NASA’s Flexible Path evaluation of 2025 human mission to visit an asteroid
NASA managers have created an evaluation and roadmap for a potential human mission to visit the 1999 AO10 Near Earth Object (NEO) as early as 2025, as part of their options under the Flexible Path approach to the future of Human Space Flight. The mission would focus on using the International Space Station (ISS) as a testbed, with the ultimate focus on eventually heading to Mars.
NASA’s Human Mission to a Near-Earth Object (NEO):
The journey to an asteroid was originally classed as a potential stop-gap option between the end of the ISS’ active role and the eventual return to the moon, homing NASA’s skills in relearning human space travel out of Low Earth Orbit (LEO).
However, the internal 65 page Flexible Path presentation – available on L2 – presented several possible directions NASA may take under the Augustine Commission’s Flexible Path option, including the outlining of a NEO mission in the mid-2020s, a full five to six years after the original target date to return to the moon, as outlined in the Vision of Space Exploration (VSE) – which is no longer seen as achievable.
As with the option of setting up a number of large telescopes in LEO, Geostationary Orbit (GEO) and at the LaGrange points, joint missions between robotic and human missions highlight the NEO approach.
In the opening statements, the NASA authors decided to make references to the threat such NEOs pose – along with the fact a large amount of NEOs remain undiscovered – as an emphasis on supporting of such a mission.
“The first asteroid discovered was Ceres in 1801 by Giuseppe Piazz. By 1900, hundreds of asteroids were known, including the first NEO – Eros (signified by the red dot) discovered in 1898 by Carl Gustav Witt,” opened the section on the potential NEO mission.
“By 1950, ~2,000 asteroids had been discovered, including a number of ‘Earth crossers’ or NEOs. By 1990, >9,000 objects had been identified throughout the inner solar system. Within the decade a total of 86,000 objects had been cataloged.
“Today, ~500,000 minor planets are known. Of that number, ~6600 are NEOs; of that number ~1100 are PHOs.”
PHOs – or Potentially Hazardous Objects – are classed as objects that come within 0.05 AU (7.5 million km) of the Earth. PHOs are in orbits that have the potential to make close approaches to the Earth and of a size large enough to cause significant regional damage in the event of an impact.
Further information on the number of NEOs and PHOs will be forthcoming via “Next Generation Surveys such as LSST & Pan-STARRS, along with current on-going surveys, (which) expect to find many more NEOs and PHOs. The next generation surveys includes: Tracking (for better orbit determination). Characterization (taxonomy, minerals, volatiles, etc.). NEO-WISE is expected to find a few hundred NEOs in the next year.”
Based on the NEOs of interest – ones which are potential targets for a sending an expedition to visit – NASA has estimated 39 are accessible “based on a flight system assumptions consistent with a single Ares V-class launch.”
These targets have been generated from a list of NEOs already identified as accessible by human missions lasting up to a year, along with the viable outbound transit time for typical robotic missions to the same targets – resulting in multiple opportunities for human missions, and multiple opportunities also for precursor robotic missions in earlier years.
The scenario that was chosen for the purpose of the proposal to visit a NEO, targets the NEO “1999 AO10” – which holds three human launch opportunities in 2025, 2026 and 2032 – with three robotic precursor opportunities in 2019, 2020, or 2021.
“A robust example program can be constructed in which a human mission scheduled for launch in 2025 could withstand a one-year launch slip, while being preceded by a robotic reconnaissance precursor mission launched in 2019 that itself could withstand a one- or two-year launch slip,” added the presentation.
“In this ‘target rich’ mission space, NEOs afford diverse targets with many launch-year opportunities, varying mission durations, multiple opportunities to the same target, and multiple robotic precursor opportunities again to the same target.”
The Robotic Precursor Mission Scenario for 1999 AO10:
In NASA’s outline of the mission requirements, this target – and likely the case for other NEOs – would require the automated vehicle to arrive at the asteroid several years prior to the human expedition.
Such a robotic mission wouldn’t pose a problem for NASA engineers, who would follow a roadmap laid by the Hayabusa robotic mission, led by the Japan Aerospace Exploration Agency (JAXA) to return a sample of material from a small near-Earth asteroid named 25143 Itokawa.
Although not mentioned by name, one of the slides shows the robotic mission would be launched on either an Atlas V Heavy, and/or a Delta IV-Heavy, potentially in three modular stages, prior to rendezvous and docking in LEO ahead to the journey to the asteroid.
“Prior to sending a piloted mission to a NEO, additional characterization of the target is required. A typical robotic precursor would arrive at the designated NEO ~3 to 5 years prior to the corresponding human mission. This might be a Clementine/Hayabusa-class or Discovery class mission,” noted the presentation.
“Primary precursor mission instruments might include: high resolution optical camera system (surface identification, navigation, characterization, and mapping); LIDAR (topographical mapping, gravitational field survey, and shape modeling); visible and near-IR spectrometer (general compositional investigation); small lander/hopper (APXS, micrometeorite counter, dust collector, solar wind/particle collector, imager, radiometer, etc.)
“Mission objectives could include: Basic reconnaissance to assess potential hazards that may pose a risk to both vehicle and crew (as did Ranger, Lunar Orbiter, and Surveyor for Apollo), such as binary or ternary systems, rapid rotators, potentially active surfaces, etc.; and non-benign surface morphologies.
“Surface assessment for future activities to be conducted by human mission in order to maximize mission efficiency: proximity operations, surface operations, and sample collection. Preliminary determination of NEO target characteristics: surface morphology and properties (i.e., boulders vs. pebbles), gravitational field structure, rotation rate and pole orientation, mass/density estimates, general mineral composition.”
The robotic vehicle would also carry out the role of a guide and companion for the human mission, as depicted in a concept video (available on L2 – see slide) that shows Orion with the robotic vehicle in close attendance.
“Aid in the navigation of the piloted vehicle mission to the target NEO; provide additional data coverage during operations, obtain images of interactions of the crew and other assets at the NEO, supplemental examination of the NEO with additional sensors,” added the presentation on the role of the robotic vehicle prior, during and after the human mission.
“Monitor the NEO over time after crew and Orion vehicle depart; measure momentum transfer from kinetic/explosive experiment; image crater excavation processes/results (internal composition and structure); provide precise orbital measurements over a relatively long time period (e.g., better understand Yarkovsky and YORP effects).
“Relay data from science equipment left behind on the NEO by the crew: seismic stations, excavation/engineering equipment, resource extraction, etc.”
The Human Mission to 1999 A010:
For the scenario used by the Flexible Path presentation, a five to six month long duration flight is installed into the roadmap for the human expedition to the asteroid, and importantly is classed as a vital element of the overall mission – countering claims that robotics can carry out all the requirements of the mission on their own.
“A robotic precursor would have been conducted ~4 years prior to a human NEO mission. A typical piloted “sprint” mission would be ~155 days in duration,” continued the presentation.
“Instruments would include teleoperated rovers or hoppers (multiple trips to/from surface); multi-wavelength radar system (HGA could be used to perform radar tomography of the NEO to obtain internal structure); and small instrument packages for precision deployment by the crew during EVA or with a robotic rover system.
“The human crew would provide: adaptability and ingenuity to deal with complex issues in real time; direct interaction with the surface via a variety of methods; and wide-ranging E/PO activities including HD video of humans at another world.”
Again, the vehicles used in the presentation to transport the crew provides an interesting insight into NASA’s findings – following the Augustine Review – with no sign of Ares I being involved with the human transportation. Instead, a Human Rated Ares V is shown in the slide that illustrates the human launch element of the mission.
The mission scenario also provides further information of the roles for the crew once they arrive at the asteroid, noting a 14 day mission at the site, involving numerous EVAs to its surface.
“Mission objectives would include: Sample return: several macroscopic samples (10s to 100s of kg) from the surface, collected in geological context in different locations via multiple EVAs; supplemental robotic collection enhances sample return; collection of different or unusual samples from the surface (e.g., white rocks and black boulders on Itokawa),” added the presentation.
“Investigation of NEO interior characteristics; determination of internal structure (size scale and distribution of components); measurement of density and macroporosity of the NEO. Attachment of payloads to the surface for operation and subsequent retrieval. The NEO will have a microgravity regime, and possibly be a rubble pile with high porosity.
Roadmap from ISS to deep space experience:
The presentation continued by selling the viability of such a mission to a NEO, including references to the role the ISS could play in the planning stages, by utilizing the Station as a “first mission step” for a Deep Space Habitat simulation of the human missions.
“Exploration of NEOs can be decomposed into a series of logical steps that increment our knowledge of the object population, characterization of their diversity, in situ analysis via robotic missions, and culminate in human visits to one or more objects known by then to be worthy targets,” the presentation claimed.
“ISS utilization provides the first mission step, through which the NEO program would leverage existing ISSPO efforts in human health and performance, integrated system health management, advanced maintenance and servicing, and radiation shielding. ISS is a prime location to conduct an inhabited life test of the Deep Space Habitat.”
The NASA authors also make claims that these learning experiences would provide vital knowledge ahead of a Mars mission, which would follow a similar robotic to human roadmap.
“All human-mission NEO target candidates identified so far offer opportunities for robotic precursor visits while the human flight capabilities are being developed. Such early small-body investigations could include a NEO environment pathfinder, site characterization with sample science and sample return, and data collection to enhance NEO modeling.
“Next would come a human system precursor flight, which via vehicle system performance testing would demonstrate deepspace and autonomous operations, automated rendezvous and docking, high bandwidth communications, radiation hardened avionics, relevant-environment reliability, and other key capabilities. In a Flexible Path program, many of these needs could be demonstrated on human missions for other purposes.
“NASA would then be ready to mount one or more exploration missions to NEOs of interest, fully demonstrating Mars mission risk reductions like the Deep Space Habitat, deep space human-scale propulsion, and human/robot interaction in unplanned environments. The science yield would include the contextual macroscopic sample-collection, interior structure, and hazard deflection objectives described earlier.”
In conclusion, the NASA authors are positive such a NEO mission is possible and more so viable. Although no dollar amounts are mentioned, the presentation claims this option would be less expensive than either a moon or Mars mission.
“Apart from unique human-enabled science – including return of macroscopic samples and in situ conduct of subsurface active seismology – that could occur, human NEO missions offer two special benefits that support Flexible Path objectives:
“They have the ‘lowest price of entry’ of any human exploration missions to natural bodies. Trip times range from a few months up to Mars-class, and thus can drive development and qualification of long-lived, deep-space human systems and propulsion. Yet they do not require landers, ascent vehicles, or full-up roving mobility systems or surface infrastructure.
“The NEO population is huge, expected to continue growing as discovery continues, and diverse. Each of these objects is a small world to explore. The recent history of robotic exploration of small bodies implies asteroids and expended comets hold many surprises in store, assuring significant scientific interest and public attention.”
Part 4 of the Flexible Path Presentation articles will focus on NASA’s Mars and Phobos mission proposals, which have undergone a serious realignment following the Augustine Commission findings.
Part 1: Battle of the Heavy Lift Launchers – Monster 200mt vehicle noted
Part 2: Manned mission to construct huge GEO and deep space telescopes proposed
L2 members: Documentation – from which the above article has quoted snippets – is available in full in the related L2 sections, now over 4000 gbs in size