"If you have a coin and flip it just once, what does that tell you about the odds of heads versus tails?" asks Heather Knutson, assistant professor of planetary science at Caltech. "It tells you almost nothing. It's the same with planetary systems," she says.
For as long as astronomers have been looking to the skies, we have had just one planetary system—our own—to study in depth. That means we have only gotten to know a handful of possible outcomes of the planet formation process, and we [...]
Astronomers using the National Science Foundation’s Green Bank Telescope (GBT) in West Virginia, along with data from other large radio telescopes, have discovered that our nearest galactic neighbors, the dwarf spheroidal galaxies, are devoid of star-forming gas, and that our Milky Way Galaxy is to blame.
These new radio observations, which are the highest sensitivity of their kind ever undertaken, reveal that within a well-defined boundary around our Galaxy, dwarf galaxies are completely [...]
Two NASA astronauts wrapped up a 6-hour, 34-minute spacewalk at 2:50 p.m. EDT Wednesday to replace a failed power regulator. Flight Engineers Reid Wiseman and Barry Wilmore also relocated equipment on the station’s exterior to begin setting the stage for a reconfiguration of the orbiting complex to accommodate future commercial crew vehicles.
Wiseman, the lead spacewalker for Wednesday’s excursion, and Wilmore switched their suits to battery power at 8:16 a.m. EDT, signaling the start of [...]
Peering out to the dim, outer reaches of our solar system, NASA’s Hubble Space Telescope has uncovered three Kuiper Belt objects (KBOs) the agency’s New Horizons spacecraft could potentially visit after it flies by Pluto in July 2015.
The KBOs were detected through a dedicated Hubble observing program by a New Horizons search team that was awarded telescope time for this purpose.
“This has been a very challenging search and it’s great that in the end Hubble could accomplish a de [...]
What makes one rose bush blossom with flowers, while another remains barren? Astronomers ask a similar question of galaxies, wondering how some flourish with star formation and others barely bloom.
A new study published in the Oct. 16 issue of the journal Nature addresses this question by making some of the most accurate measurements yet of the meager rates at which small, sluggish galaxies create stars. The report uses data from the European Space Agency's Herschel mission, in which NASA is [...]
First “ice giant” planet found in another solar system.
COLUMBUS, Ohio—Our view of other solar systems just got a little more familiar, with the discovery of a planet 25,000 light-years away that resembles our own Uranus.
Astronomers have discovered hundreds of planets around the Milky Way, including rocky planets similar to Earth and gas planets similar to Jupiter. But there is a third type of planet in our solar system—part gas, part ice—and this is the first time anyone has sp [...]
APEX reveals hidden star formation in protocluster.
Astronomers have used the APEX telescope to probe a huge galaxy cluster that is forming in the early Universe and revealed that much of the star formation taking place is not only hidden by dust, but also occurring in unexpected places. This is the first time that a full census of the star formation in such an object has been possible.
Carlos De Breuck (APEX project scientist at ESO, and a co-author of the new study) emphasises: “This [...]
In the spirit of my previous post promoting healthy, competitive industries, I wanted to toss out an idea I’ve had for several years about an alternative to inflatable structures for providing large volume pressurized space facilities. The idea is a derivative of one of the concepts I discussed for dual fluid depots in my paper I did with ULA back in 2009–to make the pressure vessel be integral with the payload fairing walls.
Normally payloads fit inside the fairings, and have to have a sufficiently large gap between them and the fairing that they don’t accidentally vibrate into the fairing during launch. This “dynamic envelope” often cuts the diameter of objects inside a notionally 5m diameter fairing to ~4.5m or less. Building your structure so its cylindrical section is the fairing structure can increase the effective cross-section of your module significantly (~35% more cross sectional area for a 5.1m vs. the 4.39m cross section used for ISS).
Here’s an illustration lifted from that paper I referenced earlier:
Integral Payload Fairing Depot Concept provides ~200m^3 of tank volume fitting within existing Atlas V payload fairings
As you can see, by building a tank that effectively replaces part of the fairing wall, you can fit over 200m^3 of pressurized volume into an existing Atlas fairing (actually closer to 250m^3 once you include that gas buffer tank shown in light blue between the big tank and the Centaur, and add in a docking node fitting into the nosecone area). I haven’t run the numbers on versions flying on Delta-IV or Falcon 9, but figure they’re likely similar since all have ~5m diameter fairings.
In many ways this concept is pretty similar to what was done for Skylab. While NASA originally intended to use a “wet workshop” design for Skylab–where the habitable space would actually be filled with propellant during launch and only converted to warm living space after reaching orbit–in the end they ended up going with a dry-lab that was pre-fitted-out with internal structures, wiring, and a lot of the hardware that would be used on-orbit.
For an Atlas V-launched version, the 5.4m OD of the fairing would work well with the 5.1m OD LH2 tank tooling used for the DCSS upper stage, leaving about 15cm on each side for a variant of Quest Thermal’s MMOD-MLI that could include a thin aeroshell over the outside similar to the LV-MLI. With a tank stretched to fill the available length in the long Atlas V fairing, you’d have somewhere in the 210-220m^3 in the main cylinder, with a pressure vessel and MMOD/MLI dry mass under 4 tonnes.
Quest Thermal MMOD-MLI Test Article
Is this revolutionary? Not really. But I think it’s a reasonable competitor to inflatable modules for a similar job. Some of the benefits of this approach, compared to inflatables:
Much simpler, lower-risk design, analysis, and fabrication. You’re basically just doing a stretched propellant tank for your pressure vessel. Most of the complexity in a useful hab isn’t in the pressure vessel itself, so making that as simple as possible might not be a bad idea.
Similar overall volumes. The BA330 would only be about 30-50% bigger (220-250m^3 vs 330m^3 for Bigelow), in spite of the benefits of inflation. This would also be significantly (~50%) bigger than the largest ISS module–Kibo.
More efficient internal volume utilization. Unlike an inflatable you wouldn’t have a rigid core structure taking up prime real estate down the center of the module, and you also wouldn’t need to have all the volume associated with the inflation pressurization system, as you could launch the module pre-pressurized. If you wanted to have a wide open space for some reason, this would provide it a lot easier than you could get with a comparable inflatable structure.
If you went with an isogrid aluminum construction like the DCSS tank, you can probably put threaded/helicoiled holes at the repeating nodes where the 6 rib elements come together. This would make it very easy to attach structures or other systems in a reconfigurable manner, whereever you want. With some work, you might even be able to have some set of the node holes done as blind (not thru) tapped holes on the outside for externally mounting hardware.
Since the structure is rigid, it’s possible to mount items like solar arrays or radiators to the outside of the structure a lot easier than it is with a soft-walled structure. These pieces would have to be stowed somewhere else for launch (maybe back in the gap between the centaur stage and the bottom part of the fairing), and then moved into place using a robot arm, and attached to some form of separable interface. There are some definite details that would need to be sorted out there, but nothing that seems to hard. Plus you wanted a robot arm anyway for delivery vehicle capture/berthing. This may not seem like that big of a deal, but one of the real challenges with a Bigelow module is all of those external pieces have to attach to two fairly narrow pieces of real estate at either end. Being able to attach to the cylinder section gives you a lot less crowded of a space to deal with.
Adding windows or other local stress points is also a lot easier to do with a rigid structure, as is adding vacuum electrical or fluid pass thrus along the cylinder section if desired.
Now, I didn’t mean this post as bashing on Bigelow or inflatable structures. I’m a big fan of what Bigelow is trying to do, and have nothing but respect for a guy willing to put that much of his own money on the line to make a dream happen. That’s balsy. I’m not even necessarily saying that my approach actually is better overall once all factors are taken into consideration. I’m just saying it’s another approach to solving the “large amounts of pressurized volume” problem that’s not particularly high-tech or high barrier-to-entry.
While I definitely want to see Bigelow successful, I’d also love to see him have some successful competition as well, and I just wanted to point out there are other legitimate approaches for solving this problem that I hope someone will try out.