Distinguished EPJ Referees

EPJ ST Highlight – Introduction to Celestial Mechanics in the XXIst Century

Space exploration is moving into a new era, the turn of the century has seen past glories fade and the focus of science and research move from one-off achievements and firsts, to the establishment of frameworks that will encourage sustainability. At the same time, the more we learn about space, the more we realise that plans must be put in place to mitigate threats from beyond our own atmosphere. As such, the EPJ Special Topics issue on ‘Celestial Mechanics in the XXIst Century’ reflects this shift in attention by spotlighting research that aims to cement humankind’s place amongst the stars.

Here, we present highlights from this issue where we learn how spacecrafts can get a boost in ‘Aerogravity Assisted’ interactions, how we might reduce the risk of space debris collision, and how a tethered diversion might protect Earth from asteroid impact.

EPJ ST Highlight - Spacecrafts get a boost in ‘Aerogravity Assisted’ interactions

The Voyager 2 probe gained the energy boost to escape the solar system from an AGA (NASA/JPL)

New research examines the effect of rotation and other variables in the applications of ‘aerogravity assisted’ manoeuvres to obtain an energy boost for space craft.

In a recent paper published in EPJ Special Topics, Jhonathan O. Murcia Piñeros, a post-doctoral researcher at Space Electronics Division, Instituto Nacional de Pesquisas Espaciais, São José dos Campos, Brazil, and his co-authors, map the energy variations of the spacecraft orbits during ‘aerogravity assisted’ (AGA) manoeuvres. A technique in which energy gains are granted to a spacecraft by a close encounter with a planet or other celestial body via that body’s atmosphere and gravity.

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EPJ ST Highlight - Reducing the risk of space debris collision

Debris plot by NASA / Public Domain

An increase in space launches requires the development of a method to clear space debris which could collide with valuable equipment. One plausible method of achieving this through the use of a tug vehicle requires a successful connection procedure.

As humanity expands its horizons beyond the Earth and begins to consider space missions with extended duration, sustainability necessitates the launch of more space vehicles, increasing the risk of collision with existing space debris. One method of clearing this debris involves a tug vehicle dragging it to a safe region. In a new paper published in EPJ Special Topics, authors Antônio Delson Conceição de Jesus and Gabriel Luiz F. Santos, both from the State University of Feira de Santana, Bahia, Brazil, model the complex rendezvous manoeuvres a tug vehicle clearing space debris would have to undergo to mitigate the risk of a collision that could cause irreparable damage at the moment of coupling.

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EPJ ST Highlight - Protecting Earth from asteroid impact with a tethered diversion

A depiction of a tether connecting two asteroids

The use of a tether assisted system could prevent an asteroid impacting Earth without the risk of fragmentation.

Our planet exists within the vicinity of thousands of Near-Earth Objects (NEOs), some of which –  Potentially Hazardous Asteroids (PHAs)  –  carry the risk of impacting Earth causing major damage to infrastructure and loss of life. Methods to mitigate such a collision are highly desirable. A new paper published in EPJ Special Topics, authored by Flaviane Venditti, Planetary Radar Department, Arecibo Observatory, University of Central Florida, Arecibo, suggests the use of a tether assisted system to prevent PHA impact.

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EPJ ST Highlight - Exploring strangeness and the primordial Universe

Having studied quark-gluon plasma since the late 1970s, Dr Johann Rafelski summarises the evolution in our understanding of the exotic quark signature of this primordial material which once filled the whole Universe.

Physicists believe that in the Universe’s first ten microseconds free quarks and gluons filled all of spacetime, forming a new phase of matter named ‘quark-gluon plasma’ (QGP). Experimental and theoretical work at CERN was instrumental in the discovery of this hot soup of primordial matter, which is recreated today in accelerator-based lab experiments. To discover QGP in such experiments, the observation of exotic ‘strange’ quarks is very important. If QGP is created, strangeness is readily produced through collisions between gluons. In analysis published in EPJ Special Topics, Dr Johann Rafelski from The University of Arizona, United States, also working at CERN, presents how our understanding of this characteristic strangeness production signature has evolved over the span of his long career.

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EPJ ST Highlight - Infinite number of quantum particles gives clues to big-picture behaviour at large scale

Werner Heisenberg. Bundesarchiv, Bild 183-R57262 / Unknown / CC-BY-SA 3.0 [CC BY-SA 3.0 de (https://creativecommons.org/ licenses/by-sa/3.0/de/deed.en)]

Scientists gain a deeper understanding of phenomena at macroscopic scale by simulating the consequences of having an infinite number of physical phenomena at quantum scale

In quantum mechanics, the Heisenberg uncertainty principle prevents an external observer from measuring both the position and speed (referred to as momentum) of a particle at the same time. They can only know with a high degree of certainty either one or the other - unlike what happens at large scales where both are known. To identify a given particle’s characteristics, physicists introduced the notion of quasi-distribution of position and momentum. This approach was an attempt to reconcile quantum-scale interpretation of what is happening in particles with the standard approach used to understand motion at normal scale, a field dubbed classical mechanics.

In a new study published in EPJ Special Topics, Dr J.S. Ben-Benjamin and colleagues from Texas A&M University, USA, reverse this approach; starting with quantum mechanical rules, they explore how to derive an infinite number of quasi-distributions, to emulate the classical mechanics approach. This approach is also applicable to a number of other variables found in quantum-scale particles, including particle spin.

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EPJ ST Highlight - Champagne owes its taste to the finely tuned quality of its bubbles

Flower-shaped structure, frozen through high-speed photography, found during the collapse of bubbles at the surface of a champagne flute.

What provides the wonderful aromas is a long neuro-physico-chemical process that results in bubbles fizzing at the surface of champagne

Ever wondered how the fate of champagne bubbles from their birth to their death with a pop enhances our perception of aromas? These concerns, which are relevant to champagne producers, are the focus of a special issue of EPJ Special Topics, due to be published in early January 2017 - celebrating the 10th anniversary of the publication. Thanks to scientists, champagne producers are now aware of the many neuro-physico-chemical mechanisms responsible for aroma release and flavour perception. The taste results from the complex interplay between the level of CO2 and the agents responsible for the aroma - known as volatile organic compounds - dispersed in champagne bubbles, as well as temperature, glass shape, and bubbling rate.

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EPJ ST Highlight - Economics made simple with physics models

Snapshot of the study of economic phenomena using the tools of physics

How would you go about understanding how markets can suddenly be gripped by panic? To physicists, using a model originally developed to explain magnetism might make sense. Yet, economists may find this extremely counter-intuitive. Both physical and economic phenomena may possess universal features that could be uncovered using the tools of physics. The principal difference is that in economic systems - unlike physical ones - current actions may be influenced by the perception of future events. The latest issue of EPJ Special Topics examines the question as to whether econophysics, a physics-based approach to understanding economic phenomena, is more useful and desirable than conventional economics theories.

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EPJ ST Highlight - Laser-based accelerators: yes, we CAN!

Future ultra-fast high power lasers, dubbed Coherent Amplification Network (CAN) lasers, will deliver unprecedented accelerating power and efficiency

Few technologies have the power that particle accelerator technology has to touch upon such a broad range of applications at the many frontiers of modern science. Today, thanks to improvements in laser technology, a new generation of accelerators could soon emerge to replace accelerators relying on radio frequencies. In this new special issue, the journal EPJ Special Topics explores the requirements necessary to make such laser accelerators a reality, by presenting the work of the International Coherent Amplification Network (ICAN) research collaboration. Potential applications include future colliders, solutions for vacuum physics, design of Higgs-particle factories, creation of sources of high-flux protons and of neutrons, among others. Further, such accelerators open the door to solutions in nuclear pharmacology and proton therapy as well as orbital debris remediation.

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EPJ ST Highlight - Analogue quantum computers: still wishful thinking?

Many challenges lie ahead before quantum annealing, the analogue version of quantum computation, contributes to solve combinatorial optimisation problems

Traditional computational tools are simply not powerful enough to solve some complex optimisation problems, like, for example, protein folding. Quantum annealing, a potentially successful implementation of analogue quantum computing, would bring about an ultra-performant computational method. A series of reviews in this topical issue of EPJ ST, guest-edited by Sei Suzuki from Saitama Medical University, Japan, and Arnab Das from the Indian Association for the Cultivation of Science, Kolkota, India, focuses on the state of the art and challenges in quantum annealing. This approach, if proven viable, could greatly boost the capabilities of large-scale simulations and revolutionise several research fields, from biology to economics, medicine and material science.

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