Low-cost precursor of an interstellar mission

Abstract

The solar photon pressure provides a viable source of thrust for spacecraft in the solar system. Theoretically it could also enable interstellar missions, but an extremely small mass per cross section area is required to overcome the solar gravity. We identify aerographite, a synthetic carbon-based foam with a density of 0.18 kg m−3 (15 000 times more lightweight than aluminum) as a versatile material for highly efficient propulsion with sunlight. A hollow aerographite sphere with a shell thickness ϵshl = 1 mm could go interstellar upon submission to solar radiation in interplanetary space. Upon launch at 1 AU from the Sun, an aerographite shell with ϵshl = 0.5 mm arrives at the orbit of Mars in 60 d and at Pluto’s orbit in 4.3 yr. Release of an aerographite hollow sphere, whose shell is 1 μm thick, at 0.04 AU (the closest approach of the Parker Solar Probe) results in an escape speed of nearly 6900 km s−1 and 185 yr of travel to the distance of our nearest star, Proxima Centauri. The infrared signature of a meter-sized aerographite sail could be observed with JWST up to 2 AU from the Sun, beyond the orbit of Mars. An aerographite hollow sphere, whose shell is 100 μm thick, of 1 m (5 m) radius weighs 230 mg (5.7 g) and has a 2.2 g (55 g) mass margin to allow interstellar escape. The payload margin is ten times the mass of the spacecraft, whereas the payload on chemical interstellar rockets is typically a thousandth of the weight of the rocket. Using 1 g (10 g) of this margin (e.g., for miniature communication technology with Earth), it would reach the orbit of Pluto 4.7 yr (2.8 yr) after interplanetary launch at 1 AU. Simplistic communication would enable studies of the interplanetary medium and a search for the suspected Planet Nine, and would serve as a precursor mission to α Centauri. We estimate prototype developments costs of 1 million USD, a price of 1000 USD per sail, and a total of < 10 million USD including launch for a piggyback concept with an interplanetary mission.

Understanding the trans-Neptunian Solar system; Reconciling the results of serendipitous stellar occultations and the inferences from the cratering record.

“…For future proposed missions to the outer Solar system (e.g., McNutt et al 2019;Heller et al 2020;Turyshev et al 2020), it could be possible detect an extended cold belt. If the mission is close to the ecliptic, the brightest member would have an apparent magnitude of ∼ 13 in the best fit model.…”

Wind--Pellet Shear Sailing

“…An alternative energy source is the photon flux near the sun. Hollow aerographite pellets offer a low effective density and, if released close to the sun, can reach up to 2% of c [32]. These pellets would again be hollow spheres.…”

“…Pellet dispenser launch T+0 years Spacecraft stack launch (dynamic soaring [31] The earlier stage of propulsion invoking wind-pellet shear sailing, under the same assumptions, has a 15 000-kg mass for the propulsion hardware of that stage and hence a 30 000-kg total mass at the end of the wind-pellet shear sailing maneuver. For simplicity of analysis, consider the pellets to be launched by photon pressure from a dispenser in close proximity to the Sun, for example, as aerographite hollow spheres [32]. This approach gives a 2% of c pellet speed and using the same assumption of 5% energy loss to parasitic drag, ≈240,000 kg of pellets would be required to accelerate the stage from 2% of c to 5.5% of c. If dynamic soaring at the solar-wind termination shock is used [31], similar results would be obtained by a series of dispenser craft.…”

Electric Propulsion Methods for Small Satellites: A Review

“…Materials such as aerogel films were proposed by [117], however creating ultrathin aerogel films is challenging, though a flexible, freestanding, easily fabricated graphene-based aerogel film has been proposed by [118]. Some recent models of materials from an EU based research group predict that aero-graphite could offer an alternative to laser driven sail by approaching the sun at 0.4 AU with such a light material that could result in speeds of up to 6900 km/s −1 [119]. A recent demonstration of how laser light can manipulate mechanical processes of tiny optical nanomachines could be very advantageous.…”