Sunday, October 27, 2013

Space Debris, an Interesting Number

"On-orbit, predicted conjunctions vary based on the debris density at the altitude of the vehicle. For altitudes of 350-400 km, approximately 3 maneuvers would need to be made annually." from the FAA's Draft Established Practices for Human Space Flight Occupant Safety.

This gives one an idea of the impact space debris is having right now: an average of three maneuvers per spacecraft per year to avoid collision. As space debris is expected to increase, the costs associated with dealing with space debris will undoubtedly rise. We can also expect the destruction of more operational satellites, which has happened twice so far.

The most dangerous space debris is the thousands of large pieces, mostly Russian upper stages, in polar orbits. When these have collisions, tens of thousands of pieces of debris are created. Indeed, we may be currently in a very slow motion chain reaction of collisions creating debris that in turn creates collisions which create debris ... The debris is moving at very high speeds, so even a small piece can destroy a satellite. The film 'Gravity,' while not particularly accurate technically, highlighted this quite effectively.

What to do: the single easiest and most effective act would be to get rid of the large pieces. It's been estimated that removing 10 per year would be sufficient, statistically, to start reducing the total amount of debris in LEO assuming other activities don't add much. We should get started on serious debris reduction. Otherwise, given enough time we could easily pollute Earth orbits with enough debris to end the space age.

Sunday, October 20, 2013

Launching Commercial Space Enterprises Workshop

This workshop was put on by CASIS (Center for the Advancement of Science in Space) and the Silicon Valley Space Center 18-20 October, 2013. Highlights (for me) included:

  • CASIS will fly your ISS (International Space Station) payload for free. You can also get free astronaut time. You can even have materials returned to Earth, again, for free. By law, CASIS can give away up to half of the US resources on the ISS. Although CASIS is not allowed to charge for ISS resources, in practice you'll probably pay a small amount for one reason or another. To get (almost) free access to the ISS you can either compete in periodic CASIS calls for proposals or submit an unsolicited proposal. If you don't need power on the trip up or back there are ample resources right now.
  • Through CASIS you can get ISS Hyperspectral Imager for the Coastal Ocean images for free. They aren't on the web, but you can make requests. You can also ask that the instrument look at specific locations.
  • CASIS has a small amount of money (about $3 million a year right now) to fund proposals. Not only can you fly for free, you can even get paid!
  • Made In Space will be flying a 3D printer on the ISS in the next year or so. It will be able to print objects up to the size of a cubesat (10x10x10 cm). They are interested in ideas about what to print.
  • BBC Aerospace has a 3d printer for any weldable metal using an electron beam. They say they can make very large objects. Currently they can produce 20 lb/hour and expect to double that soon.
  • Blue Origin said that they intend to fly a hydrogen/LOX orbital vehicle by 2018. If all goes as planned, this vehicle will have a reusable first stage! They also mentioned a recent study that found a market for about 500 sub-orbital seats per year, 80% filled by tourists.
  • S3 received $250 million from private investors to develop a launcher based on a half sized version of the European reusable Hermes space plane design. The first stage is an Airbus (a commercial jetliner) which carries the space plane to 40,000 ft or so. The space plane gets up to space altitudes (100km or so) and returns for an airplane-like landing. It can carry an upper stage that will get small sats into orbit. Alternately, it could carry sub-orbital tourists. However, their target market is point-to-point high speed human transportation. They are creating a presence world-wide that they hope to develop into destinations for very fast intercontinental transportation.
  • DragonLab, which is a Dragon capsule flight on a Falcon 9, costs $100 million/flight with a maximum of 2,175 kg of returnable pressurized cargo, a maximum of 3,310 kg of unpressurized cargo (which won't return) with a cap on total payload of 3,310 kg to an ISS-like orbit. You can probably get more mass to a lower inclination orbit. For ISS inclinations, that works out to about $30,000/kg.
  • Zero Gravity Solutions presented their work on the ISS showing that micro-g strongly affects gene expression. They believe they have ways of manipulating that expression to improve plant species without genetic modification, just turning on and off genes that are already there. One target is a plant that grows in the tropics and produces jet fuel. They are working on modifying gene expression of this plant so that it can grow in colder climates; for example, Texas.

  • There is quite a lot of protein crystalography work on the ISS.
  • There are a number of small companies that offer bundling of launch services. The idea is to do the paperwork and other mundane tasks associated with launching a payload to allow the customer to focus on the spaceflight itself.
  • Alan Gassan presented some software that predicts exactly what the ISS can see on the ground depending on time. This is being used by the astronauts to take photos. There is also a crowd-sourcing app to register the images to the ground (the place is known by the time stamp on the photos but not the orientation of the camera).
  • I had a couple of not-very-well-formed thoughts while there:

  • One could use Gassan's system combined with the programmable communication testing equipment already onboard to test space solar power related energy transmission. Gassan's system would tell you when power can be transferred to ground receivers.
  • There might be an educational market for cubesats with hardware to grow plants. Hardware would include LED lights, camera, nutrient and water delivery and an API to command it. Sensors for temperature, atmospheric water content and so on would be good too. Such a cubesat has been flown, but the idea here is to make it easy for students to fly different seeds. A major problem is delivering enough water over a long enough period to get more than seedlings before the water runs out.

    I attended the conference hoping to find new killer apps for space settlement, something other than tourism and space solar power. I didn't find any, but I did see a lot of small-step progress in many directions all heading toward the commercialization and industrialization of near-earth space which, in turn, is probably essential to building the first free-space settlements. See Paths to Space Settlement.