2024 Mars Sample Return Design Overview

Transcription

1 2024 Mars Sample Return Design Overview Andrew Hoffman Abstract Scheduled for two launches set during two consecutive launch windows with the first launch occurring in 2024, the landmark Mars Sample Return mission will address question of the ability of Mars to support life in the past. To accomplish this goal, this mission will study the traces of past water on Mars, with a focus on geologic changes. To do this, our objective is to collect samples from the surface of Mars and return them for analysis on Earth. In order to accomplish this objective, the Mars Sample Return mission will utilize advanced science instruments and collection tools on the surface of Mars to facilitate the identification and collection of scientifically distinct samples with a clear focus on leveraging the end point advantage of Earth based laboratories. A strong goal of avoiding cross contamination in the returned samples is also notably present through all aspects of the mission. Another strong focus has been on reducing cost by fulfilling multiple needs with similar hardware, to allow for parallel development and management. Delivering a complex, multi launch mission to Mars and back has several key challenges that have been derived from a strict set of requirements in order to facilitate mission success. Foremost among these are launch vehicle performance, robust communications ability including interfacing with existing Mars on orbit communications infrastructure, mass of the spacecraft, rover autonomy, propulsive capture ability, and surface durability for the extent of the mission timeframe. The Mars Sample Return mission proposal laid out in the document has been selected after careful review to satisfy these and other key requirements. Introduction The primary objective for the Mars Sample Return mission is to collect scientifically distinct samples and return them to Earth in order to determine more about the history of Mars, with an emphasis on its ability to support liquid water in the past, as well as provide a proof of concept for hardware effectiveness of the mission profile for a manned Mars launch. Further opportunities for observations of Mars geology, spectrometry, and further assessment of the Mars radiation environment will also be conducted on the surface.

2 Three mission launches will be conducted from Cape Canaveral Air Force Station in Florida during two Earth to Mars opportunities, with launch dates being in 2024 (9/26), and 2026 (11/15). The margin for each window is roughly one week before and after the listed dates, which afford enough time to satisfy mission contingencies. Arrival for the system launched during each window will occur approximately nine months after each launch. The main elements of the MSR mission consist of three flight systems, each with a distinct payload. The first launch will be conducted in mid September 2024, and will carry a Mars science rover equipped with the tools to identify and collect samples in preparation for return, as well as fulfill secondary scientific objectives afforded by the situation. The second and third launches will occur during the mid November opportunity in The first of the 2026 launches will carry a Mars Ascent Vehicle (MAV), a Rover 2 to facilitate sample reposition. The second 2026 launch will carry an Earth Return Vehicle (ERV) along with the necessary hardware to interface with the MAV in Mars orbit, and DV hardware to bring them back to Earth. It will also be equipped re enter Earth's atmosphere safely. Every possible part of the three flight systems will be identical hardware in order to leverage the cost saving benefits of a streamlined ConOps for ground, manufacturing, and support operations. Launch Phases The MSR mission will be conducted in three launches during two launch opportunities, with all launches and windows having similar characteristics. The launch opportunities will occur in mid September 2024, and mid November All launches will use an EELV Atlas V launch vehicle. This was chosen because of it s success in the MSL mission, and all launches will utilize the same launch vehicle to control costs relating to contracting, ground support, and launch preparation. This decision leaves some of the Trans Mars stages with slightly above normal surplus in DV, but this has been decided as acceptable. The selected launch windows meet the following high level mission requirements: At least two weeks of acceptable launch days in every window. The only corollary is that it may be difficult to launch both scheduled vehicles within the second window if both are not kept at a relatively high state of readiness prior. This is mitigated by parallel phases in the lifecycles of the second two launches. With regards to the second two launches, there is enough time available for each payload to be injected into a Trans Mars trajectory with minimal risk of interference between each launch. Less than four years between launch windows, due to rover longevity concerns.

3 First Launch Objectives The payload of the first launch in 2024 will consist mainly of a rover, Rover 1, with the ability to remain active for a duration of at least 550 Martian Sols, while identifying and collecting samples, as well as systems for DV correction enroute, and systems for propulsive capture ending in atmospheric descent. Rover 1 will land on a chosen site that shows evidence of liquid water in the past. With the landing of Rover 1 coming nearly two years before the launch of Rover 2, this will be an opportune chance to test the precision landing capabilities being developed for this mission with time for feedback to be incorporated into the design process of Rover 2. Rover 1 will be able to roam over a considerable distance during its time on Mars, and does not need to land in a strictly defined area. However, what we learn from landing near a specific site with an attempted precision landing in Holden Crater will be invaluable in meeting the mission objectives inherent in the second launch, which does require Rover 2 to be placed with precision. With this opportunity, we are confident that the Rover 1 will have significant freedom of movement when choosing samples, and where to store samples. The aim for Rover 1 during the time spent of the surface of Mars before the second and third launch payloads arrive in LMO is to collect a volume of scientifically valuable samples, including rock cores, dust, and other geological features. Rover 1 will then move all collected samples to a single location, in preparation for Rover 2 and MAV that will be the payload of launch two. Second and Third Launch Objectives In 2026, two launches will enable the injection of two payloads into a Trans Mars trajectory, less than two weeks apart, each with the necessary systems for DV correction enroute. The first payload will consist of Rover 2, a Sample Return Canister (SRC), and a Mars Ascent Vehicle capable of lifting the SRC to Mars orbit, along with systems for propulsive capture. The second payload will consist of an Earth Return Vehicle, with sufficient DV to rendezvous with the MAV in orbit, and perform an Earth return maneuver. It will also be able to return the SRC to the surface of Earth, after aerocapture and re entry. As the first payload nears Mars, it will begin propulsive capture ending in atmospheric descent. The MAV, which contains the SRC, and the Rover 2 are all contained in the same descent system, and will be landed together. While the Rover 2 will separate after landing, the MAV will remain at the landing site. Rover 2 will only be used to relocate samples collected by Rover 1 into the SRC. Once the samples are safely placed in the SRC, the Capsule will be welded closed, sealed until opened after sample recovery on Earth. Then, the MAV, containing the SRC, will launch into Mars orbit.

4 When the second payload approaches Mars about two weeks after the MAV reaches orbit, it will begin propulsive capture ending in a stable Mars orbit. Once there, it will rendezvous with the MAV and transfer the SRC. The ERV will then perform a burn to a Trans Earth trajectory. The ERV is equipped to handle atmospheric descent after it aerocaptures in Earth orbit. This begins the Sample Return Phase. Sample Return Phase The SRC will then re enter Earth s atmosphere, land under canopy, and be recovered. Even if the aerocapture fails to properly slow the ERV, the SRC has been designed to survive an uncontrolled atmospheric descent at terminal velocity on Earth, and remain uncompromised long enough to facilitate recovery. After a normal or contingency recovery, the SRC will be transported to a purpose built biosafe facility for further study, where it will be opened and the samples studied. The mission will then transition to the closeout phase, as seen in the Lifecycle section of this document.

5 Mission Lifecycle Schedule Lifecycle Overview The Mars Sample Return mission has been designed to be implemented in seven stages, ending at SRC recovery and lasting roughly fifteen years. Each stage contains several technical and programmatic reviews, and are gated by Key Decision Points. Each Phase is roughly defined by a Key Decision Point, listed in the phases below. The Phases of the project are divided as seen in the standard chart below, with specific mission definitions laid out below the chart. It is important to note that each launch has it s own separate Phases B, C, and D. The 2024 Launch Phase C begins in 2020, while the two launches scheduled for 2026 will begin Phase C in All launches will operate on the timeline as laid out below. The second two launches will progress in parallel stages. The dates below are for the 2024 launch. The 2026 launches operate on the same lifecycle, +2 years for each Phase after Phase C.

6 Pre Phase A Pre Phase A began in early 2013, and was used to study the viability of several proposals towards a Mars Sample Return Mission. Several proposals were considered, including a two launch mission with both launches occurring during the 2026 launch opportunity as well as a manned, single launch sample return mission. The determined mission has been laid out in this document, and was chosen for meeting several key challenges. Most importantly, it provided a great deal of versatility at every stage, with large margins of error and a focus on affordability that could not be ignored. Pre Phase A ends in early 2015, when a final mission design specification has been reviewed, passed, and agreed upon by the necessary committees. It also provides an opportunity to begin the Mission Concept Review, and important phase review that helps determine the overall architecture of the mission, to begin understanding high level Concepts of Operations for the mission. Pre Phase A requires the least funding of any of the phases, but staff and materials will begin to ramp up sharply in Phase A. The key decision point for this phase is a review of mission proposals. If one proposal is selected as viable, the project can continue to the next Phase. Phase A Phase A will begin in early 2015, and is expected to last for three years. Phase A will be key for re tooling hardware used in the MSL mission to meet MSR needs. This approach is extremely cost effective, especially in regards to the Sample Collection Rover. Phase A is also the most critical phase as it requires the development of entirely new technologies and systems, namely the Mars Ascent Vehicle and the Earth Return Vehicle. This phase also involves the System Requirements Review, a key review the evaluates what technologies will need to be created for the mission, and what technologies will need to be developed. It also explores what will need to be manufactured for the mission, and which labor will be direct or subcontracted and which partnerships to leverage. The Key Decision Point for this stage is an early assessment of the project completion timeline. If it is assessed that the mission will be able to meet the stipulated launch windows, the project moves forward. Figures of Merit are also developed during this stage. Phase B Phase B begins in 2018, and will last for roughly two years. In Phase B, technologies that need to be developed for the mission will begin to reach maturation, and the details of the selected mission design will see completion. Exact launch dates will be selected, as well as burn correction points and abort procedures. This stage also includes the Preliminary Design Review, a review that collates and confirms schedules, risk assessments, and technology maturity. The Key Decision Point for this stage has been determined to dependent on budget. If

7 the project is moving forward without significant cost overruns, the project continues. The developed Figures of Merit are also very important during this stage. Phase C Phase C begins in 2020, and will last until early Phase C is a largely procedural phase, and is characterized by the Critical Design Review, a review that aims to evaluate the current success of the project with an aim towards it s fulfillment of budget, schedule, and safety constraints. Phase C will see the fabrication of most of the spacecraft components for all stages and final negotiations with sub contracting partners. The Key Decision Point for this phase is preparation at this point, the mission should be nearly completed and ready to transition to Phase D. Figures of Merit are also consulted and are extremely important during this stage. Phase D It is important to note that there are three instances of Phase D, occurring during two separate launch opportunities. The first instance occurs during the launch window in 2024, the second two during the launch window in Phase D includes the critical stages of the final assembly of the components manufactured during Phase C, testing of the components, and eventually, the launch. The Phase lasts until the payload has been injected into a Trans Mars Trajectory. The Key decision point for this phase is this viability of each launch. Phase E Phase E is a critical phase in the MSR mission. It begins in late 2024, after the first payload is en route to Mars. During this phase, the critical steps of landing both rovers, sample collection, Mars ascent, Sample transfer, and others will be conducted. This is the main Phase for On Mars operations. Key decisions points for this Phase are varied, but include Sample Viability, Mars Ascent, and Trans Earth Injection. Figures of Merit are also considered. Phase F Phase F consists mainly of safely returning the SRC to a biosafe facility, studying the samples contained, and distributed the knowledge and data to the scientific community. There are no key decision points for this Phase, though Figures of Merit are still considered.

8 Below is a Work Breakdown Structure for the Mars Sample Return Mission. Figures of Merit/Performance When developing the Mars Sample Return mission, several figures of merit were used to evaluate the mission during phase transitions. The most important ones are listed here. 1. Sample collection variability. The Rover needs to be able to collect samples from several different sites, materials, and depths/stratas. 2. Launch Vehicle & cruise stage simplicity, repetition, and cost reduction. Using a single type of launch vehicle and cruise stage for all three payloads greatly reduces cost, and development time. 3. Sample Return Canister and collection cross contamination chances. The samples must be able to be returned to Earth, even in an uncontrolled re entry, with a minimal risk of cross contamination. 4. Overall cost of a system. Each system needs to be carefully screened for lower cost alternatives that can also fulfill the systems role adequately.

9 5. Additional Scientific value. Many systems will be spending a significant amount of time on or around Mars, and it needs to be considered that a small investment of mt and cost can be substantially rewarded at a later stage in the mission. Afterword My name is Andrew Hoffman, and I m starting college in August of this year. This course is the first I ve taken in relation to my interest in space, and the first Saylor course I have taken. I want to thank everyone involved with it tremendously, I really can t express the depth of my gratitude. Thank you all very much for all of the effort that went into this course. Unlike some of the other participants in the MSR project, I am not working in a team, nor do I have any experience with systems engineering or aerospace. Everything I know about this field comes from either this course, or what I ve learned following my own deep interest in the subject. I initially was not going to participate in this extra credit offering due to time constraints and, admittedly, being intimidated when I first read the documentation. However, as I proceeded in the course, I eventually decided to participate. Because of this, I have had less than three days to work on this project. Still, I really enjoyed it and I did my best.