhawan Space Centre and was inserted into a halo orbit around the Sun–Earth Lagrange point L1, about 1.5 million km from Earth, on 6 January 2024 — 126 days after launch.

Why the other options are wrong — (b) Too few, and a plausible guess for anyone who remembers only the headline instruments — the coronagraph, the ultraviolet telescope and the two X-ray spectrometers — and forgets that the in-situ package is counted as three separate payloads, including the magnetometers.  (c) One short, which is exactly what happens if the tri-axial digital magnetometers are treated as instrument hardware rather than as a payload in their own right. ISRO's own payload table lists them as the seventh payload, developed by the Laboratory for Electro Optics Systems, Bengaluru.  (d) Too many, and the option is there for the candidate who counts sub-sensors instead of payloads: ASPEX and PAPA each contain two separate spectrometer or probe units, so an instrument-by-instrument count inflates the total. The figure ISRO publishes, and the one the question wants, is seven payloads.

Concept: A Lagrange point is a position in the Sun–Earth system where the gravitational pull of the two bodies and the orbital motion of a spacecraft balance, so that the spacecraft keeps station with the Earth as both go round the Sun. L1 lies between the Earth and the Sun at about 1.5 million km — roughly one hundredth of the Earth–Sun distance — and it is the natural post for a solar observatory, because a satellite there has an uninterrupted view of the Sun with no eclipses or occultations by the Earth. Aditya-L1's science divides along the same line as its instruments. The remote-sensing payloads attack the classic unsolved problems of solar physics: why the corona is millions of degrees hotter than the visible surface below it, and how flares and coronal mass ejections begin. The in-situ payloads measure what actually arrives at L1 — the solar wind's particles and the interplanetary magnetic field — which is the raw material of space-weather forecasting, since a disturbance detected at L1 reaches the Earth some tens of minutes later.

State PCS 2025 Q111 — Science & Technology PYQ with Answer

State PCS 2025 Q111 — Science & Technology PYQ with Answer