NASA administrator Charlie Bolden has officially announced an ambitious mission to send a crew to a captured asteroid as early as 2021. Mission planning is scheduled to begin in the summer, with the potential to redefine the 2021 Exploration Mission -2 (EM-2) flight, involving the Space Launch System (SLS) and the first crewed Orion spacecraft.
Interest In Asteroids:
The announcement – made during the FY14 Budget Proposal overview – is part of President Obama’s vision of sending humans to a “Near Earth Asteroid (NEA)” by 2025, although it is vastly different to all the previous NASA studies relating to visiting a space rock.
While asteroid aspirations have been part of NASA discussions since the 1970s, mission planning has suffered from the ever-changing political direction that has curtailed the agency from sticking to a long-term exploration roadmap.
Back during the Vision for Space Exploration (VSE) days, NASA’s goal was to visit the “Moon, Mars and Beyond” – a roadmap that was designed to redirect NASA following the decision to retire the Space Shuttle fleet.
While it wasn’t classed as a priority, notional studies cited a journey to an asteroid as a potential stop-gap option, inserted in-between the end of the ISS’ active role and the eventual return to the Moon, honing NASA’s skills in relearning human space travel outside of Low Earth Orbit (LEO).
With NASA’s direction maturing into the Constellation Program (CxP), the goals became more focused on a return to the Moon’s surface – with the potential to set up a Lunar Base – before taking aim on the ultimate goal of Mars.
However, as CxP began to suffer from major schedule problems, a major alternative option was evaluated around the Augustine Commission’s review into NASA’s Human Space Flight plans.
Known as the “Flexible Path”, the expansive study finally provided hard details on potential NEA missions. The internal 65 page Flexible Path presentation – available on L2 – presented actual destinations for missions that would launch in the mid-2020s.
In the opening statements of the study, the NASA authors made strong references to the threat asteroids pose – along with the fact a large amount of NEOs remain undiscovered – as an emphasis on supporting of such a mission from an Earth protection standpoint.
“The first asteroid discovered was Ceres in 1801 by Giuseppe Piazz. By 1900, hundreds of asteroids were known, including the first NEO – Eros, discovered in 1898 by Carl Gustav Witt,” opened the section on the potential NEA missions.
“By 1950, ~2,000 asteroids had been discovered, including a number of ‘Earth crossers’ or NEAs. 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.
As far as potential NEAs to visit, the Flexible Path presentation pointed to a mission to Near Earth Object 1999AO10 as a candidate, requiring a mission launch date of January 2, 2026.
The NEO 1999AO10 deep space mission would last 155 days, around half of the mission length for the alternative candidate mentioned in the Flexible Path approach – 304 days – for NEO 2001 GP2.
Each mission allocated 14 days for the crew to conduct investigations and EVAs at the asteroid.
Tweaking The Current Plan:
NASA’s current Exploration Plan is mainly undefined, mainly due to uncertainty in the long term budget profile. However, the opening two missions for SLS and Orion have been documented via the CONOPS (Concept of Operations) and Design Reference Mission (DRM) presentations, as acquired by L2 and reported by this site.
The new SLS is currently targeting a debut launch in its Block 1 configuration in December, 2017, on what is known as Exploration Mission -1 (EM-1) – an uncrewed validation flight of the Heavy Lift Launch Vehicle (HLV) tasked with lofting Orion enroute to 7-10 day mission around the Moon.
The next mission currently manifested is for 2021, known as the EM-2 flight – a near-repeat of EM-1. However, for this flight, a crew of four will ride in Orion, venturing into Deep Space for the first time in decades.
The Design Reference Mission (DRM) documentation notes EM-2 to be a CLO (Crewed Lunar Orbit) flight, given the astronauts will spend three to four days orbiting our nearest neighbor, as opposed to heading directly home after passing around the Moon.
With the new asteroid mission officially scheduled for “as soon as” 2021, it is believed NASA planners will aim to take advantage of EM-2’s CLO profile, by “simply” adding the content of the asteroid rendezvous to the days the crew will spend near the Moon.
For the realigned EM-2, a 2019 mission is required to hunt down and capture the asteroid that would then be placed in the vicinity of the Moon within two years, a plan believed to be based around a proposal from the Keck Institute for Space Studies (KISS). A full mission outline article will be in the coming days.
The 2019 mission would require the launch of an Asteroid Retrieval Spacecraft (ARS) via an Atlas V in its 551 configuration, setting sail for an asteroid that would small enough and relatively close by.
The KISS approach notes such a mission could involve “between two and six years” – dependant on size and location of the asteroid.
This key parameters will determine the schedule, as NASA teams begin their hunt for a candidate asteroid. NASA managers will hold the option to move the mission further down the schedule, which would in return EM-2 back to its original plan.
Technology and Procedures Already To Hand:
With six years to go until the planned launch of the ARS, and potentially eight years until the launch of a realigned EM-2, the teams will be pushed hard to meet the challenge outlined in the FY14 Budget Proposal. However, a number of key technologies and mission procedures already exist.
For the ARS, the launch vehicle cited by the KISS approach is already available, along with the Solar Electric Propulsion (SEP) technology that would be used to send the ARS to rendezvous with the asteroid, prior to dragging it to a location – likely a Lagrange point – near the Moon.
Californian company Aerojet recently promoted the use of their current Solar Electric Propulsion technology as an enabler for NASA’s deep space aspirations – the same technology which enjoyed a staring role in the rescue of the Advanced Extremely High Frequency satellite (AEHF-1).
Despite a nominal launch atop of an Atlas V – incidentally aided by three of Aerojet’s strap on solid rocket boosters – in August, 2010, a failure of the satellite’s subsystem resulted in the AEHF-1’s hydrazine-fueled liquid apogee engine (LAE) failing to carry out the required burns to place it correctly into Geostationary Orbit.
Thanks to some clever work via the satellite’s United States Air Force controllers and AEHF-1 teams, the $2 billion bird was saved via the ingenious use of the two smaller engines – namely the hydrazine-fueled Reaction Engine Assemblies (REAs) and later by the xenon-fueled Hall Current Thrusters (HCTs) – despite their primary role being one of positional stability on orbit.
The HCT thrusters – small motors that use electricity and xenon gas as propellant – do not have a large thrust level, but sport some amazing stamina, allowing them to fire over and over again for thousands of times.
While these motors can look forward to providing positional stability for upcoming satellites, along with long-distance trips with deep space spacecraft – a role Aerojet’s electric propulsion has successfully carried out on a huge range of spacecraft – a potential marriage between SEP and NASA’s exploration missions is something Aerojet are more than happy to work on.
“We believe that Aerojet’s current Solar Electric Propulsion technology, such as that used to rescue AEHF, is immediately applicable to a key role in Human Space,” noted Julie Van Kleeck, Aerojet Vice President, Space & Launch System in an interview with NASASpaceflight.com.
Also, a large amount of training has already been conducted for when the astronauts meet the asteroid. This work has been conducted via the NASA Extreme Environment Mission Operations (NEEMO) missions, which took place at the Aquarius underwater habitat in Key Largo, Florida.
Although the training related to a full scale asteroid mission, including the use of habitats and a Multi Mission Space Exploration Vehicle (MMSEV), the protocols and procedures – including the use of NASA’s Mission Operations Directorate (MOD) – will provide mission planners with a very useful baseline.
For the proposed mission, the ARS will arrive at the asteroid, before deploying a giant telescoping “plunger” to capture and encase the space rock, with the pair then heading back to the designated area near the Moon.
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The Orion crew would then launch via the SLS and arrive at the ARS with its captured friend, allowing for the astronauts to conduct a short distance EVA.
Procedures for conducting EVAs from Orion have also been practised back in 2010, via a series of EVA egress/ingress tests on a full-scale mock-up of the Orion crew module in the large Neutral Buoyancy Lab (NBL) at the Johnson Space Center.
According to the Joint EVA NBL Orion Mockup (JENOM) test overview document – available for download on L2 – “The primary purpose of (Test 8 of the EVA Systems Project Office (ESPO)) (was) to understand the Orion design implementation for the side hatch and internal layout.
“The test (helped) provide information to the design teams (on) mobility needs, location of vehicle interface element umbilicals on the (EV) suit, and understanding of umbilical based operations in order to assist with design maturity.”
As outlined in NASA’s notional video of the asteroid mission, the crew would exit the Orion via the side hatch, prior to setting up a pole that would be used to translate across the ARS to the asteroid.
They would then peel back part of the bagging surrounding the rock, allowing for hands on access. Photo documentation would take place, along with the use of tools to chip away at the rock, allowing for sample collections.
A number of these procedures have already been tested during NEEMO missions.
Following their visit with the asteroid, the Orion would depart from the ARS and head back to Earth for a nominal re-entry into the Pacific Ocean.
The Follow On Missions:
The new mission is set to become a pathfinder for future missions to larger asteroids in deep space.
However, that in itself will require another leap forward in mission capabilities, with evaluations into sending what would be a considerable amount of hardware to a NEA destination still under evaluation.
These evaluations range from multi-launch SLS campaigns as the baseline approach, to the use of an Exploration Platform or Gateway – as the centrepiece of several exploration pathways – for the alternative option.
A several month internal study – a high level effort within the ongoing NASA exploration roadmap evaluation drive and specific to the Gateway – was conducted and subsequently stalled at the political level.
The study related to a Gateway that would be built at the International Space Station (ISS) and then sent to Earth Moon Lagrange point (EML2) via Solar Electric Propulsion (SEP). This Gateway would provide a staging post for missions to the Lunar Surface, NEAs, Mars and potentially other destinations.
For a NEA specific mission, Boeing outlined a conceptual approach involving the EML2 Gateway at last year’s Global Exploration Workshop. Under this Boeing plan, Solar Electric Propulsion would be used by NASA for NEA missions – a technology also cited by Aerojet.
This new propulsion system would be gradually developed over the next 10 years, although a demonstration flight would be capable of readiness by 2014.
A NASA docking system, Spacecraft boom, triple panel SEP module, Solar Array mast, and Alpha-joint (similar to the ISS’ Beta joint) would be developed between 2016 and 2020 – all leading to the creation of a 320 kW SEP operational spacecraft for NEA missions by 2022.
Using the new SEP technology, transit from the EML2 point to the NEA of interest would take approximately 100 days with SLS’ third stage used to “kick start” the stage and shorten the trip. SLS would be involved with the Gateway plan.
Investigations at the NEA would last for approximately 30 days before a ~235-day trip back to Earth for a total mission duration of roughly one year.
This alternative plan is internally considered as the most exciting option within NASA circles for missions later in the 2020s, after the newly announced mission.
(Images: L2 Content, NASA, NEEMO and Boeing)
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