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NASA Funds Research on Nuclear-powered Solar Sails to Quickly Explore Outer Planets

By Doug Messier
Parabolic Arc
March 3, 2021
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A nominal layout of a solar sail vehicle with a central payload and avionics unit, supported by a distributed APPLE power system with the number and area of units scaled to mission power need (not to scale). (Credits: E. Joseph Nemanick)

NASA Innovative Advanced Concepts (NIAC) Phase I Award
Funding: up to $125,000
Study Period: 9 months

Atomic Planar Power for Lightweight Exploration (APPLE)
E. Joseph Nemanick
The Aerospace Corporation
Santa Monica, Calif.

The Atomic Planar Power for Lightweight Exploration (APPLE) is an enabling architecture for deep solar system missions on low mass, fast transit space platforms. We explore an alternative vehicle architecture that integrates a long-lived, peak power capable, rechargeable, and modular power system with solar sail propulsion, and examine the new missions this architecture enables.

New solar sail capability enables rapid missions to the far reaches of the Solar System (e.g. Jupiter vicinity 6 months; Saturn vicinity < 1 year, Pluto ~ 4 years). While solar sail propulsion is key to fast transit, the mission is enabled by the power system.

APPLE comprises a durable radiation-hard battery that is integrated with a radioisotope electric power system to in a modular, planar form factor to power a solar sail vehicle. It is powered by a layered structure of radioisotope material backed with layers of solid-state, radiation-hard battery and thermal-to-electrical conversion technology.

Analysis shows that replacing the Juno power system and propulsion with APPLE would reduce the power system mass by over 80% and transit time by 90%. The new radiation-hard battery being developed jointly between Oak Ridge National Labs (ORNL) and the Aerospace Corporation makes this architecture feasible.

The power system uses the radiation-hard battery to enable close contact with the radioisotope source for waste heat utilization without impacting electrical conversion efficiency, while utilizing the large sail area to efficiently dissipate heat. Using thermal (heat distribution analysis), Monte Carlo (radiation deposition analysis) modeling with CAD (integration geometries) coupled with space power systems simulations, we will show the technical feasibility of the APPLE concept.

We will explore launch safety compatibility by fabricating the radiation hard battery on MMRTG fuel cladding coupons at ORNL. We then will apply the APPLE concept to candidate missions (e.g. Pluto/moons) to ascertain mission advantages over a traditional deep space mission approach (e.g. New Horizon).

The rapid transit times afforded by solar sail propulsion, enabled by APPLE will unleash many significant new deep space missions for science investigation which will inspire the public with images of worlds never seen.

2021 Phase I Selections

About NIAC

The NASA Innovative Advanced Concepts (NIAC) Program nurtures visionary ideas that could transform future NASA missions with the creation of breakthroughs — radically better or entirely new aerospace concepts — while engaging America’s innovators and entrepreneurs as partners in the journey.

The program seeks innovations from diverse and non-traditional sources and NIAC projects study innovative, technically credible, advanced concepts that could one day “change the possible” in aerospace. If you’re interested in submitting a proposal to NIAC, please see our “Apply to NIAC” link ( for information about the status of our current NASA Research Announcement (NRA). For descriptions of current NIAC projects, please refer to our ”NIAC Studies” link (

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