Lander Mission Research Articles

Ma'adim Vallis, Mars: Insights into episodic and late-stage water activity from an impact crater

Alluvial fans, a form of sedimentary deposit reported on Mars, offer insight into the evolution and nature of fluvial activity on the planet. Additionally, the region's preserved mineralogy can also be used to study its hydrological history. In this context, we discuss the diverse geomorphology and mineralogy of an unnamed crater that formed on the eastern wall of Ma'adim Vallis, Mars. Ma'adim Vallis is an irregular-shaped, flat-floored valley incised due to the outflow of water from the Eridania basin. The rim of the unnamed crater is breached at multiple locations and it hosts an alluvial fan of an area ~ 50 km2. The CRISM spectral signatures show Mg-rich olivine and Mg-rich smectite. Mg smectite was plausibly transported through water or formed in situ while the underneath terrain was rich in Mg olivine. The crater retention age on the ejecta of the unnamed crater is 3.7 Ga which suggests that the crater likely formed during the Noachian-Hesperian period boundary or earlier. This unnamed crater probably witnessed the last episode of water activity in the Vallis, which was most likely fed by water overflowing from a resurged early Hesperian water activity in Eridania Basin. This study substantiates episodic, late- stage water activity in Ma'adim Vallis, and the unnamed crater formed on the floodplains of the Vallis providing an excellent opportunity for future landing missions to explore astrobiological significance of the region.

Towards In-Situ Geochemical Analysis of Planetary Rocks and Soils by Laser Ablation/Ionisation Time-of-Flight Mass Spectrometry

Spectroscopic instruments were a part of payloads on orbiter and lander missions and delivered vast data sets to explore minerals, elements and molecules on air-less rocky planets, asteroids and comets on global and local scales. To answer current space science questions, the chemical composition of planetary rocks and soils at grain scale is required, as well as measurements of element (isotope) concentrations down to the part per million or lower. Only mass spectrometric methods equipped with laser sampling ion sources can deliver the necessary information. Laser sampling techniques can reduce the dimensions of the investigated sample material down to micrometre scale, allowing for the composition analysis of grain-sized objects or thin mineral layers with sufficiently high spatial resolution, such that important geological processes can be recognised and studied as they progressed in time. We describe the performance characteristics, when applied to meteorite and geological samples, of a miniaturised laser ablation/ionisation mass spectrometer (named LMS) system that has been developed in our group. The main advantages of the LMS instrument over competing techniques are illustrated by examples of high spatial (lateral and vertical) resolution studies in different meteorites, terrestrial minerals and fossil-like structures in ancient rocks for most elements of geochemical interest. Top-level parameters, such as dimension, weight, and power consumption of a possible flight design of the LMS system are presented as well.

Fuel-Optimal Guidance for End-to-End Human-Mars Entry, Powered-Descent, and Landing Mission

This article investigates the fuel-optimal guidance problem of the end-to-end human-Mars entry, powered-descent, and landing (EDL) mission. It applies a unified modeling scheme and develops a computationally efficient new optimization algorithm to solve the multiphase optimal guidance problem. The end-to-end EDL guidance problem is first modeled as a multiphase optimal control problem with different dynamics and constraints at each phase. Via polynomial approximation and discretization techniques, this multiphase optimal control problem is then reformulated as a polynomial programming problem. By introducing intermediate variables and quadratic equality constraints, a polynomial program is equivalently converted into a nonconvex quadratically constrained quadratic program (QCQP). Then, a novel customized alternating direction method of multipliers (ADMM) is proposed to efficiently solve the large-scale QCQP with convergence proof to a local optimum under certain conditions on the algorithmic parameters. The fuel savings under the end-to-end human-Mars EDL guidance are verified by comparing to the fuel consumption using the separate phase guidance approach. Furthermore, the computational efficiency of the customized ADMM algorithm is validated by comparing to the state-of-the-art nonlinear programming method. The robustness of the customized ADMM algorithm is verified via extensive simulation cases with random initial conditions.

Vector Trajectory Method for Obstacle Avoidance Constrained Planetary Landing Trajectory Optimization

Considering the requirement of avoiding obstacles in different planetary landing missions, this article presents a generalized method dealing with the obstacle avoidance constrained landing trajectory optimization problem with vectorized strategy, i.e., vector trajectory method (VTM). By introducing a trajectory direction constraint with vectorized description, the character of the obstacle avoidance trajectory can be more specifically depicted. Moreover, by satisfying proper trajectory direction constraint, the lander’s particular performances, such as the observation to the target or probability of a safe flight, can be improved. To this end, the VTM and relevant theorem are first developed, revealing the relationship between the two aspects of obstacle avoidance constraint (i.e., distance constraint and trajectory direction constraint). Then, both aspects of constraints are uniformly transformed as the auxiliary angle magnitude constraint with the vectorized strategy, which significantly simplifies the solving procedure of obstacle avoidance constrained trajectory optimization problem. Finally, the proposed VTM is illustrated in detail through the examples with the planetary landing background of atmospheric entry and powered descent landing.

Development of novel crystal scintillators for lunar surface science

The development of novel crystal scintillators for a lunar landed mission near future is reported. On that mission, we aim to assess the radiation dose, biological effect, water, and other resources on the lunar surface. To accomplish this, a Lunar Vehicle Radiation Dosimeter (LVRAD) made up of several radiation detectors has been proposed. New scintillation crystals are being developed for neutron and gamma measurements. Stilbene and undoped LaCl3 crystal were selected for fast neutron/gamma spectrometers. The mutual combination of organic and inorganic detectors benefits from direct fast neutron detection via 35Cl(n, p)35S reaction as well as the good gamma resolution of LaCl3 and the high detection efficiency of stilbene. LaCl3 crystals with the diameter of 38.1 mm were grown by a homemade modified Bridgman furnace. For epithermal neutron spectrometer, 6LiI:Ag crystal was selected due to its pulse shape discrimination capability and highest detection efficiency in terms of size for both thermal and epithermal neutron among scintillation materials. Enrich 6LiI was purified using the zone-refining technique. The crystal was then grown by the same Bridgman furnace.

A discussion on the plausible role of ice streams in carving Martian outflow channels: Revisiting the earliest hypothesis by Lucchitta et al. (1981)

Linear, incised and usually an order of magnitude wider than the Martian valleys, the Martian outflow channels are scoured ground commonly displaying streamlined remnants of the pre-existing terrain. A recent study used an unprecedented dataset of the Martian valley networks to propose that most of the valley networks are a result of combined surface and subglacial runoff. This also prompts to revisit One of the earliest hypotheses that the ancient ice streams might have carved the Martian outflow channels. With an exceptional focus on Mars exploration planned during the next decades, it is important to assess the regional-scale geomorphic processes to better target the future landing and sample return missions.

Analyzing the Efficacy of Flexible Execution, Replanning, and Plan Optimization for a Planetary Lander

Plan execution in unknown environments poses a number of challenges: uncertainty in domain modeling, stochasticity at execution time, and the presence of exogenous events. These challenges motivate an integrated approach to planning and execution that is able to respond intelligently to variation. We examine this problem in the context of the Europa Lander mission concept, and evaluate a planning and execution framework that responds to feedback and task failure using two techniques: flexible execution and replanning with plan optimization. We develop a theoretical framework to estimate gains from these techniques, and we compare these predictions to empirical results generated in simulation. These results indicate that an integrated approach to planning and execution leveraging flexible execution, replanning, and utility maximization shows significant promise for future tightly-constrained space missions that must address significant uncertainty.

Maximizing Dust Devil Follow-Up Observations on Mars Using Cubesats and On-Board Scheduling

Several million dust devil events occur on Mars every day. These events last, on average, about 30 minutes and range in size from meters to hundreds of meters in diameter. Designing low-cost missions that will improve our knowledge of dust devil formation and evolution, and their connection to atmospheric dynamics and the dust cycle, is fundamental to informing future crewed Mars lander missions about surface conditions. In this paper we present a mission for a constellation of low orbiting Mars cubesats, each carrying imagers with agile pointing capabilities. The goal is to maximize the number of dust devil follow-up observations through real-time, on-board scheduling. We study scenarios where cubesats are equipped with a 2.5 degree boresight angle camera that accommodates twenty-one slew positions (including nadir). We assume a concept of operations where the cubesats autonomously survey the surface of Mars and can autonomously detect dust devils from their surface imagery. When a dust devil is detected, the constellation is autonomously re-tasked through an onboard distributed scheduler to capture as many follow-on images of the event as possible, so as to study its evolution. The cubesat orbits are propagated assuming two-body dynamics and the ground tracks and camera field of view are computed assuming a spherical Mars. Realistic inter-agent communication link opportunities are computed and included in our optimization, which allow for real-time event detection information to be shared within the constellation. We compare against a powerful “omniscient” oracle which has a priori knowledge of all dust devil activity to show the gap between predicted performance and the best possible outcome. In particular, we show that the communications are especially important for acquiring follow-up observations, and that a realistic distributed scheduling mechanism is able to capture a large fraction of all dust devil observations that are possible for a given orbit configuration, significantly outperforming a nadir-pointing heuristic.

Rationale and Proposed Design for a Mars Sample Return (MSR) Science Program.

Rationale and Proposed Design for a Mars Sample Return (MSR) Science Program.

An experimental study of the alteration of basalt on the surface of Venus

Characterizing the surface of Venus has been complicated by its thick atmosphere and caustic surface conditions (~470 °C, 90 bars). Several approaches, including the collection of spectral data, thermodynamic modelling, lander missions, and surface weathering laboratory experiments have progressed our view of what lies at the surface. However, surface-atmosphere interactions remain somewhat unconstrained and interpretations of the spectral data rely on an understanding of the surface-atmosphere alteration. We used a cold-seal pressure vessel apparatus pressurized with pure CO2 gas and both synthetic and natural glassy basalts specimens to simulate chemical weathering on the surface of Venus for a duration of two weeks. The extent of alteration was described from the surface of samples to depth using Rutherford Backscatter Spectroscopy (RBS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. We describe the alteration zones of reacted basalt specimens and report an enrichment of divalent cation species at the near surfaces of basalts; Ca2+ was enriched by ~5 wt% and Fe2+ was enriched by ~1–2 wt%. The enrichment at the near surface favors the production of iron (Fe) oxide(s) and carbonates on the surfaces, which form discontinuous coatings on all reacted samples in two weeks duration. Our results aid in the interpretation of radar emissivity data by constraining which alteration products should be present on the surface and suggesting timeframes necessary for their detection. Assuming that radar emissivity is able to discern weathered basalt, especially those dominated by carbonates and/or semiconducting minerals Fe oxide(s), our results suggest that basalts at Idunn Mons in Imdr Regio previously thought to be anywhere from 2.5 million to a few years old (Smrekar et al., 2010; D'Incecco et al., 2017; Filiberto et al., 2020; Cutler et al., 2020) could instead be as young as 65,000 years to 110,000 years depending on basalt type.

Resurfacing: An Approach to Planetary Protection for Geologically Active Ocean Worlds

The putative and potential ocean worlds of our solar system span the asteroid belt to the Kuiper Belt, containing within their icy shells past or present global saltwater oceans. Among these worlds, those bearing signs of present-day geologic activity are key targets in the search for past or extant life in the solar system. As the icy surfaces of these bodies are modified by geologic processes, landforms are erased and replaced through what is called “resurfacing.” To avoid contaminating sites for robotic spacecraft exploration, planetary protection requirements obligate missions to these ocean worlds to demonstrate a less than 10−4 probability of introducing a viable terrestrial microorganism into a liquid water body. To constrain the probability of subsurface contamination, we investigate the interaction with geologic resurfacing on an active ocean world. Through the example of Europa, we show how the surface age can be used to constrain the resurfacing rate, a critical parameter to estimate the probability that nonsterile spacecraft material present on the surface is geologically incorporated into the subsurface, and extend this example to mission scenarios at Ganymede and Enceladus. This approach was critical to demonstrating compliance with planetary protection requirements for the Europa Clipper mission, reducing its probability of contamination by two to five orders of magnitude. We also show how a Europa lander mission might be brought close to complying with planetary protection requirements, that a Ganymede impactor could easily comply, and that the situation of Enceladus, while more complex, can greatly benefit from this approach.

Sediments Within the Icy North Polar Deposits of Mars Record Recent Impacts and Volcanism

AbstractThe North Polar Layered Deposits (NPLD) of Mars are ice‐rich sedimentary layers that formed under the influence of Mars' modern climate and thus record the recent climatic history of Mars, analogous to terrestrial ice sheets. The 2013–2023 Planetary Science Decadal Survey recommends a lander mission to sample the NPLD for climatic records; however, linking the geologic record to the climatic history will require quantitative dating of the NPLD. In this study we use orbital reflectance spectroscopy to show for the first time that dateable mafic lithics are present throughout the NPLD. We find significant glass as well as diverse crystalline minerals, which suggests that surface processes like impacts and volcanism were active during the late Amazonian and transported sediments from across the planet to the north pole. In situ investigation of the NPLD will thus provide critical quantitative constraints on both the recent geologic and climatic histories of Mars.

A fast and robust surface sample acquisition system for a Venus lander

JPL and Honeybee Robotics have designed, built and successfully tested a fast end-to-end sample acquisition and transfer system for the Venusian surface. This full scale prototype system uses a rotary-percussive drill designed to penetrate to a 5 ​cm depth in saddleback basalt in 15 ​min under full Venus surface conditions of 470 ​°C and 92 ​bar pressure and supercritical CO2 atmosphere. The drill features a hollow bit that collects particulate samples created during the drilling process. Sample transfer from drill to lander is done pneumatically using the motive force provided by the high pressure Venus atmosphere to entrain the particles in a high density flow. A cyclone particle separator removes the particles from the flow inside the lander and deposits them into an airlock, while the gas itself flows into a low pressure dump tank. Two samples are provided from the drill, one near the surface and one at 5 ​cm depth. Cross contamination between the near surface and at depth samples is minimized by collecting, but not analyzing, a third sample in between the two primary samples. The airlock is designed to depressurize and cool the particulate samples and then present them to science instruments for composition analysis. The entire drilling and sample transfer process completes in 30 ​min, thereby allowing it to support almost any kind of future short duration Venus lander mission. Results are presented for the first end-to-end drilling and sample transfer experiment conducted in a new specialized test chamber that replicates Venus surface conditions.

Science Goals and Mission Concept for a Landed Investigation of Mercury

Abstract Mercury holds valuable clues to the distribution of elements at the birth of the solar system and how planets form and evolve in close proximity to their host stars. This Mercury Lander mission concept returns in situ measurements that address fundamental science questions raised by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission’s pioneering exploration of Mercury. Such measurements are needed to understand Mercury's unique mineralogy and geochemistry, characterize the proportionally massive core's structure, measure the planet's active and ancient magnetic fields at the surface, investigate the processes that alter the surface and produce the exosphere, and provide ground truth for remote data sets. The mission concept achieves one full Mercury year (∼88 Earth days) of surface operations with an 11-instrument, high-heritage payload delivered to a landing site within Mercury's widely distributed low-reflectance material, and it addresses science goals encompassing geochemistry, geophysics, the Mercury space environment, and geology. The spacecraft launches in 2035, and the four-stage flight system uses a solar electric propulsion cruise stage to reach Mercury in 2045. Landing is at dusk to meet thermal requirements, permitting ∼30 hr of sunlight for initial observations. The radioisotope-powered lander continues operations through the Mercury night. Direct-to-Earth communication is possible for the initial 3 weeks of landed operations, drops out for 6 weeks, and resumes for the final month. Thermal conditions exceed lander operating temperatures shortly after sunrise, ending operations. Approximately 11 GB of data are returned to Earth. The cost estimate demonstrates that a Mercury Lander mission is feasible and compelling as a New Frontiers–class mission.

Titan's surface bearing strength: Contact force models for the Dragonfly rotorcraft lander

The bearing strength of surface materials expected in the Dragonfly's area of operations on Titan is considered, in order to inform landing dynamics simulations and define the required skid or footpad area of landing gear. In the hard limit, solid ice surfaces are practically unyielding and touchdown kinetic energy must be absorbed by the legs and structure. The soft limit corresponds to airfall organic dust on Titan, and defines the required foot area. As in previous lunar, Mars and comet lander missions, the strength estimate for ‘soft’ granular material (here ​∼ ​9 ​kPa for contingencies, and ∼20 ​kPa for nominal operations) is derived from the Terzaghi soil mechanics formalism, taking Titan material properties and gravity into account. A friction coefficient range of 0.1–0.75 is indicated from the literature on polymers and ice. A novel surface specification needed for Dragonfly is an adhesion term which defines the additional thrust (beyond weight) needed to takeoff in the event of sticky or muddy terrain. Laboratory data on slurries of grains in organic liquids, and analogs from the food industry, support a value of 3 ​kPa. Specifications on previous missions, and the terrestrial experience with skis and skids on aircraft, are reviewed for context.

Geomorphic map and science target identification on the Shackleton-de Gerlache ridge

Analogous to similar maps prepared in support of the Apollo missions, we produced a geomorphic map at a scale of 1:8000 of Artemis III Areas of Interest 001 and 004 on the Shackleton-de Gerlache ridge and the adjacent Shackleton crater rim to support future landed missions in the area. Using 1 m/pixel Lunar Reconnaissance Orbiter Narrow Angle Camera mosaics and 5 m/pixel topographic maps derived from Lunar Orbiter Laser Altimeter observations, we differentiated among ten units, all related to slope-controlled regolith processes or impacts, as well as among seven crater classes according to degradation state. Almost 85% of the map area outside of Shackleton crater are characterized by “elephant hide” textures at different intensities, which are mostly a function of the local slope angle. No signatures of the Shackleton ejecta blanket or a nearby Tycho ejecta ray were found in the morphology and crater statistics of our map area. We did, however, identify a potential lobate scarp and expanded on block detections by previous authors. We used our map to devise three consecutive traverse sequences named “Safe”, “Extended”, and “Increased risk”, which are each focused on maximizing sample yield and diversity to meet scientific objectives, while maintaining defined safety parameters. The three traverse sequences travel across respective maximum slopes of 10°, 15°, and 16°, have lengths of 3.6 km, 11.9 km, and 11.4 km, and each pass within sampling range of several block occurrences. The second traverse sequence “Extended” ends at a location with a direct line of sight into Shackleton crater, which would enable high-resolution observations using secondary illumination. The third traverse sequence “Increased risk” would conclude by reaching what might be a degraded Shackleton impact melt pond inside an adjacent, highly degraded crater. However, this sequence includes challenging illumination conditions and slopes up to 16° that warrant further investigations and hazard assessment. It should not be attempted until after key science questions are addressed during the preceding two traverse sequences. Based on their sizes, locations, and minor to moderate coverages by regolith, we interpret at least some of the blocks along each traverse sequence to be crustal fragments ejected during the Shackleton event or Shackleton rim material ejected by smaller craters. Thus, multiple locations along each traverse sequence provide the potential to not only investigate the unique south polar regolith, possible age signatures from Tycho, and potential volatiles in local micro-PSRs, but also the ages of Shackleton and the South Pole-Aitken basin.

MEMS GC Column Performance for Analyzing Organics and Biological Molecules for Future Landed Planetary Missions

We present a novel, innovative approach to gas chromatography-mass spectrometry (GC-MS) based on micro-electro-mechanical systems (MEMS) columns that improve the current, state-of-the-art by dramatically reducing the size, mass, and power resources for deploying GC for future landed missions. The outlet of the MEMS GC column was coupled to a prototype of the MAss Spectrometer for Planetary EXploration (MASPEX) through a heated transfer line into the ion source. MEMS GC-MS experiments were performed to demonstrate linearity of response and establish limit of detection (LOD) to alkanes (organics), fatty acid methyl esters (FAMEs) and chemically derivatized amino acids (biological molecules). Linearity of response to each chemical family was demonstrated over two orders of magnitude dynamic range and limit of detection (LOD) values were single to tens (4–43) of picomoles per 1 μl injection volume. MEMS GC column analytical performance was also demonstrated for a “Mega Mix” of chemical analytes including organics and biological molecules. Chromatographic resolution exceeded 200, retention time reproducibility was << 1% RSD (majority ≤ 0.3%), and peak capacity values calculated to be 124 ± 2 over a 435 s retention time window. The 5.5 m MEMS column was also shown to be a suitable alternative to traditional commercial columns for use in comprehensive two-dimensional gas chromatography (GC × GC). Mass spectra collected from MASPEX showed close consistency with National Institute of Technology (NIST) reference mass spectra and were used for high confidence identification of all eluting analytes.

The InSight-HP3 mole on Mars: Lessons learned from attempts to penetrate to depth in the Martian soil

The NASA InSight lander mission to Mars payload includes the Heat Flow and Physical Properties Package HP3 to measure the surface heat flow. The package was designed to use a small penetrator - nicknamed the mole - to implement a vertical string of temperature sensors in the soil to a depth of 5 m. The mole itself is equipped with sensors to measure a thermal conductivity-depth profile as it proceeds to depth. The heat flow is calculated from the product of the temperature gradient and the thermal conductivity. To avoid the perturbation caused by annual surface temperature variations, the measurements need to be taken at a depth between 3 m and 5 m. The mole is designed to penetrate cohesionless soil similar in rheology to quartz sand which is expected to provide a good analogue material for Martian sand. The sand would provide friction to the buried mole hull to balance the remaining recoil of the mole hammer mechanism that drives the mole forward. Unfortunately, the mole did not penetrate more than 40 cm, roughly a mole length. The failure to penetrate deeper is largely due to a cohesive duricrust of a few tens of centimeter thickness that failed to provide the required friction. Although a suppressor mass and spring as part of the mole hammer mechanism absorb much of the recoil, the available mass did not allow designing a system that fully eliminated the recoil. The mole penetrated to 40 cm depth benefiting from friction provided by springs in the support structure from which it was deployed and from friction and direct support provided by the InSight Instrument Deployment Arm. In addition, the Martian soil provided unexpected levels of penetration resistance that would have motivated designing a more powerful mole. The low weight of the mole support structure was not sufficient to guide the mole penetrating vertically. Roughly doubling the overall mass of the instrument package would have allowed to design a more robust system with little or no recoil, more energy of the mole hammer mechanism and a more massive support structure. In addition, to cope with duricrust a mechanism to support the mole to a depth of about two mole lengths should be considered.

A fitness sharing based ant clustering method for multimodal optimization of the aircraft longitudinal automatic carrier landing system

With the flight envelope becoming larger and larger, the Automatic Carrier Landing System (ACLS) is becoming a complex large-scale system, and the corresponding control parameter design has been the most important key link to ensure the safety and flight quality of aircraft carrier landing missions. In this paper, a Fitness Sharing based Ant Clustering (FSAC) method is presented for use in multimodal optimization of the longitudinal ACLS and to reveal the hidden properties of the solution space. In doing so, first, the lattice rule based space sampling strategy is used to create the individual ant sequences. Then a fading memory fitness sharing function is applied to modify the clustering strategy and regroup the ants for multimodal optimization of the search space. An adaptive learning strategy is developed to dynamically adjust the search scope of the ant colony. Moreover, an online health monitor is used to replace the weak ants with new ones in a timely manner in order to keep robustness of the FSAC. Finally, the multimodal feasible solutions which are good candidates for the ACLS design are presented and the characteristics of the solution space are also analyzed. The result shows that many large solution sets are located at the bottom of the solution space, whereas on the upper side of the solution space, the number of feasible solutions decreases sharply. An F/A-18 model is used as a test bed and the simulations are carried out in various wind conditions to demonstrate the effectiveness and feasibility of the proposed method.

Temperatures of the Lacus Mortis Region of the Moon

AbstractOver 11 years of data acquired by the Diviner Lunar Radiometer Experiment instrument aboard Lunar Reconnaissance Orbiter have been compiled into a comprehensive data set of surface temperatures in the Lacus Mortis region which includes the landing ellipse of the Astrobotic Mission One lander mission. These data provide diurnal brightness temperatures at 128 pixels per degree (ppd) spatial resolution and 0.1 hr of local time resolution. From this data set, we highlight several features that display variations in radiative and thermophysical properties in the Lacus Mortis region and characterize the temperatures of the Astrobotic Mission One landing ellipse. We identify distinctly contrasting properties of materials in the walls of Bürg crater, hummocks of materials on the southeast margin of the mare basalts, and materials exposed or excavated by impacts. Additionally, we describe an exceptionally rocky fault scarp that predates the formation of Bürg crater suggesting the observed boulders are replenished on a timescale <1 Ga. Within the Astrobotic landing ellipse, temperatures are observed to range from ∼88 to ∼359 K with sunrise and sunset local times constrained to 5.8–6.3 hr and 17.8 and 18.1 hr respectively.