David Kipping
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davidkipping.bsky.social
David Kipping
@davidkipping.bsky.social
Astronomy, Exoplanets, Astrobiology, Cool Worlds Lab, Columbia University. Be kind to one another.
“Carl… Carl…”
October 11, 2025 at 6:15 AM
3I/ATLAS, a quick update.

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October 6, 2025 at 5:35 PM
The magnetic field produces in this configuration could actually be useful in its own right, such as providing protection to a Mars base for example. And given these things weigh just ~kg, made of existing materials and powered solely by the Sun, we could make a lot of them.
July 26, 2025 at 4:17 PM
We speculated that even faster speeds could be obtained by electrically charging the tips, providing a restoring force. This creates a rotating dipole that radiates and the new terminal speed is set by energy balance, and is ~1000 km/s (0.3% c!) - again just using the Sun!
July 26, 2025 at 4:17 PM
A chipsat, similar to that proposed by Breakthrough Starshot, is released just before breakup, flying off in a tangential trajectory out of the Solar System. In principle we could boost the speeds by using eccentric orbits + Oberth effect, graphene sheets and gravity assists.
July 26, 2025 at 4:17 PM
After ~3 years @ 1AU, TARS would spin up to 12.1 km/s which is the critical velocity when the centrifugal force exceeds the tensile strength of the CNT sheets. Adding on the quasite orbital velocity, the ends are moving at 40.4 km/s - exceeding the Sun's escape velocity.
July 26, 2025 at 4:17 PM
The whole thing is scalable but our paper considers the example of a 63m x 7m x 2.6um design weighing 1.6 kg made of CNT sheets. The strange dimensions are required for stability against tumbling (T-handle effect). One could imagine TARS being folded up at launch then unfurling.
July 26, 2025 at 4:17 PM
However, there's also an outward force trying to push TARS away from the Sun, which is bad since radiation pressure drops off as distance^2. So, we combat this by placing TARS in a "quasite" orbit, an idea I came up with in a previous paper: doi.org/10.3847/2515...
July 26, 2025 at 4:17 PM
The simplest way to understand TARS is to think about something like this, two thin paddles joined by a tether. One side is painted silver & the other dark, with opposite phases. The silver side feels 2x the radiation pressure as the dark side, and thus TARS feels a torque.
July 26, 2025 at 4:17 PM
New paper! Allow me to introduce TARS = Torqued Accelerator using Radiation from the Sun. TARS (yes inspired by Interstellar!) is a rotating light sail that's capable of launching chip sats into interstellar space using only radiation from the Sun, so let's dive into how it works.
July 26, 2025 at 4:17 PM