Engineering topics

Reeves, David M.

Publications and source records attributed to Reeves, David M..

13 records

NASA NTRS2018

Mega-Drivers to Inform NASA Space Technology Strategic Planning

The National Aeronautics and Space Administration (NASA) Space Technology Mission Directorate (STMD) has been developing a new Strategic Framework to guide investment prioritization and communication of STMD strategic goals to stakeholders. STMD’s analysis of global trends identified four overarching drivers which are anticipated to shape the needs of civilian space research for years to come. These Mega-Drivers form the foundation of the Strategic Framework. The Increasing Access Mega-Driver reflects the increase in the availability of launch options, more capable propulsion systems, access to planetary surfaces, and the introduction of new platforms to enable exploration, science, and commercial activities. Accelerating Pace of Discovery reflects the exploration of more remote and challenging destinations, drives increased demand for improved abilities to communicate and process large datasets. The Democratization of Space reflects the broadening participation in the space industry, from governments to private investors to citizens. Growing Utilization of Space reflects space market diversification and growth. This paper will further describe the observable trends that inform each of these Mega Drivers, as well as the interrelationships between them within STMD’s new Strategic Framework.

Grande, Melanie L.↗

NASA NTRS2018

Strategic Framework for NASA’s Space Technology Mission Directorate

In October 2016, NASA’s Space Technology Mission Directorate (STMD) began adopting a new strategic framework that focuses investment prioritization and communication on impacts, outcomes, and challenges. The structure of the framework has been modeled after one successfully pioneered by NASA’s Aeronautics Research Mission Directorate over the past five years, incorporating lessons learned and changes where appropriate. The Framework is driven by two major factors: (a) dialogue with the community and (b) analysis of the overarching trends shaping the course of civilian space research. These factors are captured in the Framework as Mega-Drivers, which represent major axes of change within the space industry and are characterized by a collection of industry trends and projections. In response to these Mega-Drivers, STMD has developed its understanding of the vision for the future of civilian space relative to STMD space research, captured in five Strategic Thrusts that represent the major lines of investment within STMD’s portfolio. Within each of these Strategic Thrusts, multiple measureable, community-level goals have been established that STMD chooses to pursue as part of a joint effort across the community. STMD chose these goals based upon their potential impact, refers to them as Outcomes within the Framework. These Outcomes are decomposed into the products and/or capabilities that will be delivered by STMD, represented in the framework as Technical Challenges. This paper will further describe the framework structure and the progress that has been in defining each of the above elements to date.

Earle, Kevin D.↗

NASA NTRS2017

Enhanced Gravity Tractor Derived from the Asteroid Redirect Mission for Deflecting Hypothetical Asteroid 2017 PDC

The Asteroid Redirect Mission (ARM) concept would robotically visit a hazardous-size near-Earth asteroid (NEA) with a rendezvous spacecraft, collect a multi-ton boulder and regolith samples from its surface, demonstrate an innovative planetary defense technique known as the Enhanced Gravity Tractor (EGT), and return the asteroidal material to a stable orbit around the Moon, allowing astronauts to explore the returned material in the mid-2020s. Launch of the robotic vehicle to rendezvous with the ARM reference target, NEA (341843) 2008 EV5, would occur in late 2021 [1,2]. The robotic segment of the ARM concept uses a 40 kW Solar Electric Propulsion (SEP) system with a specific impulse (Isp) of 2600 s, and would provide the first ever demonstration of the EGT technique on a hazardous-size asteroid and validate one method of collecting mass in-situ. The power, propellant, and thrust capability of the ARM robotic spacecraft can be scaled from a 40 kW system to 150 kW and 300 kW, which represent a likely future power level progression. The gravity tractor technique uses the gravitational attraction of a station-keeping spacecraft with the asteroid to provide a velocity change and gradually alter the trajectory of the asteroid. EGT utilizes a spacecraft with a high-efficiency propulsion system, such as Solar Electric Propulsion (SEP), along with mass collected in-situ to augment the mass of the spacecraft, thereby increasing the gravitational force between the objects [3]. As long as the spacecraft has sufficient thrust and propellant capability, the EGT force is only limited by the amount of in-situ mass collected and can be increased several orders of magnitude compared to the traditional gravity tractor technique in which only the spacecraft mass is used to generate the gravitational attraction force. This increase in available force greatly reduces the required deflection time. The collected material can be a single boulder, multiple boulders, regolith, or a combination of different material types using a variety of collection techniques. The EGT concept assumes that the ability to efficiently collect asteroid mass in-situ from a wide variety of asteroid types and environments is a future capability that will be developed and perfected in the future by the asteroid mining community. Additionally, it is anticipated that the mass collection would likely be performed by a single or multiple separable spacecraft to allow the SEP spacecraft to operate at safe distance from the asteroid.

Mazanek, Daniel D.↗

NASA NTRS2016

Asteroid Redirect Mission Proximity Operations for Reference Target Asteroid 2008 EV5

NASA's Asteroid Redirect Mission (ARM) is composed of two segments, the Asteroid Redirect Robotic Mission (ARRM), and the Asteroid Redirect Crewed Mission (ARCM). In March of 2015, NASA selected the Robotic Boulder Capture Option1 as the baseline for the ARRM. This option will capture a multi-ton boulder, (typically 2-4 meters in size) from the surface of a large (greater than approx.100 m diameter) Near-Earth Asteroid (NEA) and return it to cis-lunar space for subsequent human exploration during the ARCM. Further human and robotic missions to the asteroidal material would also be facilitated by its return to cis-lunar space. In addition, prior to departing the asteroid, the Asteroid Redirect Vehicle (ARV) will perform a demonstration of the Enhanced Gravity Tractor (EGT) planetary defense technique2. This paper will discuss the proximity operations which have been broken into three phases: Approach and Characterization, Boulder Capture, and Planetary Defense Demonstration. Each of these phases has been analyzed for the ARRM reference target, 2008 EV5, and a detailed baseline operations concept has been developed.

Reeves, David M.↗

NASA NTRS2016

Asteroid Redirect Mission (ARM) Formulation Assessment and Support Team (FAST) Final Report

The Asteroid Redirect Mission (ARM) Formulation Assessment and Support Team (FAST) was a two-month effort, chartered by NASA, to provide timely inputs for mission requirement formulation in support of the Asteroid Redirect Robotic Mission (ARRM) Requirements Closure Technical Interchange Meeting held December 15-16, 2015, to assist in developing an initial list of potential mission investigations, and to provide input on potential hosted payloads and partnerships. The FAST explored several aspects of potential science benefits and knowledge gain from the ARM. Expertise from the science, engineering, and technology communities was represented in exploring lines of inquiry related to key characteristics of the ARRM reference target asteroid (2008 EV5) for engineering design purposes. Specific areas of interest included target origin, spatial distribution and size of boulders, surface geotechnical properties, boulder physical properties, and considerations for boulder handling, crew safety, and containment. In order to increase knowledge gain potential from the mission, opportunities for partnerships and accompanying payloads were also investigated. Potential investigations could be conducted to reduce mission risks and increase knowledge return in the areas of science, planetary defense, asteroid resources and in-situ resource utilization, and capability and technology demonstrations. This report represents the FASTâ€"TM"s final product for the ARM.

Mazanek, Daniel D.↗

NASA NTRS2015

Enhanced Gravity Tractor Technique for Planetary Defense

Given sufficient warning time, Earth-impacting asteroids and comets can be deflected with a variety of different "slow push/pull" techniques. The gravity tractor is one technique that uses the gravitational attraction of a rendezvous spacecraft to the impactor and a low-thrust, high-efficiency propulsion system to provide a gradual velocity change and alter its trajectory. An innovation to this technique, known as the Enhanced Gravity Tractor (EGT), uses mass collected in-situ to augment the mass of the spacecraft, thereby greatly increasing the gravitational force between the objects. The collected material can be a single boulder, multiple boulders, regolith or a combination of different sources. The collected mass would likely range from tens to hundreds of metric tons depending on the size of the impactor and warning time available. Depending on the propulsion system's capability and the mass collected, the EGT approach can reduce the deflection times by a factor of 10 to 50 or more, thus reducing the deflection times of several decades to years or less and overcoming the main criticism of the traditional gravity tractor approach. Additionally, multiple spacecraft can orbit the target in formation to provide the necessary velocity change and further reduce the time needed by the EGT technique to divert hazardous asteroids and comets. The robotic segment of NASA's Asteroid Redirect Mission (ARM) will collect a multi-ton boulder from the surface of a large Near-Earth Asteroid (NEA) and will provide the first ever demonstration of the EGT technique and validate one method of collecting in-situ mass on an asteroid of hazardous size.

Mazanek, Daniel D.↗

NASA NTRS2014

Discrete Element Method Simulation of a Boulder Extraction From an Asteroid

The force required to pull 7t and 40t polyhedral boulders from the surface of an asteroid is simulated using the discrete element method considering the effects of microgravity, regolith cohesion and boulder acceleration. The connection between particle surface energy and regolith cohesion is estimated by simulating a cohesion sample tearing test. An optimal constant acceleration is found where the peak net force from inertia and cohesion is a minimum. Peak pulling forces can be further reduced by using linear and quadratic acceleration functions with up to a 40% reduction in force for quadratic acceleration.

Kulchitsky, Anton K.↗

NASA NTRS2014

Proximity Operations for the Robotic Boulder Capture Option for the Asteroid Redirect Mission

In September of 2013, the Asteroid Robotic Redirect Mission (ARRM) Option B team was formed to expand on NASA's previous work on the robotic boulder capture option. While the original Option A concept focuses on capturing an entire smaller Near-Earth Asteroid (NEA) using an inflatable bag capture mechanism, this design seeks to land on a larger NEA and retrieve a boulder off of its surface. The Option B team has developed a detailed and feasible mission concept that preserves many aspects of Option A's vehicle design while employing a fundamentally different technique for returning a significant quantity of asteroidal material to the Earth-Moon system. As part of this effort, a point of departure proximity operations concept was developed complete with a detailed timeline, as well as DeltaV and propellant allocations. Special attention was paid to the development of the approach strategy, terminal descent to the surface, controlled ascent with the captured boulder, and control during the Enhanced Gravity Tractor planetary defense demonstration. The concept of retrieving a boulder from the surface of an asteroid and demonstrating the Enhanced Gravity Tractor planetary defense technique is found to be feasible and within the proposed capabilities of the Asteroid Redirect Vehicle (ARV). While this point of departure concept initially focuses on a mission to Itokawa, the proximity operations design is also shown to be extensible to wide range of asteroids.

Reeves, David M.↗

NASA NTRS2014

Asteroid Redirect Robotic Mission: Robotic Boulder Capture Option Overview

The National Aeronautics and Space Administration (NASA) is currently studying an option for the Asteroid Redirect Robotic Mission (ARRM) that would capture a multi-ton boulder (typically 2-4 meters in size) from the surface of a large (is approximately 100+ meter) Near-Earth Asteroid (NEA) and return it to cislunar space for subsequent human and robotic exploration. This alternative mission approach, designated the Robotic Boulder Capture Option (Option B), has been investigated to determine the mission feasibility and identify potential differences from the initial ARRM concept of capturing an entire small NEA (4-10 meters in size), which has been designated the Small Asteroid Capture Option (Option A). Compared to the initial ARRM concept, Option B allows for centimeter-level characterization over an entire large NEA, the certainty of target NEA composition type, the ability to select the boulder that is captured, numerous opportunities for mission enhancements to support science objectives, additional experience operating at a low-gravity planetary body including extended surface contact, and the ability to demonstrate future planetary defense strategies on a hazardous-size NEA. Option B can leverage precursor missions and existing Agency capabilities to help ensure mission success by targeting wellcharacterized asteroids and can accommodate uncertain programmatic schedules by tailoring the return mass.

Mazanek, Daniel D.↗

NASA NTRS2013

Understanding the Lunar System Architecture Design Space

Based on the flexible path strategy and the desire of the international community, the lunar surface remains a destination for future human exploration. This paper explores options within the lunar system architecture design space, identifying performance requirements placed on the propulsive system that performs Earth departure within that architecture based on existing and/or near-term capabilities. The lander crew module and ascent stage propellant mass fraction are primary drivers for feasibility in multiple lander configurations. As the aggregation location moves further out of the lunar gravity well, the lunar lander is required to perform larger burns, increasing the sensitivity to these two factors. Adding an orbit transfer stage to a two-stage lunar lander and using a large storable stage for braking with a one-stage lunar lander enable higher aggregation locations than Low Lunar Orbit. Finally, while using larger vehicles enables a larger feasible design space, there are still feasible scenarios that use three launches of smaller vehicles.

Arney, Dale C.↗

NASA NTRS2012

Overview of a Preliminary Destination Mission Concept for a Human Orbital Mission to the Martial Moons

The National Aeronautics and Space Administration s Human Spaceflight Architecture Team (HAT) has been developing a preliminary Destination Mission Concept (DMC) to assess how a human orbital mission to one or both of the Martian moons, Phobos and Deimos, might be conducted as a follow-on to a human mission to a near-Earth asteroid (NEA) and as a possible preliminary step prior to a human landing on Mars. The HAT Mars-Phobos-Deimos (MPD) mission also permits the teleoperation of robotic systems by the crew while in the Mars system. The DMC development activity provides an initial effort to identify the science and exploration objectives and investigate the capabilities and operations concepts required for a human orbital mission to the Mars system. In addition, the MPD Team identified potential synergistic opportunities via prior exploration of other destinations currently under consideration.

Mazanek, D. D.↗

NASA NTRS2010

Analysis of Water Surplus at the Lunar Outpost

This paper evaluates the benefits to the lunar architecture and outpost of having a surplus of water, or a surplus of energy in the form of hydrogen and oxygen, as it has been predicted by Constellation Program's Lunar Surface System analyses. Assumptions and a scenario are presented leading to the water surplus and the revolutionary surface element options for improving the lunar exploration architecture and mission objectives. For example, some of the elements that can benefit from a water surplus are: the power system energy storage can minimize the use of battery systems by replacing batteries with higher energy density fuel cell systems; battery packs on logistics pallets can also be minimized; mobility asset power system mass can be reduced enabling more consumables and extended roving duration and distance; small robotic vehicles (hoppers) can be used to increase the science exploration range by sending round-trip robotic missions to anywhere on the Moon using in-situ produced propellants.

Santiago-Maldonado, Edgardo↗

NASA NTRS2008

Dual Mission Scenarios for the Human Lunar Campaign - Performance, Cost and Risk Benefits

Scenarios for human lunar operations with capabilities significantly beyond Constellation Program baseline missions are potentially feasible based on the concept of dual, sequential missions utilizing a common crew and a single Ares I/CEV (Crew Exploration Vehicle). For example, scenarios possible within the scope of baseline technology planning include outpost-based sortie missions and dual sortie missions. Top level cost benefits of these dual sortie scenarios may be estimated by comparison to the Constellation Program reference two-mission-per-year lunar campaign. The primary cost benefit is the accomplishment of Mission B with a "single launch solution" since no Ares I launch is required. Cumulative risk to the crew is lowered since crew exposure to launch risks and Earth return risks are reduced versus comparable Constellation Program reference two-mission-per-year scenarios. Payload-to-the-lunar-surface capability is substantially increased in the Mission B sortie as a result of additional propellant available for Lunar Lander #2 descent. This additional propellant is a result of EDS #2 transferring a smaller stack through trans-lunar injection and using remaining propellant to perform a portion of the lunar orbit insertion (LOI) maneuver. This paper describes these dual mission concepts, including cost, risk and performance benefits per lunar sortie site, and provides an initial feasibility assessment.

Saucillo, Rudolph J.↗