Category Archives: Space Tethers

Manned Circumnavigation of the Inner Solar System

Posted on April 27, 2026 by Kirk Sorensen

In 1969, a Bellcomm engineer named A. A. VanderVeen published a paper describing a family of trajectories so elegant they seem almost accidental. Fifty-five years later, the most attractive instance of that trajectory family departs Earth in August 2034. This … Continue reading →

Posted in Bigelow Aerospace, Commercial Space, Mars, Orbital Dynamics, Space Exploration, Space Tethers, Variable Gravity | 7 Comments

Lunar Space Elevator Design

Posted on April 23, 2026 by Kirk Sorensen

The previous posts in this series described what the lunar space elevator can do. This one works through the structural mechanics that determine how much ribbon material you actually need to build it. The central engineering question for any space … Continue reading →

Posted in Lunar Commerce, Lunar Exploration and Development, Space Development, Space Tethers, Space Transportation | 3 Comments

EML2 Lunar Elevator Introduction

Posted on April 17, 2026 by Kirk Sorensen

The first two posts in this series made the case for staging lunar missions at EML2 and for building a permanent station there. This one describes where that architecture ultimately leads — and it’s more extraordinary than most people have … Continue reading →

Posted in Space Tethers | 2 Comments

GEO Orbital Debris Mitigation Paper Excerpts

Posted on April 7, 2022 by Kirk Sorensen

Back in 2006, I helped a high-school student (Daniel Rodrigues) who was interested in momentum-exchange tethers to write a paper for a high-school class about a concept for a tether that would remove spent geosynchronous satellites from their orbits quickly, … Continue reading →

Posted in Orbital Debris Remediation/Mitigation, Orbital Dynamics, Space Tethers | 1 Comment

Random Thoughts: µ-xGRF

Posted on May 28, 2015 by Jonathan Goff

I’ve previously blogged a few times about Kirk Sorensen’s xGRF (variable Gravity Research Facility) concept as a way to answer the critical questions of how humans respond to hypogravity. Kirk’s concept involved a lab spacecraft and counterweight connected by a … Continue reading →

Posted in Random Thoughts, Space Tethers, Variable Gravity | 7 Comments

Random Thought: Dragon V2 as an xGRF Platform?

Posted on January 2, 2015 by Jonathan Goff

Review: How Much Gravity Do We Need, and Why Do We Care? One of my hobby horses that I’ve blogged about a few times is the question of how much gravity do humans need to be healthy? As I’ve pointed … Continue reading →

Posted in Commercial Crew, Commercial Space, NASA, Space Development, Space Settlement, Space Tethers, SpaceX, Variable Gravity | 35 Comments

Someone is Wrong on the Internet!

Posted on August 14, 2012 by Jonathan Goff

And ironically, it’s XKCD What-if that is wrong. Well, not wrong by commission, but wrong by omission. First off, I’m a huge fan of both XKCD (well the 98% of their comic strips that are SFJ) and XKCD-What If. If … Continue reading →

Posted in Humor, Propellant Depots, Space Tethers, Space Transportation | 5 Comments

Steve Canfield and his marvellous mechanical joint

Posted on June 19, 2010 by Kirk Sorensen

In previous posts I’ve mentioned that when I first got to NASA I worked in the Propulsion Research Center, which was a fun place to work because you got to think about and try just about anything you wanted to … Continue reading →

Posted in Space Tethers | 17 Comments

The Meaning of “Characteristic Velocity” for Tethers

Posted on February 24, 2010 by Kirk Sorensen

On my earlier post where I first showed the Moravec mass ratio, I introduced the concept of the “characteristic velocity” of a material, without making any attempt to explain what, if anything, this might mean. When I first read about … Continue reading →

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Recursive Algorithm for Moravec’s Mass Ratio

Posted on February 18, 2010 by Kirk Sorensen

Computing the mass ratio for a tapered tether (tether mass/tip mass) was first done (to the best of my knowledge) by Hans Moravec in an appendix to his unpublished 1978 paper, “Non-Synchronous Orbital Skyhooks for the Moon and Mars with … Continue reading →

Posted in Space Tethers, Space Transportation, Technology | 9 Comments