What is the primary objective of the Lunar Trailblazer mission?

Question

UnlockIAS · Accepted Answer

Correct — A, To detect and map water on the Moon’s surface. NASA states the objective in a single line: Lunar Trailblazer was to orbit the Moon to detect and map water on the surface, determining the form, the abundance and the distribution of water across the lunar surface. Each of those three words is a separate open question. Form — lunar water may sit as ice on the floors of permanently shadowed polar craters, or be chemically locked as hydroxyl (OH) and H2O inside rock and regolith, or condense briefly as frost that the moving shadow line drives back into the exosphere to settle somewhere colder. Abundance — nobody yet knows within an order of magnitude how much is there. Distribution — the mission was built to pinpoint 'micro-cold traps' smaller than a football field, shadow pockets far below the resolution of earlier orbiters. The payload settles the matter, because there are only two instruments and both serve that one aim. HVM3, the High-resolution Volatiles and Minerals Moon Mapper built at NASA's Jet Propulsion Laboratory, is an imaging spectrometer sensitive to the distinct spectral fingerprints of each form of water. The Lunar Thermal Mapper, built by the University of Oxford in the United Kingdom, measures the surface's temperature properties — necessary both because the surface's own thermal emission sits on top of the near-infrared water bands and because temperature decides where frost can survive at all. There is no altimeter, no stereo camera, no lander, no rover. The mission was selected in 2019 under NASA's SIMPLEx (Small Innovative Missions for Planetary Exploration) competition, was managed by JPL with the science investigation led by Caltech, and the spacecraft was built by Lockheed Martin. One honest note for anyone reading this after the exam: the mission itself failed. It launched on 26 February 2025, controllers lost contact the very next day, and NASA formally ended the mission on 31 July 2025 — roughly six weeks before this paper was set. The question asks what it was designed to do, and that answer does not change.

Why the other options are wrong — (b) Global 3D shape modelling of the Moon is the work of laser altimeters and stereo cameras — LOLA on NASA's Lunar Reconnaissance Orbiter, or the terrain camera and laser altimeter on Japan's SELENE/Kaguya, which produced the first full global lunar topographic model. Lunar Trailblazer carried neither instrument type. It was a box-shaped smallsat about 3.5 m across with its solar arrays open, flying to revisit selected water-bearing targets under changing illumination rather than to close a uniform global grid. A spectrometer plus a thermal radiometer cannot generate topography at all.  (c) Lunar Trailblazer was an orbiter and only an orbiter — no lander, no descent stage, no wheels, no surface mobility hardware of any kind. Rover technology on the Moon is demonstrated by surface missions: ISRO's Pragyan, which rolled off the Vikram lander near the south pole in August 2023, China's Yutu rovers, and NASA's water-prospecting VIPER. The pull of this option comes entirely from the mission's name, which sounds like a trail being physically blazed; NASA's sense of 'Trailblazer' is that it pioneered a low-cost class of planetary smallsat, not that it drove anywhere.  (d) This option holds only if at least two of (a), (b) and (c) describe the mission's primary objective. Only (a) does. Options (b) and (c) describe capabilities the spacecraft physically lacked — no altimeter or stereo camera, and no rover or lander. BPSC attaches this fourth option to almost every item in this section of the paper, and it works as a confidence test: candidates who half-recognise a mission name reach for it as a hedge. The discipline is to disprove each statement against a concrete fact — here, the two-instrument payload — before treating the combined option as safe.

Concept: For two centuries the Moon was assumed to be bone-dry. The Apollo samples returned between 1969 and 1972 showed no water, and with no atmosphere and no magnetic shield anything volatile on the sunlit surface should be baked off or stripped away by the solar wind. That consensus broke in 2008–09, and India broke it: the Moon Mineralogy Mapper (M3), a NASA imaging spectrometer flown on ISRO's Chandrayaan-1, found a roughly 3-micrometre absorption feature across wide areas of the surface — the fingerprint of hydroxyl and water bound in the top few millimetres of regolith — while Chandrayaan-1's Moon Impact Probe sensed water in the tenuous lunar exosphere. Since then lunar water has been understood in three physically distinct states, and telling them apart is what every modern lunar mission chases. First, ice, thermally stable only inside permanently shadowed regions near the poles, where crater floors have not seen direct sunlight for extremely long periods and temperatures stay low enough that a water molecule which arrives essentially never leaves — a cold trap. Second, hydroxyl and water chemically bound into minerals and impact glass, produced in part by solar-wind protons reacting with oxygen already in the regolith. Third, a transient frost that forms in cold shadow, sublimates as the shadow sweeps through the lunar day, hops through the exosphere and re-condenses somewhere colder. Only an imaging spectrometer can separate these, because each leaves a different absorption band; and only a simultaneous temperature measurement makes that reading trustworthy, since the surface's own thermal emission overlaps the same wavelengths. The stakes are not purely scientific. Polar water means drinking water, breathable oxygen and hydrogen–oxygen propellant manufactured in place rather than lifted out of Earth's gravity well, which is why Artemis, VIPER and Chandrayaan all point at the south pole.

State PCS 2025 Q16 — Science & Technology PYQ with Answer

State PCS 2025 Q16 — Science & Technology PYQ with Answer