Predictions of energetic particle radiation in the close Martian environment

Abstract

[1] Intense, prolonged solar flare activity during March 1989 was used to provide a retrospective scenario for predictions of associated interplanetary shocks and accompanying particle radiation at planet Mars. Shocks from five major flares were simulated to hit both the Earth and Mars during the interval 9-23 March 1989. The simulated scenario was provided by the Hakamada-Akasofu-Fry version 2 (HAFv.2) solar wind model. Since part of the generally required inputs for the model (specifically metric radio Type II coronal shock speeds) were not available, the shock speeds were iteratively determined via a ''calibration'' that uses limited IMP 8 particle and sudden storm commencement (SSC) data as proxies for shock arrival at the Earth. The shocks from four major solar flares were, thereby, found to arrive at Mars at times that are appropriate to explain solar energetic particle (SEP) and energetic storm particle (ESP) events recorded in situ by the particle radiation detector experiments Solar Low Energy Detector (SLED) and Low Energy Telescope (LET) aboard Phobos-2. Supporting measurements were provided by the magnetometer (MAGMA) and plasma spectrometer (TAUS) experiments. A gap in the spacecraft records occurred at the simulated time of arrival of the fifth flare-associated shock. There were some uncertainties attending the selection of certain of the events deemed to be ''parent'' flares. Such uncertainty can be expected in view of the incomplete set of energetic particle, plasma, and magnetic field measurements made at relevant times at both the Earth and Mars (the latter planet was then located at a distance of 1.6 AU, at about 78°east of the Sun-Earth line). Use of the HAFv.2 solar wind model affords a 4-day lead time between predicted and measured space weather events at Mars, with an error of approximately ±12 hours. Solar radiation events of the magnitude studied occur often enough to warrant consideration in the design of both manned and unmanned expeditions to Mars.

Estimating the solar wind conditions during an extreme geomagnetic storm: a case study of the event that occurred on March 13–14, 1989

“…According to Cliver et al (1990), the solar flare associated with the first SSC of this storm event was identified as the March 10 X4.5/3B flare, which is in the top row of Table 1. McKenna-Lawlor et al (2005) also calculated an interplanetary shock propagation by using the HAFv2 model with the solar origin of the X4 flare on March 10 and the first SSC of the storm on March 13-14. The transit time from the occurrence of the solar flare to the first SSC in this event has been estimated to be 54.8 h, which is 3.8 times longer than the event on that occurred on August 4, 1972, with a transit time of 14.6 h (Cliver et al 1990).…”

“…For example, an extreme storm that occurred on March 13-14, 1989, which is the focus of this paper, had no solar wind coverage during its onset, main phase, and most of the recovery phase. Therefore, McKenna-Lawlor et al (2005) attempted to reconstruct the interplanetary shocks from five major flares hitting both Earth and Mars during the March 9-23, 1989, by using the HakamadaAkasofu-Fry version 2 (HAFv.2) solar wind model (Fry et al 2001(Fry et al , 2003. Other papers have reconstructed solar wind parameters during large storms by using geomagnetic variations or indices (e.g., Li et al 2006;Cliver et al 2009).…”

Energetic particles detected by the Electron Reflectometer instrument on the Mars Global Surveyor, 1999–2006

“…Relatively unmagnetized bodies such as Mars do not possess a coherent magnetosphere and thus their ionospheres are relatively unshielded from space weather events, which likely lead to interactions deeper in the atmosphere than for magnetized bodies Leblanc et al, 2002]. Previous work examining the impact of solar events at Mars includes characterization of shocks associated with large flares in March of 1989 using data from Phobos-2 [Aran et al, 2007;McKenna-Lawlor et al, 2005]. More recently, Zeitlin et al [2010] summarized solar particle events and galactic cosmic rays (GCRs) recorded by several instruments on Mars Odyssey between 2002 and 2006.…”

“…The timing and spatial properties of SEPs are also of interest, given their propensity to arrive suddenly after the onset of solar events. The impact of extreme space weather at Mars is an area of emerging and active research [Falkenberg et al, 2011a;Falkenberg et al, 2011b;McKenna-Lawlor et al, 2008;McKenna-Lawlor et al, 2005]. Relatively unmagnetized bodies such as Mars do not possess a coherent magnetosphere and thus their ionospheres are relatively unshielded from space weather events, which likely lead to interactions deeper in the atmosphere than for magnetized bodies Leblanc et al, 2002].…”

A statistical study of the performance of the Hakamada-Akasofu-Fry version 2 numerical model in predicting solar shock arrival times at Earth during different phases of solar cycle 23

“…For further details see Hakamada and Akasofu (1982), Sun et al (1985) and Fry et al (2001). It is noted that the model has also shown success in predicting shock arrivals at Mars and Venus (McKenna-Lawlor et al, 2005 and this predictive capability is presently being tested using improved statistics.…”