arXiv subjects

Tarun Kumar Pant

Publications and source records attributed to Tarun Kumar Pant.

4 recordsLinked to original sources

arXiv2025

Loss of 12 Starlink Satellites Due to Pre-conditioning of Intense Space Weather Activity Surrounding the Extreme Geomagnetic Storm of 10 May 2024

This study investigates the orbital decay and subsequent reentries of 12 Starlink satellites from 16 April to 15 May 2024. By examining Two-Line Element data, we observed a significant increase in orbital decay following the geomagnetic storm on 10 May 2024, consistent with expectations of increased thermospheric density. An unexpected increase in decay rates for 10 satellites was identified around 25 April 2024, while two lower-altitude satellites remained unaffected. Detailed analysis revealed that this enhanced decay rate prior to the storm was influenced by a spike in the O/N2 ratio and an increase in Extreme Ultra Violet (EUV) flux. Moreover, most of the satellites exhibited sharp decay during the early recovery phase of the geomagnetic storm. Based on the positions and local times of changes in decay rates, it is likely that the satellites were affected by various processes during elevated space weather activity, such as enhanced EUV flux, Joule heating, particle precipitation, and the equatorial neutral anomaly. This study highlights the complex role of preconditioning due to enhanced EUV flux and extreme space weather activity in the orbital dynamics of Low-Earth Orbit (LEO) satellites.

physics.space-ph↗

arXiv2025

Deciphering Solar Cycle Influence on Long-Term Orbital Deterioration of Low-Earth Orbiting Space Debris

The rapid increase in the number of space debris represents a substantial threat to the sustained viability of space operations and underscores the importance of understanding long-term drivers of orbital decay. This first of its kind study examines the long-term impact of solar activity on the orbital decay of 17 LEO debris objects across Solar Cycles 22, 23, and 24 using Two-Line Element (TLE) data spanning these three cycles. Analysis of TLE-derived decay profiles, in conjunction with sunspot numbers (SSN) and F10.7 index, reveals a threshold: orbital decay rates increase sharply when SSN exceeds approximately 67-75% of its cycle peak. This threshold corresponds to enhanced thermospheric density driven by elevated solar input, resulting in increased atmospheric drag. The orbital decay rates at the peak of each solar cycle show a progressive decline from Cycle 22 to Cycle 24, mirroring the corresponding decrease in solar activity. Decay profiles for Solar Cycle 24, predicted using ballistic coefficients derived from TLE data during Cycles 22 and 23 and atmospheric densities from the MSIS 2.0 model, show strong agreement with observations after applying a scaling factor. However, two high-inclination objects exhibited significant deviations, highlighting limitations in the MSIS model's ability to represent atmospheric conditions at high latitudes. In contrast, lower-inclination objects showed excellent correspondence. Overall, the findings confirm solar-driven thermospheric variability as the dominant factor influencing long-term orbital decay and emphasize the need to refine atmospheric models-particularly for polar regions-to improve re-entry predictions and satellite mission planning.

physics.space-ph↗

arXiv2024

AuroraMag: Twin Explorer of Asymmetry in Aurora and Solar Wind-Magnetosphere Coupling

In the present-day context, small satellites and their constellations consisting of varying sizes (nano, micro, pico satellites) are being favored for remote sensing and in situ probing of the heliosphere and terrestrial magnetosphere-ionosphere system. We introduce a mission concept aimed at concurrently observing Earth's northern and southern auroral ovals while conducting in situ measurements of particles, fields, and temperature. The mission concept consists of two small satellites, each having an identical auroral X-ray imager, an in situ particle detector, a magnetometer pair, and an electron temperature analyzer onboard in an elliptical polar orbit (400X1000 km ). This mission would assist the space weather community in primarily answering important questions about the formation, morphology, and hemispherical asymmetries that we observe in the X-ray aurora, the fluxes of precipitating particles, Solar Energetic Particles, currents, and cusp dynamics. Once realized, this would be the first dedicated twin spacecraft mission of such kind to simultaneously study hemispheric asymmetries of solar-wind magnetosphere coupling. This study reveals the intricacies of the mission concept, encompassing orbital details, potential payloads, and its underlying scientific objectives. By leveraging the capabilities of small satellites, this mission concept is poised to make significant contributions to space weather monitoring and research.

physics.space-ph↗

arXiv2019

Acceleration of Energetic Ions in Corotating Interaction Region near 1.5 au: Evidence from MAVEN

The dearth of observations between 1 au and 3 au limits our understanding of energetic particle acceleration processes in interplanetary space. We present the first-of-their-kind observations of the energetic particle acceleration in a Corotating Interaction Region (CIR) using data from two vantage points, 1 au (near Earth) and 1.5 au (near Mars). The CIR event of June 2015 was observed by the particle detectors aboard the Advanced Composition Explorer (ACE) satellite as well as the SEP (Solar Energetic Particle) instrument aboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft situated near 1.5 au. We find that a CIR shock can accelerate a significant number of particles even at 1.5 au. During this event the acceleration by the shocks associated with the CIR could cause an enhancement of around two orders of magnitude in the SEP energetic ion fluxes in the ~500 keV to 2 MeV range when the observations near 1 and 1.5 au are compared. To demonstrate the differences between SEP acceleration in CIR and other impulsive events, we show the energetic ion flux observations during an intense CME period in March 2015, in which case the enhanced SEP fluxes are seen even at 1 au. These observations provide evidence that CIR shock can accelerate particles in the region between Earth and Mars, that is, only within the short heliocentric distance of 0.5 au, in interplanetary space.

physics.space-ph↗