Plymouth Rock: 405 Years and Counting


The Plymouth Rock mission would have taken two Orion MPCV spacecraft, one modified for extended life support, and turn them into a single spacecraft that could undertake a six-month long mission to a small Near-Earth Asteroid. Promotional image courtesy of and ©Lockheed Martin. Click for a larger view.

What it was: A 2009 proposal by Lockheed Martin to use its Orion manned space capsule as the core of a deep space mission to the Near-Earth Asteroid 2008 EA9.

Details: Until the turn of the 21st century there were three commonly assumed steps to manned space exploration: Earth orbital, then the Moon, then the planets. While the physical gap between the first and second of these is considerable, it’s nothing compared to the step that follows. The average distance to the Moon is 384,400 kilometers; Mars never approaches the Earth to less than 54.5 million kilometers and the nature of orbital mechanics means that the path taken by any reasonable spacecraft going there must be much longer. There are several reasons why there were just eight years between the first man in space and the first Moon landing while it’s been more than four decades since with no sign of a Mars mission, but that gap is one of the biggest.

Meanwhile in recent years Lockheed Martin has been building the Orion Multi-Purpose Crew Vehicle (MPCV), an Apollo-like spacecraft built around a Crew Module and a Service Module that is currently due to make its first unmanned flight in 2014. True to its name, the Orion is supposed to be adaptable enough that it can be used for all of the missions that NASA might reasonably fly in the future, and in search of more business Lockheed has been keen to suggest ones of its own.

Plymouth Rock was one of their suggestions for the Constellation Program that began in 2004. It looked to bridge the gap between the Moon and Mars by focusing on something we’ve learned about the solar system in the last few decades. In 1980 there were fewer than twenty known asteroids that approached the Earth significantly more closely than Mars (“Near-Earth Objects” or NEOs), but as of November 24, 2012 advancing astronomical technology and fear of a reprise of the impact that killed the dinosaurs had inflated that number to 9946. Why not visit one of them somewhere out past the Moon? Not only would it increase general scientific knowledge, it would let NASA test out the technology that’s going to be needed to support astronauts on a trip to Mars without having to commit to a year or more’s travel like a full-fledged Mars mission would need.

Lockheed Martin selected 2008 EA9 as the mission’s destination, with the caveat that this selection was highly dependent on the launch date and any of a couple of dozen small asteroids might serve as a substitute. The sole criterion was that the target had to have an orbit particularly similar to Earth’s, which meant that none of them was at all notable: none even had a formal name, just a serial number, and none was larger than 75 meters in diameter. 2008 EA9 itself is approximately ten meters across.

A plain Orion wasn’t going to do the job, as it was designed for two weeks of support to the Moon and back. So a modified second Orion—the Deep Space Vehicle—would also go along for the ride. It would have been put on top of an Ares V rocket, which would have lifted it and an attached injection stage (the Earth Departure Stage, or EDS) with propellant into Low Earth Orbit. A smaller Ares I would have launched the regular Orion shortly thereafter; only two astronauts would be aboard rather than the up-to-seven that the Orion could house in Earth orbit, simply because more than that would eat through the mission’s supplies in less time than it would take for the trip there and back.

The two Orions would dock nose-to-nose in orbit and the EDS would be fired to push them on their way. Once it was out of propellant the stage would jettisoned and the Plymouth Rock spacecraft—one imagines it inevitably would have been named Mayflower—would deploy four large solar panels and begin a 92-day outbound journey. This was the other reason for only having two astronauts: each would have only 9 cubic meters to live in during the trip.


A geocentric view of the Plymouth Rock mission’s trip to and from 2008 EA9 as it approaches Earth in late 2019. Promotional image courtesy of and ©Lockheed Martin. Click for a larger view.

Roughly 12 million kilometers later the ship would arrive at 2008 EA9 and take up station about 100 meters away. The asteroid’s mass would be so small that there would be no need to worry about its gravity, to the point that the astronauts could spacewalk over to it at will, depressurizing one of the Orions whenever they needed to enter or exit their craft.

Only something resembling the MMU “jetpacks” from the early days of the Space Shuttle would be needed to explore the asteroid as it’s likely that the tiny world’s rotation would produce centrifugal forces stronger than its gravity. Altogether this would produce a negative net force pushing anything that touched 2008 EA9 back off the surface again. This is actually a point in 2008 EA9’s favour as many asteroids are believed to be rubble piles held together by nothing more than their mutual gravitation, an arrangement that would be dangerous to explore. If 2008 EA9 spins like it’s believed to, though, it must be a solid object and so relatively stable.

After five days of exploration the astronauts would fire the engines on the modified Orion and begin their return home. This would take them another 95 days and, upon arrival at Earth, they would abandon all of their craft except for the conventional Orion’s crew capsule, which would take them down to Earth.

What happened to make it fail: As originally conceived Plymouth Rock would have been part of the Constellation program, and relied on the program’s Ares I and V rockets. With the cancellation of Constellation budget in October 2010, the mission could not go ahead as planned.

What was necessary for it to succeed: A mission to a NEO was considered one of the “big three” possible missions for Constellation (along with a return to the Moon, and a mission to Mars). While NASA tended to show it as one based on an Orion mated with an Altair lander—Constellation’s equivalent of an Apollo LM—Lockheed Martin was probably in the right in contending that two Orions were the way to go. Very few asteroids that approach Earth have noticeable gravity, so a lander would be an expensive way to do something that could be done with an astronaut on EVA instead.

As a result, Plymouth Rock likely would have gone ahead sometime around 2020 to 2025 if Constellation had continued. That said, it may be not entirely dead yet. Constellation has been replaced by the Space Launch System, which is different in detail from the earlier program but similar in broad strokes. The Orion itself is still going ahead as the manned spacecraft for SLS, and so it would be easy enough to launch a close facsimile of Plymouth Rock—though probably all in one shot aboard one of the Block IA SLS rockets being developed, as they have the throw weight to do so rather than taking two launches as per the original mission design.

Interestingly it appears that NASA may actually be interested in doing so. As of this writing a Moon landing has been taken off the list of first exploratory missions, with a lunar orbiter likely to be the first and rumours of a small station at the Earth-Moon L2 point to follow. NASA is studying a similar mission they call “Asteroid Next”, but as late as last week Lockheed Martin was still proposing a “Plymouth Rock” with a new date (2024-2025 or 2029) and a different target (either 1999 AO10 or 2000 SG344, depending on the mission date).

The latter target is an interesting choice as there’s some chance that 2000 SG344 isn’t an asteroid at all, but instead the upper stage of Apollo mission rocket abandoned in orbit and lost until its rediscovery a decade ago. If NASA does pick up on the modified Plymouth Rock then that’s something that will have to be determined before any launch in 2029.

A simple animation of a Plymouth Rock mission showing the joint Orion craft travelling to 2000 SG344 (one assuming that it’s a natural asteroid) can be seen here on YouTube.

9 thoughts on “Plymouth Rock: 405 Years and Counting

  1. I find it difficult to get enthusiastic about the Orion. Yeah, better tech, but still pretty cramped, no airlock, no real provision for moving about or getting exercise… it just seems like a giant nostalgic leap backwards to the glory days of NASA.

    And of course I already know what Project Orion was, and there’s probably a subconscious resentment at the name being reused.

    • I kind of like it, just because it’s going to give us the ability to get people out of low Earth orbit again. There’s no getting around the fact that an Apollo-like approach has been the only way that’s worked in the last 55 years.

      I’m looking forward to the beanstalk whenever we figure out carbon nanotubes, mind you.

      • In my ideal (and non-budget-constrained) world, the thing for going between LEO and the moon/NEOs is a scaled-back or early version of the thing for visiting other planets: a long-duration human-habitable box with modular propulsion, the ability to add more habitat modules, and plenty of internal space. It’s not the minimum-volume personnel carrier of the surface-to-orbit/orbit-to-surface system.

    • One thing the old planners found was that the Apollo CSM spacecraft had a lot of versatility to it. Similarly, the LM and the Shuttle had to strain to be versatile (though Shuttle had inherent versatility, it’s hard to imagine it operating beyond LEO). They were both specialized, like insects. the CSM, on the other hand, could be bent to many purposes, and showed up in many different kinds of mission proposals.

      Orion would be much the same, and in fact has already been proposed for space station, L point, asteroid, moon, and Mars missions. Of course, for the longer duration missions, it needs some sort of add-on module. In Plymouth Rock, that’s another Orion. For the moon under the old regime, it was Altair. CSM was the same way, though that potential was hardly developed.

      We should never have gotten rid of the CSM. But we did. That makes Orion a second chance, to my way of thinking.


    • I can answer that one, actually. Orion’s being designed to withstand the August 1972 solar flare as a typical example of the strongest flare in a solar cycle. Lockheed Martin has determined that the aft end of the spacecraft is relatively safe because the extra material there (including parachutes for re-entry). If they really need it, the plan is to reconfigure the items in the cargo of the two Orions into one location aftwards to build a temporary storm shelter. In there they’d get a dose of 400 mSv — which isn’t great, but is half to a third of what an astronaut is allowed to absorb over a career.

      Galactic cosmic radiation is apparently much less of a problem, with the Orion being able to protect them already by design, because the mission would be relatively short as compared to the trip to Mars that’s supposed to be possible with it.

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  3. The revived proposal gives me the distinct impression that with the Orion capsule Lockheed Martin has a hammer, and they’re looking for a nail, any nail, to pound. This isn’t so much a mission to explore an asteroid as it is to let Lockheed Martin sell two Orion modules instead of just one.

    If it ever happens at all, the Plymouth Rock mission is at least a dozen years away. Is a modified Orion capsule really the best possible solution for the design of a Deep Space Vehicle that anyone could come up with during that time?

    The Deep Space Vehicle won’t return to Earth, so there’s no need for it to have the Orion’s conical shape, and there’s no need for a module with a structural frame that’s been designed to withstand the stress of reentry. So why use — and heavily modify — a second Orion capsule instead of a different module that would be better suited for the job? For example, why not a relatively simple cylindrical DSV with the docking hatch at one end and a couple of inflatable hab modules on the side? The SLS will be able to lift a much greater payload mass than the Orion suite, so why not take advantage of that capability? How about adding larger solar panels, more radiation shielding, an airlock, or more consumables?

    While I’m being skeptical … Is a ten-meter rock really a suitable target for a multibillion-dollar crewed mission? A larger asteroid yes, but it’s hard to imagine the taxpaying public getting excited about a trip to a boulder, even if NASA does rename it “Plymouth Rock” instead of “1999 AO10.” Other than a few rock samples, we won’t get anything new from this mission — it would be scheduled after a lunar orbiting station, which could provide longer and cheaper experience for humans beyond LEO. A robotic sample return mission could do the same job much less expensively and without any risk to astronauts.

    Does the risk justify the reward? If something very bad happens during a crewed Plymouth Rock expedition, it could kill the American manned space program. Imagine an Apollo 13 scenario in which the two astronauts know they’re doomed but still have three months of supplies left … ugh.

  4. “As originally conceived Plymouth Rock would have been part of the Constellation program, and relied on the program’s Ares I and V rockets. With the cancellation of Constellation budget in October 2010, the mission could not go ahead as planned.”

    That’s not really correct. Considering that NASA currently is officially supposed to send humans to an asteroid, and that it is building the SLS and Orion, it will, in theory, have the means and the motive to do something like the Plymouth Rock mission.

    The dual Orion mission has not been approved, but it has been briefed to NASA and evaluated by NASA engineers. As I understand it, this approach has very limited margins. I forget the details, but there are a number of aspects about it where if something fails, the mission fails or the crew dies. NASA would prefer a more robust approach.

    I think that available living space is a primary concern that has not really been explored very much. The astronauts need room to exercise and for privacy. Put four people in a small vehicle for six months and they’ll kill each other. The problem is that we don’t know exactly what they need or how to provide it.

    If you want to overload on this stuff, search online for the presentations from the March 2011 asteroid workshop held at George Washington University. Lots of outstanding presentations there, including one on living space. There are some really thorny issues involved with a human asteroid mission and most of NASA’s internal analysis of this has not become public.

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