NASA into deep planning for Asteroid Redirect Mission
NASA has completed a review of its upcoming, first-of-its-kind Asteroid Redirect Mission (ARM) flight. ARM, scheduled to launch in 2021, will see the agency attempt to retrieve a boulder from the surface of a Near Earth Asteroid, place that boulder into lunar orbit, and test a potential planetary defense capability.
NASA is now deep into the planning phase for its highly-anticipated mission to redirect a portion of an asteroid into lunar orbit.
The mission will help demonstrate much-needed technologies for the eventual placement of humans on the surface of Mars and keeps with NASA’s current strategy to produce a phased approach to all major aspects of the agency’s in-space objectives.
To this end, ARM consists of a three-pronged mission alignment strategy.
The first phase began two years ago in 2014 with the commencement of the Asteroid Identification Segment of the mission architecture.
The second phase will consist of the Asteroid Redirect Robotic Mission spanning a total of 5 years before the third portion of the mission, the Asteroid Redirect Crewed Mission takes hold in 2026.
Phase 1: Asteroid Identification Segment
The first and obvious part of the ARM architecture is the identification and selection of the target asteroid for this first-of-its-kind mission.
This phase of ARM began in 2014 using space-based and ground-based telescope assets to scan the sky for Near Earth Objects (NEOs) – part of the NEO WISE project – that could pan out to be suitable Near Earth Asteroids (NEAs).
While this segment of ARM will continue through 2016 and 2017 under the ATLAS (Asteroid Terrestrial-impact Last Alert System) program banner, final selection of the ARM target is not anticipated until the end of 2020 or the beginning of 2021.
Nonetheless, NASA is working with four current Candidate Parent Asteroids for ARM, including Itokawa, Bennu, 2008 EV5, and 1999 JU3.
Specifically, Itokawa was previously visited by the Hayabusa probe from JAXA in 2005, is an S-type asteroid with a spin period of 12.13 hours, an aphelion of 1.7 AU, and an overall size of 535 x 294 x 209 m.
Bennu, the target of NASA’s upcoming OSIRIS-REx mission (scheduled to launch in September 2016 and arrive at Bennu in August 2018) is a B (C-grp volatile rich) asteroid with a spin period of 4.297 hours, an aphelion of 1.36 AU, and a size of 492 x 508 x 546 m.
Likewise, asteroid 1999 JU3 is the target of the in-progress Hayabusa 2 mission (which launched on 4 December 2014 and is scheduled to arrive at 1999 JU3 in July 2018), is a C-type (volatile rich) asteroid with a spin period of 7.627 hours, an aphelion of 1.42 AU, and a diameter of 870 m.
While all three of these asteroids are viable targets, NASA’s keen interest at the moment – and the candidate to beat – lies with asteroid 2008 EV5.
Asteroid 2008 EV5 is a C-type (volatile rich) asteroid with a spin period of 3.725 hours, an aphelion of 1.04 AU, and a total size of 420 x 410 x 390 m.
While 2008 EV5 is a candidate target destination for the European Space Agency’s (ESA’s) Marco Polo-R sample return mission, no mission is currently slated to visit the asteroid.
Consequential to Marco Polo-R target selection, radar imaging of 2008 EV5 strongly suggests the presence of boulders as well as a “pronounced bulge at the equatorial region suggesting movement of loose material” on its surface, states the recent ARM Update to the NAC Human Exploration and Operations Committee presentation.
Moreover, there is “Significant interest from the science and small bodies communities with well-documented investigation opportunities [for this] primitive, C-type (carbonaceous)” asteroid.
Phase 2: Asteroid Redirect Robotic Mission
Under the second phase of the ARM architecture, NASA will task a spacecraft with flying to, rendezvousing with, and characterizing an NEA – before retrieving a boulder from its surface and placing that boulder into a Distant Retrograde Orbit (DRO) of the moon.
For this Asteroid Redirect Robotic Mission (ARRM), an Asteroid Redirect Vehicle (ARV) will perform numerous objectives once it arrives at its designated target.
To accomplish this, NASA is examining ways to leverage commercially available capabilities for the spacecraft itself.
The ARM presentation notes that “The acquisition strategy for the ARRM spacecraft leverages existing commercially available U.S. industry capabilities for a high power Solar Electric Propulsion (SEP) based spacecraft.”
This SEP strategy will help align the U.S. commercial spacecraft industry with future needs for SEP technology for NASA’s human Mars mission campaigns in the coming decades and will help reduce costs and the overall cost exceedance risk to the ARV.
For the procurement of the ARV, NASA will employ a two-phase competitive process, including a Phase 1 study of four spacecraft designs, which is currently in progress, and a Phase 2 competition for the “development and implementation of the flight spacecraft bus by one of the study participants,” states the ARM presentation.
The four companies selected for competition in Phase 1 are Lockheed Martin Space Systems, Boeing Phantom Works, Orbital ATK, and Space Systems/Loral.
However, quite importantly for the ARV will be the capture system it will use to retrieve a boulder from the surface of the target asteroid.
Under the current prototype design, the ARV will use both a three-armed securing structure and a robot arm with a specially-designed grip to grab hold of a boulder on the surface of the NEA before gently lifting it off the asteroid and bringing it to the moon’s orbit.
Currently, a prototype contact and restraint system is under development by teams at the Langley Research Center, where they have accepted delivery of a full scale welded metal prototype and have completed flat floor testing of landing, extraction, and ascent operations.
Likewise, capture system prototyping and testing is ongoing at the Goddard Space Flight Center, while a new microspine gripper to be affixed to the end of the robot “capture” arm is under development at the Jet Propulsion Laboratory.
Moreover, in addition to the ARM phase 2 requirement, part of the ARV will include components for the third phase of ARM that will see a crew visit the captured boulder in lunar orbit.
These Phase 3 components will include a mission kit, consisting of a Passive International Docking Standard System compliant docking mechanism, EVA handrails and boom attachment points, common AR&D sensors, S-Band comm, and an EVA tool box complete with tools.
Phase 3: Asteroid Redirect Crewed Mission
All of this will set the stage for the third phase of the ARM project, the Asteroid Redirect Crewed Mission (ARCM) of an Orion vehicle to the boulder placed into lunar orbit.
According to the ARM presentation, this flight is targeted for 2026 – placing it notionally as the EM-5 mission (based on EM-2 in 2023 and a once-per-year flight rate of Orion thereafter) – and would be a 24.3 day, 2-person crewed mission launched aboard an Orion vehicle augmented with an ARCM mission kit.
This ARCM mission kit will include common AR&D sensors, EVA tools and translation aids, EVA communications equipment/capabilities, cabin repressurization capability, an active IDSS docking mechanism, EVA capable suits, exploration portable life-support systems, and suit servicing and recharge capabilities.
Including launch day objectives and the outbound transit, which will stretch over 12 days, the mission will then rendezvous and dock with the ARM robotic spacecraft in a 71,000 kilometer lunar DRO.
Orion and its two-person crew would then spend five days performing DRO operations, with two, 4-hour EVAs to “observe, document and collect asteroid samples” during the second and fourth days of DRO Ops.
Prior to the EVAs, the Orion spacecraft would perform a 20 degree yaw to “ensure proper EVA worksite thermal conditions and adequate space-to-ground communication coverage,” notes the ARM presentation.
Following DRO Ops, Orion would perform a Trans Earth Injection burn to begin the inbound transit back to Earth, culminating in an ocean landing after more than 24 days in space.
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