We present the outcome of a mission concept study that designed a small atmospheric entry probe and examined the feasibility and benefit of a future multi-probe mission to Uranus. We call our design the Small Next-generation Atmospheric Probe (SNAP). The primary scientific objective of a multi-probe mission is to reveal spatial variability of atmospheric conditions. This article first highlights that not all measurements must be repeated by multiple probes; some quantities, notably the noble gas abundances and elemental isotopic ratios, are not expected to be variable, and thus need to be performed only by a single large Primary Probe. Our study demonstrates that, by focusing its measurements on spatially variable quantities including atmospheric vapor concentrations, thermal stratification and wind speed, a viable atmospheric probe design is realized with an entry system with 50-cm heatshield diameter and 30-kg atmospheric entry mass. As a case study, we present a detailed analysis of adding SNAP to a notional Uranus Orbiter with Probe mission, which launches in 2031 and arrives at Uranus in 2043, designed by the NASA-funded Science Definition Team study in 2017. We demonstrate that, with minimal changes to the notional carrier mission, a large Primary Probe and SNAP can be delivered to the winter and summer hemispheres to examine seasonal atmospheric variabilities, and transmit data to the Orbiter, which in turn relays the data to Earth. The additional maneuvers needed to deliver SNAP totals a Delta-V of 84 m/s, and consumes 43 kg of propellant. The addition of SNAP is expected to cost $79.5 million in FY2018 dollars; thus, our study demonstrates that a multi-probe mission can be implemented with a 4% cost increase relative to the $2.0 billion cost estimate of the notional mission designed by NASA’s Ice Giant Flagship Science Definition Team study reported in 2017. The SNAP design incorporates several technologies that are currently under development at various Technology Readiness Levels (TRL) between TRL = 4 and TRL = 6. In particular, our study recommends targeted technology development in Thermal Protection System materials, advanced batteries, and miniaturized instruments to enable and enhance future small atmospheric probes like SNAP.

中文翻译：

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支持未来多探测器任务的小型下一代大气探测器 (SNAP) 概念：天王星案例研究

我们展示了一项任务概念研究的结果，该研究设计了一个小型大气进入探测器，并检查了未来对天王星进行多探测器任务的可行性和益处。我们称我们的设计为小型下一代大气探测器 (SNAP)。多探测器任务的主要科学目标是揭示大气条件的空间变化。本文首先强调，并非所有测量都必须由多个探头重复；某些量，特别是惰性气体丰度和元素同位素比率，预计不会发生变化，因此只需要由一个大型初级探头执行。我们的研究表明，通过将测量重点放在空间变量上，包括大气蒸汽浓度、热分层和风速，一个可行的大气探测器设计是通过一个具有 50 厘米隔热罩直径和 30 公斤大气进入质量的进入系统实现的。作为案例研究，我们详细分析了将 SNAP 添加到由 NASA 资助的科学定义团队于 2017 年进行的研究设计的带有探测任务的名义天王星轨道飞行器任务中，该任务于 2031 年发射并于 2043 年抵达天王星。我们证明，只需对名义上的载体任务进行最小的更改，就可以将大型初级探测器和 SNAP 运送到冬季和夏季半球，以检查季节性大气变化，并将数据传输到轨道飞行器，然后轨道飞行器将数据转发到地球。提供 SNAP 所需的额外操作总计 Delta-V 为 84 m/s，并消耗 43 kg 推进剂。以 2018 财年美元计算，增加 SNAP 预计将耗资 7950 万美元；因此，