The altitude profiles of argon‐40 (Ar) in the Martian exosphere are reported using Mars Exospheric Neutral Composition Analyser aboard Indian Mars Orbiter Mission (MOM) from four orbits during December 2014 (Ls = 250°–257°), when MOM's periapsis altitude was the lowest. The upper limit of Ar number density corresponding to this period is ∼5 × 105 cm−3 (∼250 km), and the typical scale height is ∼16 km, corresponding to an exospheric temperature of ∼275 K. However, on two orbits, the scale height over this altitude region is found to increase significantly making the effective temperature >400 K. Neutral Gas and Ion Mass Spectrometer observations on the Mars Atmosphere and Volatile Evolution mission also indicate that the change in slope in Ar density occurs near the upper exosphere (around 230–260 km). These observations indicate significant suprathermal CO2 and Ar populations in the Martian exosphere. Significant wave‐like perturbations are observed but only on certain days when suprathermal population is seen. Pickup ion‐induced heating is discussed as the other viable source.

The Mars Exospheric Neutral Composition Analyser (MENCA) aboard the Indian Mars Orbiter Mission (MOM) is a quadrupole mass spectrometer which provides in situ measurement of the composition of the low‐latitude Martian neutral exosphere. The altitude profiles of the three major constituents, i.e., amu 44 (CO2), amu 28 (N2 + CO), and amu 16 (O) in the Martian exosphere during evening (close to sunset terminator) hours are reported using MENCA observations from four orbits of MOM during late December 2014, when MOM's periapsis altitude was the lowest. The altitude range of the observation encompasses the diffusively separated region much above the well‐mixed atmosphere. The transition from CO2 to O‐dominated region is observed near 270 km. The mean exospheric temperature derived using these three mass numbers is 271 ± 5 K. These first observations corresponding to the Martian evening hours would help to provide constraints to the thermal escape models.

Aditya-L1, the first ever Indian scientific space mission dedicated to probe the Sun, our nearest star, is slated for launch by the Indian Space Research Organisation (ISRO) most likely in 2020, the year coinciding with the expected start of the rising phase of solar cycle 25. Of the seven science payloads on-board Aditya-L1, three are in situ instruments, namely the Aditya Solar wind Particle EXperiment, the Plasma Analyser Package for Aditya and a magnetometer package. These three payloads will sample heliospheric data from the L1 Lagrangian point of the Sun-Earth system, at a distance of ~1% of the distance to the Sun, along the Sun-Earth line. This is therefore a unique opportunity for the solar physics community to gain a better understanding of the inner heliosphere and predict space weather more accurately.

Vertical coupling within atmosphere takes place through atmospheric waves as has been demonstrated in a number of studies in the past. Gravity waves are produced in the lower atmosphere and thereafter propagate vertically and horizontally, modulating the dynamics of the intervening regions. Kelley (1997) presented evidence of gravity waves propagating to ionospheric altitudes during a thunderstorm event. Long and short period gravity waves and their propagation characteristics have been discussed comprehensively by Fritts and Alexander (2003). Yamamoto et al. (2005) reported the manifestation of Es layer (at mid-latitudes) with double layered structure which was due to ion accumulation by neutral wind shear. Scintillation activity associated with tropospheric convection-related gravity wave activity was reported using multi-instrument observations in the Indonesian sector (Ogawa et al., 2006). Wust and Bittner (2006) found the evidence for the occurrence of non-linear resonant three wave interaction in wind data obtained by the rocket-borne foil-chaff cloud technique during the Dynamics Adapted Network for the Atmosphere (DYANA) campaign at Biscarrosse (44°N) in 1990. Trinh et al. (2018) globally studied the propagation of gravity wave into thermospheric altitudes using multiple satellite observations. The role of gravity wave winds in producing ionization convergence over magnetic equator has also been investigated by many workers. A one dimensional theory invoking electric fields generated due to gravity wave associated winds, to explain the stratifications observed in the evening and night time equatorial ionosphere was

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