A science blog with Eric Berger

Are you excited about NASA’s L-2 destination?



The Orlando Sentinel first reported this about a week ago, and it was confirmed in a report released by NASA’s human architecture team. This report represents a first stab to lay out the space agency’s plan to send humans beyond low-Earth orbit.

The plans call for NASA to build an inflatable facility at the L-2 point beyond the moon — this is one of five LaGrange points in the space around the Earth-moon system that have stable gravity. Which means that if you put an object there it won’t move much, and therefore won’t need much fuel to keep it there.


With a modest increase in its budget, NASA believes an initial construction mission could be launched in about a decade.

So why build something at the L-2 point, besides the value of saving fuel? The report states:

A long-duration habitation capability could support a Lagrange gateway at EM L1 or L2. This facility would provide a destination for exploration systems, like the Orion MPCV spacecraft; a staging point for future missions to many destinations; a crewed, non-terrestrial laboratory for NEA or Mars sample return; and a hub for accessing or servicing systems throughout cis-lunar space.

Astronauts at the L-2 Gateway could also direct rovers on the far side of the moon, allowing them to collect samples and perform other activities of interest to scientists.


Lunar scientist Paul Spudis, who favors human exploration of the moon, is skeptical about the value of such a service:

In a way, this is “make work” for the crew at L-2.  The use of astronauts to teleoperate surface robots on the far side of the Moon is possible, but offers no real advantage over their remote control from the Earth. Much is made about the “latency factor” of time delay, but the specific tasks envisioned by these missions (i.e., the retrieval of a few kilograms of rock and soil and the deployment of a long-lived scientific station) could be satisfied by teleoperation with the three-second time lag imposed by the Earth-Moon distance.  In contrast, operation from L-2 will experience a 0.4 second lag – shorter, but worth the effort?  The completely robotic New Frontiers SPA sample return mission was originally envisioned as controlled from Earth.

Some critics of NASA’s present human spaceflight activities, who have been asking for the space agency to elaborate a timeline for exploration, said there were some positives with the plan. But like Spudis, observers such as legendary spaceflight director Chris Kraft, say NASA should simply return to the surface of the moon.

The mission to L-2, while not what I would like to see is a better step than a mission to an asteroid and Mars. And it does say it involves the rest of the space faring world (ESA etc.)

I believe that if and when we get a change in administrations there will be an opportunity to come to a consensus by involving the Aerospace community: industry, academia and the Europeans, Canadians and Japan and probably Russia. All of these will recommend a return to the Moon, a lunar base and an extended stay capability. It will require a use of all of the present assets such as Atlas, Delta, Arianne and whatever the Russians will supply. And a number of other space vehicles to be used to and from the Moon along with nuclear power plants.

The “exotics” like to throw in the idea of L-1 and L-2 etc. Maybe, but that is not really a necessary feature.The future use of the SLS is the question because it is so expensive to bring about and the operating costs will limit its use. And I wouldn’t be surprised to see it canceled.

The latter point Kraft raises is an important one. None of this proposed hardware is included in NASA’s spaceflight budget, which is largely promised to the SLS — the Orion spacecraft and a rocket to launch it and larger payloads int orbit.

In other words, NASA needs more money to actually do anything with humans beyond low-Earth orbit.  It’s difficult to envision NASA getting substantially more money than it presently receives considering the financial challenges the country faces.

So the question is whether an inflatable facility at an L-2 point will motivate the public and Congress to increase NASA’s funding. Hence the original question, I posed: Are you excited about an L-2 facility?

Eric Berger

35 Responses

  1. wdsheffer says:

    How would you communicate between L2 and Earth? It looks to be situated perfectly in the shadow of the moon. Would you put a communications satellite in L4 or L5?

    • Eric Berger says:

      My understanding is that by hovering in an orbit around the L2 point the spacecraft would be able to communicate with Earth.

    • StanleyS says:

      As seen from L2, Earth is eclipsed by Luna. Whether direct communication between Earth and L2 is possible depends on whether that eclipse is total or annular. I don’t know which it is.

    • StanleyS says:

      Another possibility is that, maybe Earth is totally eclipsed by Luna as seen from L2. But physical optics diffraction as the radio signals pass Luna’s edge will cause some of the beam to curve into the communications “shadow.” This will happen going in both directions. Since radio wavelengths are much longer than visible light wavelengths, the amount of radio beam diffraction is much greater than would be the amount of visible light beam diffraction. So maybe the radio beam diffraction is enough to make direct communication possible.

      But, if I had to place a money bet on this idea one way or the other, I would bet “no.” In my comment above, I’m just speculating.

    • JohnD says:

      A satellite in either L4 or L5 is a possibility, as it a set of relay satellites orbiting the Moon, which would have the added bonus of acting as instrument platforms for more lunar exploration. But they are most likely to put it in a “halo orbit” that has L2 as the focus and extends far enough to one side that direct communications are feasible (see A Lunar L2 Navigation, Communication, and Gravity Mission for the details).

    • StanleyS says:

      “Halo orbit”: I see. It doesn’t have to be sitting right smack dab on L2. It can be offset to the side, and orbiting around L2. This way, as seen from L2, Earth and Luna are never in a straight-line view so direct communication between Earth and the station is not blocked by Luna.

  2. Leigh Bunting says:

    L2 seems a bit weird 2 go 2. Its inherently unstable and out of direct communication with Earth. Would have thought L3 or L4 is better becoz they r inherently stable and no comms probs.

  3. Patrick says:

    If they stop spending all that time and energy on pointless wars in the middle east they could actually afford to build starships and a large number of other important technology and humanity projects could be undertaken at the same time.

  4. Jean-Pierre Sarti says:

    two words: SPACE ELEVATOR

    it would solve so many problems and make things so much easier and most importantly cheaper than what we are doing now. I understand the technical challenges but isn’t that what smart people want? A truly worthy challenge.

  5. Waylon Webbon says:

    What a complete waste of effort and resources. If you are serious about putting a space station there, just drag the current International Space Station to L2. I guess that couldn’t work because the biggest stated purpose is to provide a purpose for the new NASA rocket. Just dragging the International Space Station to L2 would defeat that purpose.

    Whatever happened to mission planning? Henry Ford built a car to drive to places, not to prove that the wheels would turn.

    Mars is our destination for exploration and settlement. If the US Government keeps fooling around, other nations or even just big companies will get there long before NASA. NASA’s obsession with safety is laudable, but please recognize that if we had been so worried about the safety of pioneers settling the US Western states, those states and those pioneers probably would not be a part of the USA. We would have insisted on testing the covered wagons and horses to see if they worked well enough. The moon and Mars will follow the same agenda as the American West. Get there NOW or forget it. Become a second class nation.

  6. Aaron says:

    I had previously found such a mission to be uninspiring. However, now that it looks like NASA isn’t the only organization attempting to send humans to Mars, it makes sense to have some kind of an orbital depot that is farther along than the ISS for re-fueling, repairs, cargo swaps, etc. I’ve become more excited about this, but I would want it to be done right: bigger than ISS, a larger human population than ISS, more international than ISS. It should represent a genuine advancement from the technology of ISS. If this isn’t the case, then it doesn’t have any hopes of achieving the ‘wow’ factor necessary to secure public buy-in.

    Let me be clear, however: there remains a serious funding problem for NASA that needs to be solved. Not a budget problem, but a funding problem. We’ve moved beyond the cheap parlor tricks of shotgunning aluminum and plastic machines that look like refrigerators into LEO and to the lunar surface. NASA has achieved breath-taking discoveries and the space race has become more complex than ever before. The same old funding ratios won’t work any longer. It’s time for Congress and the executive branch of our government to provide NASA with a much larger budget now that NASA is confronting much larger ambitions. There really isn’t any good reason that our society cannot give NASA the funds needed to budget for JWST, SLS, an L2 space station, continued use of the ISS, a human flight to Mars, private space seeding, science research in space, and planetary science missions. We should be doing all of this and plunging drills and submersibles into the icy crusts of Europa, Enceladus, and Triton.

  7. James says:

    Unless it becomes a fuel depot, it is pointless as a hub for deep space exploration. It would be like driving from Houston to Los Angeles via Denver. Now, if the only gas station is in Denver, then well, each leg is shorter than going directly to L.A.- so you need less prop. Prop is mass, and in space, mass = $$$$.

  8. Someone says:

    Here’s the way to do it:

    Add capability for the ISS to serve as a fuel depot.
    Launch a lunar command module that can serve for multiple trips to the moon.
    Then, each time a moon landing is needed, launch a new base stage for the lander, along with fuel. Keep the tanks on the ISS topped up. Keep most of the hardware in space, where the expensive part has already been paid for.

    If a relay station at L2 is needed, use a comsat.

    • Keith says:

      The ISS is not in an orbit to work as a fuel depot. You would burn much more fuel trying to break orbit and change delta-v to get to the moon then just heading there in the first place.

  9. Lou says:

    Send out super probes in every directions! I wanna to find out if there’s advanced races out there before I die!

  10. John says:

    We simply cannot afford this. We are going bankrupt and this kind of unnecessary spending has to stop. They want to cut Medicare and SS but not this waste of recourses. Our thinking is all wrong and it is about to turn us into a third world nation.

    • Justin Kugler says:

      While I agree that NASA could make better use of its resources, this is a false argument. NASA gets one-half of one percent of the discretionary budget. The vast majority of federal spending is on entitlements and defense.

      Besides, history shows us that nations that stop exploring stop advancing technologically, culturally, and politically. Not only should America explore space and figure out how to bring it more fully into our economic sphere, we should be doing the same in the oceans.

    • James says:

      Agree that we are going broke, but NASA is one of the few agencies of the federal government that actually produces anything. People get caught up on the fact that because the physical endgame of NASA takes place away from the Earth while sectors like SS and Medicare take place *on* the Earth, that somehow makes NASA a bigger waste of money. Like NASA simply puts $20 bills into the propellant tank and flushes them into space. News articles are notorious for including the price tag on any space exploration-related story.

      The truth of the matter is that NASA is one of the few agencies that actually builds stuff. The money spent on the NASA budget pays private contractors for materials and personnel to construct, operate, and support spacecraft. Production drives the economy, and while it is still a sin in a free market to drive production via the public sector (e.g. tax vs. supply/demand), it is much less of a sin than programs which simply create dependents and build nothing.

      Ergo, if NASA is to be cut, there are a lot of other non-producing agencies that need to get in line first- and yes, they happen to be Earth-bound.

    • Chalkie says:

      John. Other people have said it, but it bears repeating. Please actually look at the budget before you say things like this.

  11. Justin Kugler says:

    I am not impressed by this plan. It only exists to give SLS a place to go, not a credible response to national interests in space. A true depot for reusable in-space vehicles, assembled using existing boosters, and geared towards supporting a value-oriented series of missions… that’s something I could get behind.

    • JohnD says:

      You are right, Justin. The L2 plan is more an exercise in what is possible than in what is useful.

      We’d be much better served using those resources to get us to one of hte asteroids or even going back to the Moon.

    • Justin Kugler says:

      I’d argue that it’s not even possible because it can’t be done without an increase in NASA’s budget.

  12. Hank Jones says:

    I’m excited about any mission that takes us where we’ve never been before. New technological challenges, new discoveries, new hardware, new science.

    • .dc. says:

      dude, this is not new science, it is old theory. he only thing new about it is the new ways to do fast calculcations and mathematicla techniques to solve the equations of orbit determination and fuel efficiency as part of that. Nothing more, nothing less.

  13. .dc. says:

    It makes logical sense to place a station at this point on the other side of the moon, but how are you going to serice it? I woudl be better to build a lunar base with a space station orbiting the moon-earth system such that on a regular basis it could be serviced from earth with a shuttle type of vehicle. But what do I know sabout astrydynamics….

    • PayAttention says:

      It is far safer to dock in space than to land and take off, and it takes a lot less power, too.

  14. Ken says:

    Don’t we already have a space station that’s going out of business in a few years? Clip some booster rockets to it and drive it to a new parking lot.

    • JohnD says:

      Unfortunately, it would be neither safe nor prudent to move the ISS to L2. The ISS has such a spread out design that the stresses would probably cause quite a bit of damage unless we moved it very, very slowly (e.g., by ion thrust or via interaction with the Earth’s magnetic field). Unfortunately, that exposes the station and crew to long periods of radiation exposure in the Van Allen radiation belts. As a result, the best bet if we follow this plan is to build something new at L2.

    • StanleyS says:

      In other words, trying to apply that much acceleration to the ISS would probably cause major parts to break off and be lost.

    • Justin Kugler says:

      And it’s not going out of business, either. The ISS Program is looking at how it could operate out until 2030.

  15. Priyanka says:

    not at all impressed. NASA can do better then this.

  16. Argento says:

    If you’re going to put that kind of time, money, and effort into a project like this, think about next week, not just tomorrow. I would have moved a NE asteroid to L2 so you can study mass and gravity, planet formation, iron cores, and any other material not typically found on earth. Who says the ship we send to Mars has to look like the millennium falcon? Besides think of all the gold you can mine (just don’t sell it locally, you will devalue the market) for shielding!

  17. John Strickland says:

    James is right in at least two ways: The L2 Gateway is useless without a depot and the docking and handling facilities to transfer fuel and cargo from one kind of vehicle to another. Landing robots on the moon with expendable rockets, if you are building a facility that would let you land the robots with re-usable ferry rockets, is crazy. One of the main rationales for having a way-station at L1 or L2 is to support re-usable landers. In addition, since the NASA slice of the federal budget is so tiny, people do not realize how badly the research that would support the new re-usable rocket vehicles and depots for use in space is being squeezed out of existence. Tying the so-called gateway to the SLS is merely self-serving by the SLS supporters.