Sundancer Orbital Trajectory Implications (Part Two)

Sundancer Orbital Trajectory Implications (Part One)

In the first post in this series, I hinted at the idea that there may be a serendipitous benefit to Bigelow’s choice of orbital inclination for Sundancer. I had received a refined version of the groundtrack trace, and it was subtly different from the first one, so I was trying to figure out exactly why it was different–just to make sure that I wasn’t getting old data or had made some mistakes. I’ve received enough clarification to post this next section, but I’ll probably have to wait another few days to finish things up, so bear with me–hopefully it will be more than worth the wait.

So, going back to the first part of this series, the main reasons driving the selection of the 41 degree repeating ground track orbit were: launch abort safety, providing a good view, and providing daily launch opportunities from Cape Canaveral (as well as daily landing opportunities at places like Edwards or White Sands). However, when I was looking at the US groundtrack map included in the Lockheed document, I noticed that Cape Canaveral wasn’t the only existing or proposed US launch site that happens to be right under the ground track.

I don’t have a good trajectory analysis software tool on hand, so I pinged a couple of friends that do, and over the past two weeks one of them helped me do some analysis of various launch sites across the world. We took the publically available information (with refinements from the info posted on L2 of, and tried to back out from that a global groundtrack trace. The new data I have covers the groundtrack over the US, so while we try and figure out how to update our STK simulation to reflect the new info, I can at least comment on other US launch sites that could launch to or receive landings from Sundancer.

But with those caveats and disclaimers in place, let me dive into what we found.

Sundancer US Groundtrack
So here’s the most up-to-date map of the US with the groundtrack for Sundancer superimposed:

As you can see, in addition to Cape Canaveral, several US launch and landing sites get at least daily launch and/or landing opportunities. Now, I’m not sure how far away from the groundtrack you can be and still reach it during a launch (ie I’m not sure how much extra delta-V that costs, and where the penalty gets so big that it’s no longer worth it), but there are at least a few of those sites that are directly underneath the groundtrack shown:

  • Wallops Island Launch Facility (located in Virginia) gets a launch opportunity every day on a descending track. Fortunately it looks like it is on an azimuth that Wallops can launch into. Wallops happens to have nearby communities and can only launch into a limited number of angles.
  • White Sands, NM and the planned New Mexico Spaceport both have an opportunity once per day on a descending node.
  • Nevada Test Site, NV also gets an opportunity once per day earlier on the same descending node. This was one of the proposed sites for Kistler’s K-1 to launch out of. I’m not sure about the distances, but White Sands or New Mexico Spaceport might be far enough down range to allow the first stage to land there instead of committing a Return to Launch Site burn–this could increase payload substantially.
  • Blue Origin’s site near Van Horn, TX is also fairly close to that same descending ground track.
  • The Chugwater, Wy facility that Frontier Astronautics is trying to get a launch site license for gets a daily launch and landing opportunity (at the peak of the orbital pass that gives Wallops its launch opportunity).
  • Mojave Spaceport and Edwards Airforce Base are close enough for landing with a low cross-range vehicle (only need about 75-150 miles of cross range depending on which groundtrack pass you land off of), but I’m not certain if the delta-V penalty for a dogleg maneuver would preclude launching from there on the ascending pass that goes a bit to the south. If so, it might at some future point allow for a three-orbit mission that does a first orbit rendezvous, spends one orbit transfering crew and cargo, and then returns to its launch site the same day it leaves.

There are probably a few sites that I left out, but I thought that this would be interesting.

Void Where Prohibited, Your Mileage WILL Vary
Now, whether a given launch site can be used for this mission is going to depend a lot on subtle details of the planned trajectory, vehicle characteristics, operating modes, etc. An RLV can overfly inhabited portions of the country on its way to orbit so long as the “E-sub-c” number (the statistically predicted number of “Expected Casualties) per launch is low enough. This ends up being a combination of how densely populated the area under your groundtrack is, how fast your Instantaneous Impact Point is travelling when it passes over, and the probability of failure at that given point.

Obviously tweaking your trajectory to either avoid major population centers, or at least to have your IIP cross over them very quickly is preferred. For a vehicle like Sea Launch, even though they’re using the unfortunately rather unreliable Zenit vehicle, they were able to get a launch license very easily for the specific reason that there’s almost nothing for them to hit out there in the middle of the Pacific (well, alas, I may have to rephrase that as “nobody else” for them to hit…) It also helps if you’re not intentionally dropping hardware every flight.

IIP is a calculation of where your vehicle would crash if its engines shut off and it went ballistic from that exact point in time. The interesting thing is that your IIP ends up travelling a lot faster than your vehicle itself, and in fact makes a complete loop around the earth on the way to orbit. There are subtle tricks that you can (and probably will have to) do in order to make sure that your IIP doesn’t spend too much time crossing over a given population center.

Lastly, the odds of failure depend on both the proven reliability of the vehicle, and the riskiness of any given operation. At first, for a vehicle with no track record, the assumption is (for Ec calculations) is that you will crash your vehicle every single flight. However you’re more likely to crash during certain risky maneuvers (such as staging, major throttle-ups/downs, Max-Q, etc). So you end up doing something that involves taking the total launch IIP trace for your vehicle, dividing it up into units of equal time, calculating the odds of it failing during each time window, adding dispersions, and figuring out what’s the worst that can happen if it fails at that point. Or something like that. I can’t say I know personally, as I’ve never had to experience that particular form of masochism.

Bottom line, if you want to launch from anywhere, you’re going to be spending a lot of time with the AST. Make friends with them. Learn your stuff. They’ll be right sometimes when you’re wrong, and they’ll be wrong some time when you’re right. Humility mixed with boldness in correct ratios is in order. My gut feeling is that each of these launch sites, with the right amount of hard trajectory shaping, can be made to work. I’m sure that any AST guy/gal reading this is probably getting an ulcer by now, but I’m pretty sure they’d agree that there’s probably a way to do it. Just budget a lot of time, and hire an ex-Marine if you can…

Further Thoughts on the Ramifications
Anyhow, assuming that some or most of these sites are feasible, I can think of a couple of near and medium-term ramifications:

  • If SpaceX can get Falcon I flying reliably, and get Falcon IX built, they might be better off launching out of Wallops than Cape Canaveral. At Wallops they’d be one of the major players instead of being the poor stepchild. At Wallops they wouldn’t be anywhere near as remote from civilization (and replacement parts or LOX shipments) as they are at Kwajelein. They could still launch into Sundancer‘s orbit, as well possibly as some polar orbits. This might eliminate entirely the need to launch from Vandenburg or Canaveral, and could end up saving them a lot of time, money, and hassle.
  • As mentioned previously, if Rocketplane/Kistler ever get something flying, they also might be able to service Bigelow’s station. They only get one daily pass, so they’d have a full day to rendezvous, dock, transfer crew/passengers/cargo/propellants, and then prepare for reentry. And as mentioned earlier, they could probably bump up their orbital payload by 20-50% or more by using a downrange landing site for their first stage, like White Sands, New Mexico Spaceport, or possibly Bezo’s site.
  • This trajectory while meeting near-term needs for Bigelow and Lockheed, also ends up being long-term beneficial to both them and new players. Bigelow wants cheaper launches. Lockheed and/or Boeing would love to operate orbital propellant depots and or tugs fueled by cheap RLVs. They aren’t stupid. They’re positioning themselves so that if a new low-cost provider comes into the field that they can find a way to profit from that too.
  • Once Sundancer and eventually Nautilus are in orbit, and once they’re being regularly serviced by capsule/ELV systems like Dragon/Falcon IX or Atlas V, it will provide a proven market at a destination that is conveniently reachable by emerging space startups from launch sites that have lower overhead and less bureaucracy (like several of the new commercial spaceports that are being proposed). This can possibly help start to break out of the chicken-and-egg problem we’ve been in for so long.

Anyhow, I think this is very exciting, and bodes well for the future. There’s still a lot of ifs involved, and this may end up going the same way as so much else in commercial space has over the past several years, but there’s a lot of reasons for hope. Bigelow’s now starting to establish a track record, has substantial money, and has picked a reasonable first commercial goal. Lockheed is a well-respected, well-financed, and talented (albeit kinda expensive) company, that helps bring additional credibility to the deal. There are still unknowns involved, but I think there’s a good chance I’ll be staying up late to watch Sundancer overflights sometime in the next few years.

[Note: In the next post, once I’ve got a global groundtrack figured out, I’ll comment on foreign/non-CONUS launch/landing sites that can access Sundancer. It may be a while, but preliminary info shows that at least Woomera and Kwaj look like they might be close. And the old unrefined data also showed the Japanese, Chinese, and Indians potentially winning as well. What will STK hold in store? Stay tuned…]

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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.
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18 Responses to Sundancer Orbital Trajectory Implications (Part Two)

  1. ザイツェヴ says:

    So, does anyone have an idea what delta-V is necessary to shift orbital planes, per a degree of difference? The question is, does a Soyuz carry enough propellants? I think it cant haul quite a bit more than necessary for the mere deorbit burn. But then it’s quite a pudgy ship at 7t of mass.

  2. James says:

    Woomera? That would be awesome! It means i’d be able to stay in the southern hemisphere and not feel totally left out 🙂 Can’t wait to see the next part.

  3. mz says:

    How close will this be to Kourou? (in South America, about zero degrees) They’ll soon have a Soyuz pad there…

  4. Jon Goff says:

    My friend with the name in some eastern language that I don’t know,

    Plane changes are typically very costly. Basically if you take an isocoles triangle, with the two equal legs being orbital velocity, with the angle between them being the relative angle between the two planes, the third leg is the velocity change needed. Since each of the two equal legs is 7.2km, that means that the short leg is actually pretty propellant intensive. If I’m not butchering the math (I think it equals 2*v0*sin(theta/2) where v0 equals orbital velocity). That gives me about 127m/s for 1 degree change, and for the 10.6 degree change to get from 51.6 degrees to 41 degrees, it is about 1330 m/s. 1330m/s is probably a lot more than can be made up for by Soyuz. It’s already up around half the delta-V to get into a Geostationary Transfer Orbit.

    Now, if the Russians ever get that pad a Kourou built, that’s a different story.


  5. Jon Goff says:

    James, Mz,
    I’m just eyeballing things for now–the refined trajectory I got had three passes shown, and one of them did appear to pass near Woomera.

    The older data showed Woomera being missed by quite a margin, but this appears to be a lot closer. Likewise the old data showed Kourou and Alcantra both being missed by a decent margin, but that may change with the refined ground track.

    Anyhow, I don’t have much more I can say about international sites until I have the final updated groundtrack in. Maybe next week.


  6. Anonymous says:

    Jon, just one quibble, and its about semantics:

    there’s no such thing as an “ex-Marine,” (unless you count Jack Murtha.)

  7. Roger Strong - says:

    Wouldn’t the traditional satellite industry be a greater market for Sundancer and even Genesis modules?

    Consider a main problem with modern satellites: Often a communication satellite is boosted into a retirement orbit while still working fine – other than running low on fuel. Or maybe a gyro fails, making an otherwise working sat useless. They’re not built for repair, refueling or refitting.

    The big exception, the Hubble telescope, illustrates why. Even being designed for refit and repair, you need to do it with space walks. And those take years of training, practice and planning, not to mention space suits and a spacecraft with an air lock.

    But what if you built your satellite around a Sundancer or Genesis module? A simple manned COTS-style capsule like SpaceX’s Dragon could dock with it. (Or a Soyuz. Competition is good.) Technicians could go through the docking port and work in a cramped but shirt-sleeve environment. There they can replace circuit boards, gyros or fuel canisters. Science experiments could be retrieved. I read somewhere that the skin on a Genesis is radio-transparent – even the antennas could be inside.

    Imagine this idea eventually taken out to geosynchronous orbit – in other words, with several Genesis-based satellites all in the same orbit. A COTS style spacecraft could visit and refit more than one satellite per launch. Eventually you’d want to launch a base for the repair crew – a permanently-manned Sundancer or Nautilus station – into the same orbit to cut down on launches.

    This gets you a commercial manned space industry without relying on a constant supply of ultra-rich tourists.

  8. Anonymous says:

    Might be a bit too expensive to boost and then deorbit a capsule from GEO. You’re probably be better off using an ion tug to grapple and drag the satellite out to L1.

  9. Garrett Smith says:

    Jon, when you get around to global ground tracks, I would really appreciate seeing what it looks like over Europe, particularly the western Mediteranean basin, as well as over the planned spaceport in the United Arab Emirates.

  10. Jon Goff says:

    When my friend ran the STK scenario based off of the original numbers, he plotted maps over the Middle East(to check out the UAE site), but he didn’t do Western Europe. I’ll poke him on how that’s coming along. He’s got a day job alas.



  11. Dan Schmelzer says:

    Re Wallops Island, into what direction would a rocket launch and what would be the relative cost in payload capacity versus Cape Canaveral and Omelek? I have been very skeptical of the viability of Wallops Island, but would like to hear why it could make sense.

    All of this is very interesting.

  12. Jon Goff says:

    A Wallops launch into the Sundancer trajectory would launch in a southeasterly direction. I’m pretty sure it would be an allowable azimuth, but I’m not 100% positive. There might need to be a short initial dogleg, but I’m not sure. One of the guys associated with Wallops/MARS might be able to clear things up though.

    I’m not sure what the payload cost would be. I know that there’s a payload cost associated with launching into a higher inclination than your starting latitude, and that there is a payload penalty from launching from a higher latitude. What I’m not sure is how those interact…

    Alas, orbital mechanics isn’t my strongest suit.

    As for the viability of Wallops, I’ve been iffy on it in the past, but compared to the crap that SpaceX is being put through there at Omelek, and at Vandenburg, and will likely be put through at Canaveral….Wallops isn’t used for much else than NASA sounding rockets.

    And we hope to be taking a lot of that market ourselves… 🙂

    Which means that SpaceX would be one of, or the biggest customer of the facility, so they’d have a lot more say about scheduling and such.


  13. Dan Schmelzer says:

    Thanks for the info, Jon. And good luck on taking that sounding rocket business. 🙂

  14. PHILLIP GEORGE says:

    Two years you ever see Spacex launching out of Wallops?

  15. PHILLIP GEORGE says:

    With the Augustine commission pushing for PD and commerical human space flight, what effect does this have on Sundancer for Bigalow and the other commerical HSF vendors?

  16. Jonathan Goff Jonathan Goff says:

    Regarding SpaceX launching out of Wallops? Probably not. They’ve sunk enough money into Cape Canaveral and Kwaj that I doubt they’ll want to duplicate the effort elsewhere.


  17. Jonathan Goff Jonathan Goff says:

    Well the commercial human spaceflight bit would make it much easier for Bigelow to close his business case. Propellant depots? Not sure what their opinion is on that. I tried seeing if I could arrange a visit a month ago to ask them, but it didn’t end up working out. Hopefully I can touch bases with them sometime in the future.


  18. Eric Collins says:

    With Bigelow looking to use the waste water to make propellants for the RCS systems (via Orion’s propulsion module), they may want to consider getting into the business of on-orbit fuel production. Unless I am mistaken, the current implementations utilizes gaseous H2/O2, but it would not be too far fetched to consider adding some cryo-tanks for longer term storage of LH2/LO2. With the addition of a Sabtier reactor, that could become CH4/LO2. It would be interesting if they would try something like this out on the ISS, but perhaps Bigelow will be them to it.

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