One of the key concepts discussed in the book “Opening the High Frontier” is the idea of a combination launch system. This is a concept that combines multiple launch technologies together in order to reduce the velocity that the rocket-powered components of the launch system need to achieve to reach orbit. One of those launch assist systems is called a non-rotating Skyhook.
This video shows how a non-rotating Skyhook works.
It starts with an Orion spacecraft on a suborbital flight path that will take it within reach of a crane located at the lower end of the Skyhook. Upon capture, the crane docks the Orion with the Lower Endpoint Station. The Midpoint Station on the Skyhook, which was positioned at the upper end of the Skyhook cable for the rendezvous, then starts moving down the cable to the Lower Endpoint Station. Once the Midpoint Station and Lower Endpoint Station come together and dock, the ion propulsion system on the Midpoint Station is activated in order to start raising the orbital altitude of the Skyhook. While this is going on, the crew and passengers of the Orion spacecraft will transfer to the Midpoint Station and the Orion spacecraft will be transferred to one of the docking ports at the upper end of the Midpoint Station. Next, the Midpoint Station undocks from the Lower Endpoint Station and starts moving up the cable to the Upper Endpoint Station. Upon arrival, the passengers, crew, and Orion spacecraft are transferred to the Upper Endpoint Station, and the Midpoint Station starts back down the cable to the lower end. Once the Midpoint Station has arrived at the lower end of the cable and the Skyhook is at the proper orbital position, the Orion spacecraft is released from the Upper Endpoint Station to a higher orbit.
The power for all these orbit changes comes from the ion propulsion system on the Skyhook. Since the ion propulsion system is much more fuel efficient than a chemical rocket motor, the amount of propellant that needs to be carried into orbit is greatly reduced. The reduced velocity required for flying to the lower end of the Skyhook also increases the payload fraction of the launch vehicle and allows for the use of a smaller reusable launch vehicle, all of which reduces the cost of getting to orbit.
The Skyhook shown in the video is called a Basic Skyhook. In the beginning, when combined with an air-launched reusable first stage launch vehicle, it has the potential of reducing the cost to orbit by 85%. Over time, as the Skyhook is made longer, the launch vehicles get better, and the flight rate increases, it has the potential of reducing the cost to orbit to $20,000 per person.
I strongly recommend watching the video full screen, with the sound turned up!
Index of Articles
- Opening the High Frontier
- Skyhook, a Journey to Orbit and Beyond
- In the Beginning . . .
- Why do Rockets Cost so Much?
- Combination Launch Systems
- It’s All About Speed!
- Visions of the Future
- The Call of an Unlimited Future
- Combination Launch Systems, part 2
- Outward Bound: Beyond Low Earth Orbit
- and someday . . . Starships!
- Mars: how to get there
- Outpost Space Stations
- Dreams of Space
- The Moon or Mars?
- Skyhooks and Space Elevators
- Stratolaunch and the X-15
- Starship Congress
- Making Spaceflight Affordable
- How a Combination Launch System Works
- Starship Conference 2017
- New Worlds Conference 2017
- Opening the High Frontier
- Building a Spacefaring Civilization
- Space Exploration and the Future
Other websites
- Skyhooks, Space Elevators and Space Exploration
- Vertical Accelerator Launch Tower
- Combination launch system
- Opening the High Frontier (the Book)
Videos
Have you thought of non rotating skyhooks anchored at Phobos and at Deimos?
To the best of my knowledge, that was first proposed by Dr. Paul Penzo of JPL back in 1984. You can read about it in the Tethers in Space Handbook on page 70. And yes, it is great idea that will eventually be part of a transportation system that will help make travel between Earth and Mars affordable to everyone. It will also be important for making travel to the asteroid belt affordable.
Penzo’s tether lengths are similar to the lengths I found when looking for a Zero Relative Velocity Transfer Orbit ZRVTO between Deimos and Phobos tethers. I wonder if Penzo used a similar process. Here’s a pic showing my math.
This method could be used to find ZRVTOs between any pair of tethers whose anchors are in coplanar circular orbits.