Technology requirements of exploration beyond Neptune by solar sail propulsion

This paper provides a set of requirements for the technology development of a solar sail propelled Interstellar Heliopause Probe mission. The mission is placed in the context of other outer solar systems missions, ranging from a Kuiper Belt mission through to an Oort cloud mission. Mission requirements are defined and a detailed parametric trajectory analysis and launch date scan performed. Through analysis of the complete mission trade space a set of critical technology development requirements are identified which include an advanced lightweight composite High-Gain Antenna, a high-efficiency Ka-band travelling-wave tube amplifier and a radioisotope thermoelectric generator with power density of approximately 12 W/kg. It is also shown that the Interstellar Heliopause Probe mission necessitates the use of a spinning sail, limiting the direct application of current hardware development activities. A Kuiper Belt mission is then considered as a pre-curser to the Interstellar Heliopause Probe, while it is also shown through study of an Oort cloud mission that the Interstellar Heliopause Probe mission is the likely end-goal of any future solar sail technology development program. As such, the technology requirements identified to enable the Interstellar Heliopause Probe must be enabled through all prior missions, with each mission acting as an enabling facilitator towards the next

Heliocentric solar sail orbit transfers with locally optimal control laws

Solar sailing is increasingly being considered by space agencies for future science missions. With the absence of reaction mass from the primary propulsion system arises the potential for new high-energy mission concepts in the mid to far term, such as a Solar Polar Orbiter or an Interstellar Heliopause Probe [1,2]. One of the most time consuming tasks of mission analysis is trajectory generation and optimization. Optimal trajectory generation is a complex field and many schemes exist; however, these are typically characterized as being computationally intensive systems requiring a good degree of engineering judgment [3-6]

What Makes a Good (Computed) Energy Profile?

International audienceA good meal cannot be defined in an absolute manner since it depends strongly on where and how it is eaten and how many people participate. A picnic shared by hikers after a challenging climbing is very different from a birthday party among a family or a banquet for a large convention. All of them can be memorable and also good. The same perspective applies to computational studies. Required level of calculations for spectroscopic properties of small molecular systems and properties of medium or large organic or organometallic, polymetallic systems are different. To well-specified chemical questions and chemical systems, efficient computational strategies can be established. In this chapter, the focus is on the energy profile representation of stoichiometric or catalytic reactions assisted by organometallic molecular entities. The multiple factors that can influence the quality of the calculations of the Gibbs energy profile and thus the mechanistic interpretation of reactions with molecular organometallic complexes are presented and illustrated by examples issued from mostly personal studies. The usual suspects to be discussed are known: representation of molecular models of increasing size, conformational and chemical complexity, methods and levels of calculations, successes and limitations of the density functional methods, thermodynamics corrections, spectator or actor role of the solvent, and static vs dynamics approaches. These well-identified points of concern are illustrated by presentation of computational studies of chemical reactions which are in direct connection with experimental data. Even if problems persist, this chapter aims at illustrating that one can reach a representation of the chemical reality that can be useful to address questions of present chemical interest. Computational chemistry is already well armed to bring meaningful energy information to numerous well-defined questions