Going Faster

This theme will explore ideas for accelerating mission development with emphasis on the operations phase. We will review the propulsion technologies currently available to reach any destination targets in the Solar System beyond Earth, and those under study/development that could be contemplated for missions beyond the 2040’s-2050’s. One way to go faster is to shorten the transfer time from Earth to the destination target, i.e. by flying faster. Flying faster most likely means arriving faster at the target, hence it requires more efficient ways to slow down for either getting into orbit, direct landing (retro-propulsion), or aero-entry. Currently, two in-space propulsion systems exist: Chemical propulsion (high thrust, low ISP), and electrical propulsion (low thrust, high ISP). The VASIMR concept under development in the US is a promising alternative to both chemical and electrical propulsion, but requires a large electrical power source (at least 100’s kW) for operation far from the Sun (a small nuclear reactor?). If using chemical propulsion for capturing a vehicle arriving on a fast trajectory in orbit around the target, a more capable chemical propulsion system will be required. Alternatively, the use of the promising aero-capture technology should be developed before being envisaged. An aero-entry maneuver from a fast trajectory requires a large heatshield and the aero-thermodynamics entry conditions will be harsher. Aero-capture consists in an autonomously guided single trajectory through the upper layers of an atmosphere that places the spacecraft into an atmospheric exit trajectory that establishes a final low orbit around the planet. Aero-capture has only been successfully tested once by the Soviets in the 60’s (Zond 2 project, reference to be verified/provided). Solar sailing (photonic sail) is a potential low-thrust, high-ISP propulsion technology for the outer solar system. The nascent Electric Sail (E-sail) concept invented by finish researchers in the mid 2000’s, but still in its infancy development, also a low-thrust high-ISP propulsion technology, promises far superior capabilities than the photonic sail and would allow fast direct trajectories to the outer planets or beyond. Dynamic and electro-dynamic Tether systems are potential means for in-space propulsion technology developments. Laser propulsion of light-weight nano/pico-spacecraft is also a potential technology.

 

Mars missions: Current architectures for robotic Mars missions use days- to weeks-long launch windows occurring every about 2 years, when the proper configuration of the two planets, Earth and Mars, is available. Missions to Mars use either direct entry (atmospheric entry under an aero-shell), or capture in an elliptical orbit by chemical propulsion, eventually followed by an aero-breaking maneuvre. An aerobraking maneuvre, that takes place after initial orbit insertion, consists in flying repeatedly through the upper layers of the atmosphere to place the spacecraft in its operational orbit. The first manned missions, anticipated in the 2030-2040’s, would most likely use a direct entry that would require a large aero-shell. The to-be-developed Aero-capture technology may be of benefit to get into an operational orbit or to slow down in two phases prior to entry inside an aero-shell.

Outerplanet missions: The “simplest” way to fly fast to the outer planets is to go on a direct trajectory. Current launcher capabilities may allow a direct trajectory to Jupiter (e. g. Voyagers, Ulysses, New Horizons). Beyond Jupiter, a gravity assist (GA) maneuver at Jupiter (when the proper configuration of Jupiter and the further destination is available) would be required to fly to either Saturn, Uranus, Neptune and beyond. Suitable windows become available about every xx years. A combination of chemical propulsion, electrical propulsion, and Jupiter GA would be worth exploring in details for outer planet destinations beyond Jupiter. Trajectories that include (one or more) GA maneuver(s) at Venus, followed by one or more GA at Earth are currently state-of-the art to get to Jupiter and beyond with a heavy spacecraft (ex. Cassini-Huygens, and current plans for JUICE and Europa Clipper).

Conference Topics: We will review the state-of-the-art in-space propulsion technologies currently available and those in development or in the conceptual stage. For accelerating future robotic and manned Mars missions, and those in the outer solar system, one needs to explore the capabilities of the new-in space propulsion technologies, including the aero-capture technology. New innovative concepts, in particular for distant outer solar system destinations will also be addressed.

Preparatory workshops topics: We shall focus on innovative in-space propulsion concepts: aero-capture, solar sail, E-sail, tether systems, laser propulsion of pico/nano-spacecraft.

Conference organized by the Air & Space Academy with the support of :