Time for a Canadarm Mini?

Ever since I misread the report about SpaceX’s Dragon capsule, it’s had me thinking about the utility of manipulator arms. When I first read the report linked to in my previous post, I thought that they were saying that SpaceX’s capsule would include an arm, and that its arm would grab the station and allow it to dock. Unfortunately, as a commenter pointed out, it looks like I was wrong. They are planning on getting close to the station using some sort of LIDAR system, then having the space station’s arm grab them and berth them at a CBM port.

I still think though that having a spacecraft with a manipulator arm on it (or at least modularly attachable as an optional feature for any given flight) would be a very useful thing to have. I did a little reading about the ISS’s “Canadarm 2”, and realized that this is way bigger than what would be needed for an on-board manipulator arm. The stat’s I’ve been able to see so far indicate that the Canadarm on the shuttle weighed in at about 450kg total, and the Canadarm 2 tops the scales at a hefty 1800kg. The important thing to realize though, is that both of these are capable of handling really big payloads (over 100,000kg for the station’s Canadarm 2), like oh, mating the shuttle to the space station or vica-versa. A small capsule drying to mate itself to a station or trying to move a satellite is likely only going to need something a fraction as heavy. Say something in the 50-150kg range. Since this would be mated on the ground to the vehicle preflight, and could be brought back for maintenance on the ground between flights, it wouldn’t need a lot of the bells and whistles that were added to the Canadarm 2.

Since there are many companies out there developing CEV’s, capsules, or other sorts of manned or unmanned spacecraft, there could be some serious potential business if MDA Space Missions were to develop a generic manipulator arm. Right now they’ve been building expensive one-offs for the shuttle and the station, but imagine if they could sell a dozen or so of these smaller, simpler, generic systems? I don’t know if they could really make the busines case close at a reasonable price, but if they could, here’s my guess at what some ideal stats would be:

  • Total Arm Mass: 100-150kg
  • Maximum Handling Capacity: 15000kg
  • Maximum speed: ~12cm/s unloaded, ~2-3cm/s fully loaded
  • Power Consumption: Less than 250W
  • Length: 8-12m extended
  • Stowed Envelope: Less than 2m x .5m x .5m

Those are just a guess. Don’t actually know if that’s feasible or not, or if any of those suggested requirements are mutually exclusive.

The applications of such a system would be numerous:

  • Recovery of damaged satellites
  • On-orbit check-out and deployment of satellites
  • Simpler “docking” with space stations and propellant depots
  • On-orbit assembly of satellites, transfer stages, stations, etc
  • Simplified rendezvous and docking proceedures

The list could go on much longer.

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Jonathan Goff

Jonathan Goff

President/CEO at Altius Space Machines
Jonathan Goff is a space technologist, inventor, and serial space entrepreneur who created the Selenian Boondocks blog. Jon was a co-founder of Masten Space Systems, and is the founder and CEO of Altius Space Machines, a space robotics startup in Broomfield, CO. His family includes his wife, Tiffany, and five boys: Jarom (deceased), Jonathan, James, Peter, and Andrew. Jon has a BS in Manufacturing Engineering (1999) and an MS in Mechanical Engineering (2007) from Brigham Young University, and served an LDS proselytizing mission in Olongapo, Philippines from 2000-2002.
Jonathan Goff

About Jonathan Goff

Jonathan Goff is a space technologist, inventor, and serial space entrepreneur who created the Selenian Boondocks blog. Jon was a co-founder of Masten Space Systems, and is the founder and CEO of Altius Space Machines, a space robotics startup in Broomfield, CO. His family includes his wife, Tiffany, and five boys: Jarom (deceased), Jonathan, James, Peter, and Andrew. Jon has a BS in Manufacturing Engineering (1999) and an MS in Mechanical Engineering (2007) from Brigham Young University, and served an LDS proselytizing mission in Olongapo, Philippines from 2000-2002.
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8 Responses to Time for a Canadarm Mini?

  1. Neil H. says:

    It seems that having the arm affixed to the capsule on the ground could complicate reentry. Although this adds to the arm’s weight, it seems ideal to have the arm reattachable/mobile, and just have a hard-point somewhere on the capsule’s surface that the arm (or maybe even some other modular “accessory”, or an attachment point to other craft) can attach to.

    One could even have the modular arms kept in orbit, either on a station or an autonomous tug. That way the weight of the arm would only have to be lifted once.

    On a more comical note, there’s some precedent for having multiple arms on the silly-looking grappler ships from the anime series Outlaw Star.

  2. Jon Goff says:

    Neil, I’m assuming that robotic arms would be located either internal to the vehicle (behind nosecone hatches like on Dragon, or located in the “lee” side of the vehicle like some of the hardware on the CXV. It wouldn’t work for everyone, but I think that’d be by far the cheapest way to do things. Once you try to make the arm mobile, it gets a lot more complicated fast. Now, I wouldn’t mind seeing an arm whose connection interfaces were such that it could be detached and rebolted down somewhere else by say a spacesuited person, but I think KISS is what is called for here.

    ~Jon

    PS Thanks for the link on the XPPS article.

  3. Big D says:

    RMS is pretty much a must-have for any really advanced space program. Try building a skyscraper without a crane. There’s some money to be made in developing lightweight, sensor-laden arms that provide excellent visual/tactile/force response to the user. It doesn’t matter what you’re doing, if it involves mucking about in space, an arm beats the tar out of EVA for anything that it can reach that doesn’t absolutely require a human touch–and even then, it can greatly assist them, as has already been proven on Hubble.

  4. Matt Wronkiewicz says:

    One of the problems with the ISS arm is the limited visibility. At least once they’ve bumped it into the outside of the station, causing unknown damage. This problem would be even worse on Dragon. The capsule doesn’t have very large windows, and it doesn’t have the advantage of multiple perspective views like ISS does. You might be able to improve the situation with computer modeling, more windows, external cameras, and really good tactile feedback.

  5. Big D says:

    That’s doable–lipstick cameras are light and cheap, and force sensors should be in place not just to give feedback on the tip, but to warn if any parts of the arm are receiving force they shouldn’t be.

    The rest is just sensor fusion and ergonomics.

  6. Ken says:

    It seems silly that an arm wouldn’t have safety stops in it (the control software) to protect damaging whatever ship it’s attached to (like cnc equipment often has.) You don’t need camera’s for this, you just need to know the geometry of what you’re working with.

    Hardpoints sound like a great idea. The first arm could even be used to add others. I also think that bringing them back once you have them in space doesn’t make sense either.

    I can see it now, ‘Jed’s orbital arm rental’ open for business. He’ll even bring it to your orbit, just don’t mind the barking dog, he’s really friendly and doesn’t bite.

  7. tstetler says:

    Ever see the snake-like robots? Mount your cams/sensors and coil one up under a panel.

  8. Anonymous says:

    MDA’s OE – Satellite Servicing Arm

    http://sm.mdacorporation.com/what_we_do/oe_9.html

    J9

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