Dust detectors on Pioneers 8 and 9 reported higher concentrations of dust impact when facing the sun than when facing away. After ruling out measurement errors, it became clear that the spacecraft were detecting streams of dust on outbound hyperbolic orbits. Radiation pressure from the sun accelerates these so-called ß-meteoroids to escape velocities.
The sun emits energy in the form of photons, which impart momentum to bodies that intercept them. This effect is observed as a weak repulsive pressure. As early as the 1920s, Konstantin Tsiolkovsky and Fridrikh Tsander first realized that this pressure can be manipulated to produce useful acceleration and can thereby achieve a wholly new class of spacecraft missions. Rather than consider the “tremendous mirrors of very thin sheets” they envisioned, we consider solar pressure acting on our extremely small Sprite spacecraft. We have shown that competitive lightness numbers can be achieved by printing the spacecraft onto ultra thin silicon, essentially integrating the sail and the spacecraft.Back to top
While passing Saturn, the Voyager missions observed time-varying, radially expanding dust clouds at the B ring. These structures, dubbed “spokes”, defied the consensus that planetary rings could be explained with gravity alone. Electromagnetic effects associated with the dust charging in Saturn’s plasma environment were soon proven to be responsible for the unfamiliar behavior. Since that first discovery, electromagnetic forces have been shown to generate a dusty halo at Jupiter, capture retrograde dust into stable orbits, and even eject streams of dust at hyperbolic velocities.
We evaluate these electromagnetic effects as a means of propellantless propulsion for our spacecraft. By artificially charging a spacecraft that is orbiting a planetary magnetic field, we can achieve Lorentz-Augmented Orbits (LAO). Here, a spacecraft’s rotating magnetic field transfers energy and momentum to and from a planet via the Lorentz force. LAO offers opportunities that solar-pressure propulsion does not because it requires a magnetic field to operate. This interaction enables energy change maneuvers at outer planets, notably Jupiter with its dense magnetic field, where solar pressure is too weak to be of much benefit. We show that high charge-to-mass ratios are significantly easier to achieve and maintain at reduced-length scales.Back to top
Exogenic dust gently lands on the surface of the Earth while its larger meteorite cousins rapidly ablate in the upper atmosphere. At extremely small length scales, the surface area of the dust can efficiently radiate away the heat generated by aerodynamic friction, even at entry velocities. We seek to use similar geometries and scales to design a passive entry vehicle capable of safely gliding or fluttering down to the surface of neighboring planets.
For more information, see:
- Atchison and Peck, "Length Scaling in Spacecraft Dynamics".
- Atchison and Peck, "A Passive, Sun-Pointing, Millimeter-Scale Solar Sail".
- Atchison and Peck, "A Passive Microscale Solar Sail".
- Atchison and Peck, "A Millimeter-Scale Lorentz-Propelled Spacecraft".