Solar sails to help keep pole-sitting satellites in their place

Pole sitting was a fad in the United States in the 1920s, but ESA is putting a modern orbital spin on the practice. Investigating advanced orbital mechanics, the space agency has concluded that it’s possible to build a hybrid solar-sail/electric-propulsion satellite that could hover over either of the Earth’s poles by balancing the pull of the Earth and the Sun.

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CrazyNeutrino said:

Solar sails to help keep pole-sitting satellites in their place

… consisting of a solar sail and an electric propulsion engine like a Hall thruster. The solar sail would catch the solar winds to provide thrust, which would be augmented by the gimbal-mounted thruster powered by tiny solar cells embedded in the sail. Separately, the solar sail and thruster wouldn’t able to provide the proper thrust-to-weight ratio, but together they could balance the equation of forces of the Earth and the Sun and place the spacecraft into a tiny orbit over one of the Earth’s poles with a minimum expenditure of propellants.

These spacecraft are also considered to enable displaced geostationary orbits

That’s new. I first looked into the impossibility of having a spacecraft hovering near the pole in the late 1970s. I didn’t succeed, but didn’t think of solar sail. What altitude are they talking about?

Found it, Figures 9 and 10 of http://www.esa.int/gsp/ACT/doc/ACTAFUTURA/AF04/papers/AF04.2011.81.pdf

Pole-sitter orbit at an altitude near ~0.015 AU, that’s 2,250,000 km. Compare to Moon orbit of 384,400 km, and Sun-Earth L1 & L2 Lagrangian point distances of 1,500,000 km. That’s a bit further away than I’d like, perhaps it can be reduced. The displaced geostationary orbit looks more promising.

mollwollfumble said:

That’s new. I first looked into the impossibility of having a spacecraft hovering near the pole in the late 1970s. I didn’t succeed

You failed to find it impossible?

The Rev Dodgson said:

mollwollfumble said:

That’s new. I first looked into the impossibility of having a spacecraft hovering near the pole in the late 1970s. I didn’t succeed

You failed to find it impossible?

That too. Correction:
I first looked into the possibility of having a spacecraft hovering near the pole in the late 1970s. I didn’t succeed