(Note: During the 2013 Space Elevator Conference, several workshops were held, delving more deeply, with audience participation, into specific Space Elevator related topics. This is a summary of one workshop, Space Elevator Space Operations.)
Champions: Skip Penny and Pete Swan
Initial Presentation: “Tether Climber Operational Phases” – Skip Penny
Goal: To stimulate thoughts and involve the conference attendees on timely topic
Outputs: Summary Report to be posted on ISEC website in 60 days
- 30 minute talk on topic, based on paper: status of topic, past history, future approach, technological challenges [as well as legal and other] etc.
- 5 minutes of discussion on handout sheet [stimulation of ideas and areas to discuss]
- 10 minutes of brainstorming on topics to discuss
- 45 minutes of brainstorming in small groups [broken up along the lines of the selected topics]
- 20 minutes of discussions by small groups to large audience on results of brainstorming
- 10 minute summary
- Champion and helper summarize the results and put on web
Issues: The design of space elevator climbers will require a solid space operations concept developed prior to “kick-off.” As such, the identification of the various processes associated with the ground and space operations will require inputs from diverse sources and experiences. This mini-workshop will consolidate inputs and summarize the concepts and proposals for operations during the lifetime of a climber.
Topic: Repair of Tethers
Major Points: Several points were emphasized:
- Sever is a real problem and requires much future study, especially with the emphasis on recovery from a sever in the lower reaches.
- A partially torn tether will need to be identified by both manual and automated methods. This could be accomplished though IR sensors on each tether climber, or searching the tether by remote means.
- The safety approaches for damaged tethers will vary depending altitude.
- One concept would be a “sliding 3-D printer” that would move the damaged location and then replace, overlay, or fuse the material needed.
- Once the damage is identified, the movement of tether climbers over that spot could be limited drastically.
No answers were expected as this is a serious topic to pursue as the knowledge of the design firms up.
Topic: Down Climbers
- The consensus is that there should be dedicated down elevators in addition to the principle mission of vertical lift for profit.
- The return climbers should only come down when they have payloads to carry [multiple folded climbers might be one payload]. The cost to come down [opportunity lost on up carrying climbers is the issue]
- The descent of climbers will probably be slower than the ascent as the danger of it getting out of control is high. The earth’s gravity is pulling the climber and significant braking capability and massive heat dissipation. The concept would be to have a motor using the downward pull to create electricity which could be transmitted to other climbers.
- The parachute is a questionable option. It will only work in the atmosphere and the tether/parachute coiling might be an issue.
Topic: Operations with a Strato-station or a High Stage One
- Many of the concepts of operations at a high stage one are parallel with the operation of a stratospheric balloon [dirigible] operation.
- The height would probably be at approximately 30 km [maybe higher] and the load would be dependent on the capability of the large balloons to stay at altitude.
- One effect that will be difficult is the day/night buoyancy issues due to heating of the atmosphere and more vertical thrust when daytime.
- Solar power for energy seems natural when you are above most of the opaque atmosphere.
- Indeed, the center of mass and flying capabilities will be important during the long periods of operations.
- Maintenance issues are real and will probably drive one to two strato-stations to ensure 24/7/365 coverage.
- There could be telescopes on the strato-station for science as well as to look for space debris and help in identifying potential tether threats.
- With the flyability of the stratospheric balloons, the tether can definitely be moved for dynamic motion to avoid space debris.
- High Stage One seems to have a good handle on these issues and looks like a very good stationary platform to work automated machinery to operate the Earth’s terminus for tether climbers and other activities.
Topic: Diagnostic Discussions
Team: Larry Bartoszek, Sandee Schaeffer, “Sam” Dalong, Vern McGeorge, Jose Fuentes
Major Points: Types of diagnostics needed for a tether climber:
- During the braking, the heat sensors must look for overheating problems, not only at the source, but as it moves. This could be bearings, wheel surfaces, ribbon surface, battery/capacitive packages, motors, and especially brakes.
- Cameras should be in many locations as monitors of the action motion and activities.
- The ability to center on the ribbon will be crucial. Many types of sensors could achieve the desired result during high speed climbs, but optical will be principle. Some of those would be on Non Destructive Inspection methods such as X-ray, gamma ray, light density measurements, and, of course, counting cross bars or other height locator items.
- There could be radar required on-board.
- There should be sensors for impacts from space objects and to detect dynamic motion that is unexplained or actual holes in tether.
- Radiation sensors are probably required as the issue is real and changeable.
- Electrical sensors for current, voltage, capacitance, and stray EMF’s. The sensors should be measuring levels and looking for anomalies such as spacecraft charging.
- There should be strain gauges on the high stress items such as the wheels and pressure structure.
- GPS can be very valuable for location, speed, and acceleration.
- The payload needs environmental sensors to monitor the environment. When the payload is people, these requirements become serious.
- It seems that streaming video is a common request – thus probably a customer need.