Atmospheric escape to space has played a decisive role in the history of mars atmosphere and habitability. Two of the most significant escape processes are a) pickup ION escape, where planetary…

This federal contract award was granted by the National Aeronautics and Space Administration (NASA) Shared Services Center to The Regents of the University of California, doing business as the University of California, Berkeley (UC Berkeley). The $407,119.50 grant is for research on the global patterns and total rates of heavy ion and sputtering escape from the Martian atmosphere. This work aims to address the limitations of single-spacecraft measurements and improve understanding of these atmospheric escape processes and their variability with solar wind conditions. The award does not have a set-aside designation. As a public research university, UC Berkeley has extensive experience conducting space physics and atmospheric science research for NASA and other federal agencies under both contracts and grants.

Atmospheric escape to space has played a decisive role in the history of mars atmosphere and habitability. Two of the most significant escape processes are a) pickup ION escape, where planetary neutrals are ionized, energized and swept away by the solar wind and b) sputtering escape, where ions are accelerated back into the atmosphere, colliding with neutrals and giving them sufficient energy to escape. Both processes have complex global structure and vary significantly with solar wind density and velocity and the interplanetary magnetic field (IMF). The maven mission has greatly improved our understanding of these processes over the last two years by providing measurements of these heliospheric drivers and of energy and angular distributions of planetary ions from its elliptical 4.5 hour orbit. However, these measurements are fundamentally limited by a single platform, in three major ways. First, a single spacecraft can sample only along its orbit track, blurring the lines between spatial and temporal variability in escape processes and providing only a very small slice of their dynamic global patterns. Second, typically at least an hour separates any measurement of escape from the most recent or the next measurement of the upstream solar wind (which is not sampled at all for ~30% of orbits due to orbital precession). In contrast, solar wind disturbances propagate through the martian magnetosphere in ~1 minute. Third, space weather events such as coronal mass ejections are relatively infrequent and come in a wide range of strengths and types. They are thought to cause large increases in both ION escape and sputtering escape, but this escape has never been measured except along a single orbit and so its global variability is presently unknown. These limitations, imposed by single-spacecraft measurements, have led to an incomplete picture of the global patterns of ION and sputtering escape at mars and hence to significant uncertainties in estimates of the total amount of atmosphere lost to these processes over time. For two decades, the study of the earth s magnetosphere has required multipoint measurements to answer its most fundamental questions. Similarly, we will only be able to understand the variability of, and physics underlying, ION and sputtering escape at mars with multiple spacecraft. Our primary scientific question will be: what is the global pattern and total rate of heavy ION and sputtering eacape at mars and how does IT vary with steady solar wind conditions and over the range of space weather disturbances? Our study will explore range of options for accomplishing this mission. We have identified a compact instrument payload consisting of a plasma ION sensor and a magnetometer, and will examine its accommodation on a 6U and 12U smallsat platform. We will also explore and compare mission profiles for their feasibility and ability to address our science questions, under several headings. First, we will explore the mission timeline and propulsion needs for different trajectories from earth to mars orbit, considering both dedicated launch and piggyback scenarios. Second, we will explore the range of coverage of ION and sputtering escape possible with, 2, 3 and 4 smallsats, with different types of elliptical orbit and how orbital precession affects coverage over time. Third, we will explore options for near-constant solar wind monitoring, by a dedicated smallsat in a long elliptical orbit or by judicious choice of orbits of all sats such that one is always upstream. For a limited number of mission profiles which achieve adequate science coverage over a full mars year and for which power and propulsion solutions close, we will characterize the mass, power, telemetry, operations complexity, and cost budgets. We anticipate that this concept study will yield a detailed and thorough smallsat mission concept that will guide NASA in the solicitation and selection of future smallsat opportunities.