Amara Graps - Profile on Academia.edu (original) (raw)

Papers by Amara Graps

arXiv: Earth and Planetary Astrophysics, 2019

In keeping with the Luxembourg government's initiative to support the future use of space res... more In keeping with the Luxembourg government's initiative to support the future use of space resources, ASIME 2018 was held in Belval, Luxembourg on April 16-17, 2018. The goal of ASIME 2018: Asteroid Intersections with Mine Engineering, was to focus on asteroid composition for advancing the asteroid in-space resource utilisation domain. What do we know about asteroid composition from remote-sensing observations? What are the potential caveats in the interpretation of Earth-based spectral observations? What are the next steps to improve our knowledge on asteroid composition by means of ground-based and space-based observations and asteroid rendez-vous and sample return missions? How can asteroid mining companies use this knowledge? ASIME 2018 was a two-day workshop of almost 70 scientists and engineers in the context of the engineering needs of space missions with in-space asteroid utilisation. The 21 Questions from the asteroid mining companies were sorted into the four asteroid s...

arXiv: Earth and Planetary Astrophysics, 2016

The aim of the Asteroid Science Intersections with In-Space Mine Engineering (ASIME) 2016 confere... more The aim of the Asteroid Science Intersections with In-Space Mine Engineering (ASIME) 2016 conference on September 21-22, 2016 in Luxembourg City was to provide an environment for the detailed discussion of the specific properties of asteroids, with the engineering needs of space missions that utilize asteroids. The ASIME 2016 Conference produced a layered record of discussions from the asteroid scientists and the asteroid miners to understand each other's key concerns and to address key scientific questions from the asteroid mining companies: Planetary Resources, Deep Space Industries and TransAstra. These Questions were the focus of the two day conference, were addressed by scientists inside and outside of the ASIME Conference and are the focus of this White Paper. The Questions from the asteroid mining companies have been sorted into the three asteroid science themes: 1) survey, 2) surface and 3) subsurface and 4) Other. The answers to those Questions have been provided by the...

The Jovian dust streams are high-speed bursts of submicron-sized particles traveling in the same ... more The Jovian dust streams are high-speed bursts of submicron-sized particles traveling in the same direction from a source in the Jovian system. Since their discovery in 1992, they have been observed by three spacecraft: Ulysses, Galileo and Cassini. The source of the Jovian dust streams is dust from Io’s volcanoes. The charged and traveling dust stream particles have particular signature s in frequency space and in real space. The frequencytransformed Galileo dust stream measurements show different signatures, varying orbit-to-orbit during Galileo ’s first 29 orbits around Jupiter. Time-frequency analysis demonstrates that Io is a localized source of charged dust particles. Aspects of the particles’ dynamics can be seen in the December 2000 joint Galileo-Cassini dust stream measurements. To match the travel times, the smallest dust particles could have the following range of parameters: radius: 6 nm, density: 1.35–1.75 g/cm , sulfur charging conditions, which produce dust stream spee...

Managing Planetary Dust During Surface Operations

Bulletin of the AAS, 2021

Electrostatic dust charging and subsequent transport on the lunar surface due to direct exposure ... more Electrostatic dust charging and subsequent transport on the lunar surface due to direct exposure to the solar wind plasma and solar radiation is a more than five-decade-old problem. Dust activity has been suggested as an explanation for several lunar surface observations from the beginning in the Apollo era. Beyond the Moon, related observations indicate that this electrostatic process may be a universal phenomenon on airless bodies across the solar system. Recent studies have made important breakthroughs in understanding the fundamentals of dust charging, mobilization and lofting mechanisms, offering strong support for its occurrence on the surfaces of airless bodies. This white paper reviews historical and recent observational evidence, reports recent findings, examines knowledge gaps and outstanding science questions, and provides recommendations for future studies. Special attention is given to in situ measurements over the next decade in order to ultimately solve the outstanding questions and, more importantly, understand the primary implications for the evolution of the surfaces of the Moon and other airless bodies across the solar system. Furthermore, potential risks posed by electrostatic dust transport to future surface exploration of these bodies, especially any long-term human presence on the lunar surface, needs to be well characterized in order to define and implement appropriate risk mitigation strategies and methods through proper systems design and testing.

Bulletin of the AAS, 2021

Interplanetary and Interstellar dust as wIndows Into solar system orIgIns and evolutIon We can ex... more Interplanetary and Interstellar dust as wIndows Into solar system orIgIns and evolutIon We can explore in situ the building blocks of the planets by measuring the trajectories and compositions of thousands of dust particles from comets and our interstellar neighborhood, a full survey of our "dust sky."

Nature, 2000

Streams of dust emerging from the direction of Jupiter were discovered in 1992 during the ¯yby of... more Streams of dust emerging from the direction of Jupiter were discovered in 1992 during the ¯yby of the Ulysses spacecraft 1,2 , but their precise origin within the jovian system remained unclear 2 . Further data 3±5 collected by the Galileo spacecraft, which has been orbiting Jupiter since December 1995, identi®ed the possible sources of dust as Jupiter's main ring 6 , its gossamer ring comet Shoemaker±Levy 9 (ref. 8) and Io. All but Jupiter's gossamer ring and Io have since been ruled out 4,9±14 . Here we ®nd that the dominant source of the jovian dust streams is Io, on the basis of periodicities in the dust impact signal. Io's volcanoes, rather than impact ejecta, are the dust sources. The jovian dust stream population detected in the inner satellite region by the Galileo dust detector system (DDS) can be seen in the data's highly variable (over periods of hours) impact rates of submicrometre-sized particles. Using a Lomb±Scargle periodogram 15 , we have transformed, from the time domain to the frequency domain, the ®rst two years (1996±1997) of Galileo DDS impact-rate data while in orbit around Jupiter. Eight peaks are prominent in the frequency range of 0 to 6 cycles d -1 (Fig. ). We interpret these frequency peaks on the basis of the following description of our physical system (see Fig. ). Io, with its ,42-h rotation period, provides material from its volcanic plumes (up to ,460 km in height ). Material escapes Io at an approximate rate of 1 ton s -1 (ref. 17), through a multistep process involving Io's atmosphere and the local plasma environment . If the charge is high enough, some material can be swept up by Jupiter's magnetic ®eld, which orbits with Jupiter with a ,10-h rotation period . Galileo's and Io's orbits lie very nearly in Jupiter's equatorial plane (within 18). Owing to a 108 tilt between Jupiter's rotational and magnetic axis, Io and Galileo pierce Jupiter's magnetic equatorial plane twice each orbit. Because charged dust couples to Jupiter's magnetic ®eld, which co-rotates with Jupiter (frequency 2.4 d -1 ), Jupiter modulates the rate at which dust particles emerging from Io (frequency 0.6 d -1 ) can be detected. Galileo's dust detector records these charged particles when Jupiter's warped dust sheet passes over its position, which occurs on average twice per Jupiter rotation (4.8 d -1 ). We interpret the frequency peaks seen in Fig. to be the result of Io's frequency of rotation, Jupiter's magnetic ®eld frequency of rotation and an interaction between these two frequencies called amplitude modulation. The simplest case of amplitude modulation is a sinusoid modulating the amplitude of a carrier signal, which is itself a sinusoid. Then the carrier signal is broken down in frequency space into several sinusoidal oscillations: x < sinq 0 t sinq 0 tsint, which can be converted to sums of frequencies using a trigonometric identity for sine products. The result is a signature in frequency space that displays a carrier frequency, q 0 , with side frequencies (`modulation products'), (q 0 ) and (q 0 2 ). Jupiter's modulation of Io's frequency signal can be seen as sidelobes around Jupiter's rotation frequency (Q 0 2:4 d 2 1 ), with the pattern repeated at the ®rst harmonic of M

Caroline: A Search for the Source of Earth's Water

Bulletin of the AAS, 2021

A significant opportunity for synergy between pure research and asteroid resource research exists... more A significant opportunity for synergy between pure research and asteroid resource research exists. We provide an overview of the state of the art in asteroid resource utilization, and highlight where we can accelerate the closing of knowledge gaps, leading to the utilization of asteroid resources for growing economic productivity in space.

Advances in Space Research

We describe Caroline, a mission proposal submitted to the European Space Agency in 2010 in respon... more We describe Caroline, a mission proposal submitted to the European Space Agency in 2010 in response to the Cosmic Visions M3 call for medium-sized missions. Caroline would have travelled to a Main Belt Comet (MBC), characterizing the object during a flyby, and capturing dust from its tenuous coma for return to Earth. MBCs are suspected to be transition objects straddling the traditional boundary between volatile-poor rocky asteroids and volatile-rich comets. The weak cometary activity exhibited by these objects indicates the presence of water ice, and may represent the primary type of object that delivered water to the early Earth. The Caroline mission would have employed aerogel as a medium for the capture of dust grains, as successfully used by the NASA Stardust mission to Comet 81P/ Wild 2. We describe the proposed mission design, primary elements of the spacecraft, and provide an overview of the science instruments and their measurement goals. Caroline was ultimately not selected by the European Space Agency during the M3 call; we briefly reflect on the pros and cons of the mission as proposed, and how current and future mission MBC mission proposals such as Castalia could best be approached.

Meteoroids 2001 Conference, Nov 1, 2001

The Jovian dust streams are high-speed bursts of submicron-sized particles traveling in the same ... more The Jovian dust streams are high-speed bursts of submicron-sized particles traveling in the same direction from a source in the Jovian system. Since their discovery in 1992, they have been observed by three spacecraft: Ulysses, Galileo and Cassini. The source of the Jovian dust streams is dust from Io's volcanoes. The charged and traveling dust stream particles have particular signatures in frequency space and in real space. The frequencytransformed Galileo dust stream measurements show different signatures, varying orbit-to-orbit during Galileo's first 29 orbits around Jupiter. Time-frequency analysis demonstrates that Io is a localized source of charged dust particles. Aspects of the particles' dynamics can be seen in the December 2000 joint Galileo-Cassini dust stream measurements. To match the travel times, the smallest dust particles could have the following range of parameters: radius: 6 nm, density: 1.35-1.75 g/cm 3 , sulfur charging conditions, which produce dust stream speeds: 220\450 km s −1 (Galileo\Cassini) and charge potentials: 5.5\6.3 V (Galileo\Cassini).

Watering the Earth

Despite our living embedded in the Earth environment, the origin of water on Earth is one of the ... more Despite our living embedded in the Earth environment, the origin of water on Earth is one of the most puzzling enigmas in the planetary sciences. Our planet that spawned our watery origins presently carries enough surface water in vapor or liquid form to cover the entire planet to a depth of about 3 km. Earth has substantially more water than

Dusty Phenomena in the Solar System

Sky and Telescope, 2001

The Galileo spacecraft was the first man-made satellite of Jupiter, orbiting the 8 planet between... more The Galileo spacecraft was the first man-made satellite of Jupiter, orbiting the 8 planet between December 1995 and September 2003. The spacecraft was equipped 9 with a highly sensitive dust detector that monitored the jovian dust environment be-10

Planetary and Space Science, 2006

The Galileo spacecraft was the first man-made satellite of Jupiter, orbiting the 8 planet between... more The Galileo spacecraft was the first man-made satellite of Jupiter, orbiting the 8 planet between December 1995 and September 2003. The spacecraft was equipped 9 with a highly sensitive dust detector that monitored the jovian dust environment be-10

Jupiter dust stream observations with Cassini

Max-Planck-Institut fr …, 2000

... Ralf Srama∗, James Bradley†, Marcia Burton†, Valeri Dikarev, Amara Graps, Eberhard Grün, Andr... more ... Ralf Srama∗, James Bradley†, Marcia Burton†, Valeri Dikarev, Amara Graps, Eberhard Grün, Andreas Heck, Stefan Helfert, Torrence Johnson ... offers the possibility to observe and characterize the Jovian dust stream discovered by the dust detectors onboard Galileo and Ulysses. ...

The Cassini-Huygens cosmic dust analyzer (CDA) is intended to provide direct observa-40 tions of ... more The Cassini-Huygens cosmic dust analyzer (CDA) is intended to provide direct observa-40 tions of dust grains with masses between 10 −19 and 10 −9 kg in interplanetary space and in the Jovian 41

arXiv: Earth and Planetary Astrophysics, 2019

In keeping with the Luxembourg government's initiative to support the future use of space res... more In keeping with the Luxembourg government's initiative to support the future use of space resources, ASIME 2018 was held in Belval, Luxembourg on April 16-17, 2018. The goal of ASIME 2018: Asteroid Intersections with Mine Engineering, was to focus on asteroid composition for advancing the asteroid in-space resource utilisation domain. What do we know about asteroid composition from remote-sensing observations? What are the potential caveats in the interpretation of Earth-based spectral observations? What are the next steps to improve our knowledge on asteroid composition by means of ground-based and space-based observations and asteroid rendez-vous and sample return missions? How can asteroid mining companies use this knowledge? ASIME 2018 was a two-day workshop of almost 70 scientists and engineers in the context of the engineering needs of space missions with in-space asteroid utilisation. The 21 Questions from the asteroid mining companies were sorted into the four asteroid s...

arXiv: Earth and Planetary Astrophysics, 2016

The aim of the Asteroid Science Intersections with In-Space Mine Engineering (ASIME) 2016 confere... more The aim of the Asteroid Science Intersections with In-Space Mine Engineering (ASIME) 2016 conference on September 21-22, 2016 in Luxembourg City was to provide an environment for the detailed discussion of the specific properties of asteroids, with the engineering needs of space missions that utilize asteroids. The ASIME 2016 Conference produced a layered record of discussions from the asteroid scientists and the asteroid miners to understand each other's key concerns and to address key scientific questions from the asteroid mining companies: Planetary Resources, Deep Space Industries and TransAstra. These Questions were the focus of the two day conference, were addressed by scientists inside and outside of the ASIME Conference and are the focus of this White Paper. The Questions from the asteroid mining companies have been sorted into the three asteroid science themes: 1) survey, 2) surface and 3) subsurface and 4) Other. The answers to those Questions have been provided by the...

The Jovian dust streams are high-speed bursts of submicron-sized particles traveling in the same ... more The Jovian dust streams are high-speed bursts of submicron-sized particles traveling in the same direction from a source in the Jovian system. Since their discovery in 1992, they have been observed by three spacecraft: Ulysses, Galileo and Cassini. The source of the Jovian dust streams is dust from Io’s volcanoes. The charged and traveling dust stream particles have particular signature s in frequency space and in real space. The frequencytransformed Galileo dust stream measurements show different signatures, varying orbit-to-orbit during Galileo ’s first 29 orbits around Jupiter. Time-frequency analysis demonstrates that Io is a localized source of charged dust particles. Aspects of the particles’ dynamics can be seen in the December 2000 joint Galileo-Cassini dust stream measurements. To match the travel times, the smallest dust particles could have the following range of parameters: radius: 6 nm, density: 1.35–1.75 g/cm , sulfur charging conditions, which produce dust stream spee...

Managing Planetary Dust During Surface Operations

Bulletin of the AAS, 2021

Electrostatic dust charging and subsequent transport on the lunar surface due to direct exposure ... more Electrostatic dust charging and subsequent transport on the lunar surface due to direct exposure to the solar wind plasma and solar radiation is a more than five-decade-old problem. Dust activity has been suggested as an explanation for several lunar surface observations from the beginning in the Apollo era. Beyond the Moon, related observations indicate that this electrostatic process may be a universal phenomenon on airless bodies across the solar system. Recent studies have made important breakthroughs in understanding the fundamentals of dust charging, mobilization and lofting mechanisms, offering strong support for its occurrence on the surfaces of airless bodies. This white paper reviews historical and recent observational evidence, reports recent findings, examines knowledge gaps and outstanding science questions, and provides recommendations for future studies. Special attention is given to in situ measurements over the next decade in order to ultimately solve the outstanding questions and, more importantly, understand the primary implications for the evolution of the surfaces of the Moon and other airless bodies across the solar system. Furthermore, potential risks posed by electrostatic dust transport to future surface exploration of these bodies, especially any long-term human presence on the lunar surface, needs to be well characterized in order to define and implement appropriate risk mitigation strategies and methods through proper systems design and testing.

Bulletin of the AAS, 2021

Interplanetary and Interstellar dust as wIndows Into solar system orIgIns and evolutIon We can ex... more Interplanetary and Interstellar dust as wIndows Into solar system orIgIns and evolutIon We can explore in situ the building blocks of the planets by measuring the trajectories and compositions of thousands of dust particles from comets and our interstellar neighborhood, a full survey of our "dust sky."

Nature, 2000

Streams of dust emerging from the direction of Jupiter were discovered in 1992 during the ¯yby of... more Streams of dust emerging from the direction of Jupiter were discovered in 1992 during the ¯yby of the Ulysses spacecraft 1,2 , but their precise origin within the jovian system remained unclear 2 . Further data 3±5 collected by the Galileo spacecraft, which has been orbiting Jupiter since December 1995, identi®ed the possible sources of dust as Jupiter's main ring 6 , its gossamer ring comet Shoemaker±Levy 9 (ref. 8) and Io. All but Jupiter's gossamer ring and Io have since been ruled out 4,9±14 . Here we ®nd that the dominant source of the jovian dust streams is Io, on the basis of periodicities in the dust impact signal. Io's volcanoes, rather than impact ejecta, are the dust sources. The jovian dust stream population detected in the inner satellite region by the Galileo dust detector system (DDS) can be seen in the data's highly variable (over periods of hours) impact rates of submicrometre-sized particles. Using a Lomb±Scargle periodogram 15 , we have transformed, from the time domain to the frequency domain, the ®rst two years (1996±1997) of Galileo DDS impact-rate data while in orbit around Jupiter. Eight peaks are prominent in the frequency range of 0 to 6 cycles d -1 (Fig. ). We interpret these frequency peaks on the basis of the following description of our physical system (see Fig. ). Io, with its ,42-h rotation period, provides material from its volcanic plumes (up to ,460 km in height ). Material escapes Io at an approximate rate of 1 ton s -1 (ref. 17), through a multistep process involving Io's atmosphere and the local plasma environment . If the charge is high enough, some material can be swept up by Jupiter's magnetic ®eld, which orbits with Jupiter with a ,10-h rotation period . Galileo's and Io's orbits lie very nearly in Jupiter's equatorial plane (within 18). Owing to a 108 tilt between Jupiter's rotational and magnetic axis, Io and Galileo pierce Jupiter's magnetic equatorial plane twice each orbit. Because charged dust couples to Jupiter's magnetic ®eld, which co-rotates with Jupiter (frequency 2.4 d -1 ), Jupiter modulates the rate at which dust particles emerging from Io (frequency 0.6 d -1 ) can be detected. Galileo's dust detector records these charged particles when Jupiter's warped dust sheet passes over its position, which occurs on average twice per Jupiter rotation (4.8 d -1 ). We interpret the frequency peaks seen in Fig. to be the result of Io's frequency of rotation, Jupiter's magnetic ®eld frequency of rotation and an interaction between these two frequencies called amplitude modulation. The simplest case of amplitude modulation is a sinusoid modulating the amplitude of a carrier signal, which is itself a sinusoid. Then the carrier signal is broken down in frequency space into several sinusoidal oscillations: x < sinq 0 t sinq 0 tsint, which can be converted to sums of frequencies using a trigonometric identity for sine products. The result is a signature in frequency space that displays a carrier frequency, q 0 , with side frequencies (`modulation products'), (q 0 ) and (q 0 2 ). Jupiter's modulation of Io's frequency signal can be seen as sidelobes around Jupiter's rotation frequency (Q 0 2:4 d 2 1 ), with the pattern repeated at the ®rst harmonic of M

Caroline: A Search for the Source of Earth's Water

Bulletin of the AAS, 2021

A significant opportunity for synergy between pure research and asteroid resource research exists... more A significant opportunity for synergy between pure research and asteroid resource research exists. We provide an overview of the state of the art in asteroid resource utilization, and highlight where we can accelerate the closing of knowledge gaps, leading to the utilization of asteroid resources for growing economic productivity in space.

Advances in Space Research

We describe Caroline, a mission proposal submitted to the European Space Agency in 2010 in respon... more We describe Caroline, a mission proposal submitted to the European Space Agency in 2010 in response to the Cosmic Visions M3 call for medium-sized missions. Caroline would have travelled to a Main Belt Comet (MBC), characterizing the object during a flyby, and capturing dust from its tenuous coma for return to Earth. MBCs are suspected to be transition objects straddling the traditional boundary between volatile-poor rocky asteroids and volatile-rich comets. The weak cometary activity exhibited by these objects indicates the presence of water ice, and may represent the primary type of object that delivered water to the early Earth. The Caroline mission would have employed aerogel as a medium for the capture of dust grains, as successfully used by the NASA Stardust mission to Comet 81P/ Wild 2. We describe the proposed mission design, primary elements of the spacecraft, and provide an overview of the science instruments and their measurement goals. Caroline was ultimately not selected by the European Space Agency during the M3 call; we briefly reflect on the pros and cons of the mission as proposed, and how current and future mission MBC mission proposals such as Castalia could best be approached.

Meteoroids 2001 Conference, Nov 1, 2001

The Jovian dust streams are high-speed bursts of submicron-sized particles traveling in the same ... more The Jovian dust streams are high-speed bursts of submicron-sized particles traveling in the same direction from a source in the Jovian system. Since their discovery in 1992, they have been observed by three spacecraft: Ulysses, Galileo and Cassini. The source of the Jovian dust streams is dust from Io's volcanoes. The charged and traveling dust stream particles have particular signatures in frequency space and in real space. The frequencytransformed Galileo dust stream measurements show different signatures, varying orbit-to-orbit during Galileo's first 29 orbits around Jupiter. Time-frequency analysis demonstrates that Io is a localized source of charged dust particles. Aspects of the particles' dynamics can be seen in the December 2000 joint Galileo-Cassini dust stream measurements. To match the travel times, the smallest dust particles could have the following range of parameters: radius: 6 nm, density: 1.35-1.75 g/cm 3 , sulfur charging conditions, which produce dust stream speeds: 220\450 km s −1 (Galileo\Cassini) and charge potentials: 5.5\6.3 V (Galileo\Cassini).

Watering the Earth

Despite our living embedded in the Earth environment, the origin of water on Earth is one of the ... more Despite our living embedded in the Earth environment, the origin of water on Earth is one of the most puzzling enigmas in the planetary sciences. Our planet that spawned our watery origins presently carries enough surface water in vapor or liquid form to cover the entire planet to a depth of about 3 km. Earth has substantially more water than

Dusty Phenomena in the Solar System

Sky and Telescope, 2001

The Galileo spacecraft was the first man-made satellite of Jupiter, orbiting the 8 planet between... more The Galileo spacecraft was the first man-made satellite of Jupiter, orbiting the 8 planet between December 1995 and September 2003. The spacecraft was equipped 9 with a highly sensitive dust detector that monitored the jovian dust environment be-10

Planetary and Space Science, 2006

The Galileo spacecraft was the first man-made satellite of Jupiter, orbiting the 8 planet between... more The Galileo spacecraft was the first man-made satellite of Jupiter, orbiting the 8 planet between December 1995 and September 2003. The spacecraft was equipped 9 with a highly sensitive dust detector that monitored the jovian dust environment be-10

Jupiter dust stream observations with Cassini

Max-Planck-Institut fr …, 2000

... Ralf Srama∗, James Bradley†, Marcia Burton†, Valeri Dikarev, Amara Graps, Eberhard Grün, Andr... more ... Ralf Srama∗, James Bradley†, Marcia Burton†, Valeri Dikarev, Amara Graps, Eberhard Grün, Andreas Heck, Stefan Helfert, Torrence Johnson ... offers the possibility to observe and characterize the Jovian dust stream discovered by the dust detectors onboard Galileo and Ulysses. ...

The Cassini-Huygens cosmic dust analyzer (CDA) is intended to provide direct observa-40 tions of ... more The Cassini-Huygens cosmic dust analyzer (CDA) is intended to provide direct observa-40 tions of dust grains with masses between 10 −19 and 10 −9 kg in interplanetary space and in the Jovian 41