Outer Solar System Missions Research Articles

The Design of CubeSats for Outer Solar System Scientific Missions

In the past decade, CubeSats have emerged as a cost-effective solution for scientific missions beyond Earth’s orbit, though they have not yet gone further than orbiting Mars, as with NASA’s MarCO CubeSats. This paper discusses the technical challenges and solutions for designing CubeSats for Outer Solar System missions, specifically in the context of the proposed Astraeus Mission to Titan. These CubeSats, called the Mites, aim to measure heavy anions in Titan’s upper atmosphere and have undergone analysis to determine their optimal size and drag coefficient. A significant challenge addressed is the CubeSats’ power system, with solar panels being less effective at greater distances from the Sun. The paper proposes investigating Radioisotope Power Systems (RPS) as an alternative. However, there is the additional challenge of packaging the RPS in a sufficiently small form factor so that the upper atmospheric experiment can be completed. This must cover the greatest range of longitudes, latitudes, and ranges hence the orbital decay rate must be controlled to achieve this. The paper also explores the Mites’ long-duration exposure to space during transit and strategies to minimise cosmic radiation exposure. Whilst this is completed in the context of the Astraeus Mission, the data obtained can guide similar missions and aid others in overcoming the limitations of CubeSats so that they can be used more frequently for Outer Solar System science missions. Keywords: Titan, CubeSat, Radioisotope Thermoelectric Generator, Orbital Decay, Outer Solar System

Exploratory data analysis (EDA) machine learning approaches for ocean world analog mass spectrometry

Many upcoming and proposed missions to ocean worlds such as Europa, Enceladus, and Titan aim to evaluate their habitability and the existence of potential life on these moons. These missions will suffer from communication challenges and technology limitations. We review and investigate the applicability of data science and unsupervised machine learning (ML) techniques on isotope ratio mass spectrometry data (IRMS) from volatile laboratory analogs of Europa and Enceladus seawaters as a case study for development of new strategies for icy ocean world missions. Our driving science goal is to determine whether the mass spectra of volatile gases could contain information about the composition of the seawater and potential biosignatures. We implement data science and ML techniques to investigate what inherent information the spectra contain and determine whether a data science pipeline could be designed to quickly analyze data from future ocean worlds missions. In this study, we focus on the exploratory data analysis (EDA) step in the analytics pipeline. This is a crucial unsupervised learning step that allows us to understand the data in depth before subsequent steps such as predictive/supervised learning. EDA identifies and characterizes recurring patterns, significant correlation structure, and helps determine which variables are redundant and which contribute to significant variation in the lower dimensional space. In addition, EDA helps to identify irregularities such as outliers that might be due to poor data quality. We compared dimensionality reduction methods Uniform Manifold Approximation and Projection (UMAP) and Principal Component Analysis (PCA) for transforming our data from a high-dimensional space to a lower dimension, and we compared clustering algorithms for identifying data-driven groups (“clusters”) in the ocean worlds analog IRMS data and mapping these clusters to experimental conditions such as seawater composition and CO2 concentration. Such data analysis and characterization efforts are the first steps toward the longer-term science autonomy goal where similar automated ML tools could be used onboard a spacecraft to prioritize data transmissions for bandwidth-limited outer Solar System missions.

Compression algorithms for high-data-volume instruments on planetary missions: a case study for the Cassini mission

We investigated data compression algorithms to boost science data return from high-data-volume instruments on planetary missions, particularly outer solar system missions where every bit of data represents an engineering triumph of over severe constraints on mass (limiting antenna size) and power (limiting signal strength). We developed a methodology to (1) investigate algorithms to improve compression and (2) to work with the science teams to evaluate the effects on the science. Our algorithm for compressing the Cassini Radio Plasma Wave Science (RPWS) data achieved a factor of 5 improvement in data compression (relative to what the RPWS team was using), and our algorithm for the Cassini Ultraviolet Imaging Spectrograph (UVIS) Saturn data set achieved a much higher factor (∼70). In both cases, the investigators on the science teams who evaluated our results reported that the science goals were not compromised. Our compression algorithm for Imaging Science Subsystem images achieved on average a factor of ∼1.7 improvement in lossless compression compared to the original algorithm. We also evaluated the compression effectiveness of JPL’s Fast Lossless EXtended (FLEX) hyperspectral/multispectral image compressor on Cassini’s Visible and Infrared Mapping Spectrometer data. FLEX lossless compression provides a factor of 2 improvement over the original compression. We also explore a different range of lossy compression, which can achieve an additional factor 2 to 5 depending on the fidelity required. Our findings have implications for the design of future space missions, particularly with respect to antenna size and overall size, weight, and power budgets, by demonstrating strategies to implement better data compression. In addition to improved algorithms, we show that an iterative process involving real-time science team evaluation and feedback to update the onboard compression algorithm is both essential and feasible. We make the case that a spacecraft facility compressor hosting a toolbox of compression algorithms, available to all of the science instruments and supported by a team of compression experts, convey significant benefits. Beyond the obvious benefits of increased science return and faster playback, better data compression enables design trades between antenna size and number of science instruments on the payload.

Enabling a New Generation of Outer Solar System Missions: Engineering Design Studies for Nuclear Electric Propulsion

Enabling a New Generation of Outer Solar System Missions: Engineering Design Studies for Nuclear Electric Propulsion

A Reaction Drive Powered by External Dynamic Pressure

A new class of reaction drive is discussed, in which reaction mass is expelled from a vehicle using power extracted from the relative motion of the vehicle and the surrounding medium, such as the solar wind. The physics of this type of drive are reviewed and shown to permit high velocity changes with modest mass ratio while conserving energy and momentum according to well-established physical principles. A comparison to past propulsion methods and propulsion classification studies suggests new mission possibilities for this type of drive. An example of how this principle might be embodied in hardware suggests accelerations sufficient for outer solar system missions, with shorter trip times and lower mass ratios than chemical rockets. Keywords: Propulsion, Reaction drive, Solar wind, External power, Dynamic pressure

Operation of YBCO kinetic-inductance bolometers for outer solar system missions

We developed superconducting kinetic inductance bolometers (KIBs) for hyperspectral imaging in outer solar system missions. Each bolometer is a microwave L-C resonator that will act as an individual pixel in the focal plane of an imaging Fourier transform infrared spectrometer. Our devices are fabricated from high temperature superconductor yttrium barium copper oxide (YBCO), with a superconducting transition temperature of ∼85 K. The inductors are suspended on thin Si3N4 membranes. Each resonator operates at a unique resonant frequency, and hence, many can be multiplexed on a single feed line using a large number of carrier frequencies. The resonators function as detectors because their resonant frequencies decrease with increasing temperature as the bolometers absorb incident radiation. In this paper, we discuss the thermal properties of a YBCO KIB and its response to signal power to verify that the response is near theoretical predictions.

Cassini the grand finale

On 15 September, the Cassini space probe will burn up in Saturn's atmosphere, ending a 20-year voyage of scientific discovery. In this commemorative special we look at the wonders Cassini has seen, where it fits in the pantheon of outer solar system missions, and why its successors will be searching for one thing – life

Oral Histories in Meteoritics and Planetary Science – XX: Dale Cruikshank

Abstract– In this interview, Dale Cruikshank (Fig. 1) explains how as an undergraduate at Iowa State University he was a summer student at Yerkes Observatory where he assisted Gerard Kuiper in work on his Photographic Lunar Atlas. Upon completing his degree, Dale went to graduate school at the University of Arizona with Kuiper where he worked on the IR spectroscopy of the lunar surface. After an eventful 1968 trip to Moscow via Prague, during which the Soviets invaded Czechoslovakia, Dale assumed a postdoc position with Vasili Moroz at the Sternberg Astronomical Institute and more observational IR astronomy. Upon returning to the United States and after a year at Arizona, Dale assumed a position at the University of Hawai’i that he held for 17 years. During this period Dale worked with others on thermal infrared determinations of the albedos of small bodies beyond the asteroid Main Belt, leading to the recognition that low‐albedo material is prevalent in the outer solar system that made the first report of complex organic solids on a planetary body (Saturn’s satellite Iapetus). After moving to Ames Research Center, where he works currently, he continued this work and became involved in many outer solar system missions. Dale has served the community through his involvement in developing national policies for science‐driven planetary exploration, being chair of the DPS 1990–1991 and secretary/treasurer for 1982–1985. He served as president of Commission 16 (Physics of Planets) of the IAU (2001–2003). He received the Kuiper prize in 2006. Dale P. Cruikshank.image

Linear high resolution dust mass spectrometer for a mission to the Galilean satellites

The discovery of volcanic activity on Enceladus stands out amongst the long list of findings by the Cassini mission to Saturn. In particular the compositional analysis of Enceladus ice particles by Cassini's Cosmic Dust Analyser (CDA) (Srama et al., 2004) has proven to be a powerful technique for obtaining information about processes below the moon's ice crust. Small amounts of sodium salts embedded in the particles' ice matrices provide direct evidence for a subsurface liquid water reservoir, which is, or has been, in contact with the moon's rocky core (Postberg et al., 2009, 2011b).Jupiter's Galilean satellites Ganymede, Europa, and Callisto are also believed to have subsurface oceans and are therefore prime targets for future NASA and ESA outer Solar System missions. The Galilean moons are engulfed in tenuous dust clouds consisting of tiny pieces of the moons' surfaces (Krüger et al., 1999), released by hypervelocity impacts of micrometeoroids, which steadily bombard the surfaces of the moons. In situ chemical analysis of these grains by a high resolution dust spectrometer will provide spatially resolved mapping of the surface composition of Europa, Ganymede, and Callisto, meeting key scientific objectives of the planned missions. However, novel high-resolution reflectron-type dust mass spectrometers (Sternovsky et al., 2007; Srama et al., 2007) developed for dust astronomy missions (Grün et al., 2009) are probably not robust enough to be operated in the energetic radiation environment of the inner Jovian system. In contrast, CDA's linear spectrometer is much less affected by harsh radiation conditions because its ion detector is not directly facing out into space. The instrument has been continuously operated on Cassini for 11 years. In this paper we investigate the possibility of operating a CDA-like instrument as a high resolution impact mass spectrometer. We show that such an instrument is capable of reliably identifying traces of organic and inorganic materials in the ice matrix of ejecta expected to be generated from the surfaces of the Galilean moons. These measurements are complementary, and in some cases superior, compared to other traditional techniques such as infrared remote sensing or in situ ion or neutral mass spectrometers.

Planetary mission capability of small low power Solar Electric Propulsion systems

Planetary mission performance is presented for small, low power Solar Electric Propulsion spacecraft launched on a Delta II (7925) launch vehicle. The planetary missions presented in this paper are those that appear most attractive for a small, lowcost solar electric propulsion mission. These missions include comet and main belt asteroid rendezvous and high energy outer solar system flyby missions, all requiring a large ΔV commitment from the propulsion system. The outer solar system missions include solar probe missions using a Jupiter gravity assist and flyby missions to small outer solar system bodies. Included in this paper are examples of heliocentric transfer trajectories and estimates of performance for selected targets for each class of mission.