J. Helbert

J. Helbert
German Aerospace Center (DLR) | DLR · Institute of Planetary Research

Dr.

About

587
Publications
31,724
Reads
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4,253
Citations
Additional affiliations
April 2015 - present
German Aerospace Center (DLR)
Position
  • Group leader - Planetary Spectroscopy Laboratories
November 2012 - April 2013
Brown University
Position
  • Visiting Researcher
September 2012 - November 2012
University of Colorado Boulder
Position
  • Visting Researcher

Publications

Publications (587)
Article
Full-text available
The near-Earth asteroid (162173) Ryugu, the target of Hayabusa2 space mission, was observed via both orbiter and the lander instruments. The infrared radiometer on the MASCOT lander (MARA) is the only instrument providing spectrally resolved mid-infrared (MIR) data, which is crucial for establishing a link between the asteroid material and meteorit...
Article
Full-text available
The last thirty years of cosmochemistry and planetary science have shown that one major Solar System reservoir is vastly undersampled in the available suite of extra-terrestrial materials, namely small bodies that formed in the outer Solar System (>10 AU). Because various dynamical evolutionary processes have modified their initial orbits (e.g., gi...
Article
Full-text available
Planetesimals—the initial stage of the planetary formation process—are considered to be initially very porous aggregates of dusts1,2, and subsequent thermal and compaction processes reduce their porosity3. The Hayabusa2 spacecraft found that boulders on the surface of asteroid (162173) Ryugu have an average porosity of 30–50% (refs. 4–6), higher th...
Article
Full-text available
The plume of Enceladus is unique in the solar system in providing direct access to fresh material from an extraterrestrial subsurface ocean. The Cassini Mission, though not specifically designed for it, was able to take advantage of the plume to conduct the best characterization to date of an extraterrestrial ocean. Evidence gathered from multiple...
Conference Paper
The MErcury Radiometer and Thermal Infrared Spectrometer (MERTIS) is an instrument to study the mineralogy and temperature distribution of Mercury’s surface in unprecedented detail. MERTIS was proposed in 2003 as payload of the Mercury Planetary Orbiter spacecraft of ESA-JAXA BepiColombo mission and will reach Mercury in 2025. MERTIS will map the w...
Conference Paper
Full-text available
Introduction: Laboratory measurements of extra-terrestrial materials like meteorites and ultimately materials from sample return missions can significantly enhance the scientific return of the global remote sensing data. This motivated the addition of a dedicated Sample Analysis Laboratory (SAL) to complement the work of well estab-lished facilitie...
Conference Paper
Introduction: The nature and extent of the first volcanic processes occurring on planetesimals in the early solar system are largely unknown due to a scarcity of meteorites that probe and document these processes. Partial-melting experiments performed with chondritic materials [1] suggest that felsic, andesitic or trachyandesitic partial melts were...
Article
Full-text available
Solar System bodies undergo to daily and periodical variations of temperature that mainly depend on their closeness to the Sun. It is known that mineral expansion and contraction due to such variations modify the thermal infrared spectra acquired on solid surfaces. Therefore, it becomes crucial to know the best temperature range at which the acquis...
Article
Using five band orbital emissivity measurements in the 1 micron region has tremendous potential to provide global maps of Venus surface rock types. Combining this with 480°C laboratory measurement will poise Venus science for a dramatic improvement in understanding of surface geology and the formation and internal processes of Earth’s twin planet.
Article
Full-text available
Venus Corona and Tessera Explorer (VeCaTEx) would use an aerobot to descend repeatedly beneath the dense clouds for imaging targeted area of the surface in the near infrared to address six of the prime investigations prioritized by VEXAG. The technologies needed could be matured during the next decade.
Article
Geodynamics, like Earth’s plate tectonics (PT), governs long-term planetary evolution and habitability. Beyond Earth, only Venus may have key elements of PT: subduction (the 1st step in PT) and continents. Revealing Venus’ geodynamics is key to understanding how PT began on Earth, and how to predict the geodynamic evolution of other rocky bodies.
Article
Understanding Venus will benefit from a dedicated effort through an international program of missions that are coordinated and offering opportunities for coooperation. The recent discovery of phosphene in the Venus clouds and possibility of life will increase the exploration missions and cooperation and coordination will be very benefical.
Article
The plume of Enceladus provides access to fresh material from a habitable, subsurface ocean. We summarize in this white paper the evidence for Enceladus’ ocean and its habitability, identify constraints and outstanding questions on the detectability of life within Enceladus, and recommend a return to Enceladus beginning in the coming decade.
Article
More than 85% of the 23 investigations developed by VEXAG are largely accomplished via a NF mission centered on a variable-altitude balloon (aerobot) supported by a science/comm orbiter. Circling Venus >15 times over ~90 days, the aerobot repeatedly visits 52–62 km alts as it semi-continuously samples a host of environmental & surface parameters.
Article
Full-text available
The Thalassa mission concept was developed in response to the 2019 NASA Planetary Mission Concept Studies call. Using a multi-platform mission architecture, Thalassa seeks to address a single science goal: to determine the extent to which water has played a role in the geological evolution of Venus.
Article
Experimental facilities dedicated to recreating the conditions on the surface of Venus are critical for advancing scientific understanding of the planet and developing the technologies needed to continue Venus exploration. These facilities should be supported and enhanced in the next decade to maximize our efforts to understand this key planet.
Article
Full-text available
Thermophysical properties of the surface of asteroid 162173 Ryugu have been investigated through global, local and close-up thermal imaging from the Hayabusa2 spacecraft using the thermal infrared imager TIR, a two-dimensional thermographic camera. The set of thermal images during one rotation of asteroid allowed to map thermal inertia of the aster...
Article
We conducted classic dynamic high - pressure experiments on porous San Carlos (SC) olivine powder to examine if and how different shock stages modify corresponding reflectance mid – infrared (MIR) spectra. Microscopic investigation of the thin sections produced of our shocked samples indicates local peak pressures of >60 GPa along with all lower gr...
Article
Full-text available
C-type asteroids are among the most pristine objects in the Solar System, but little is known about their interior structure and surface properties. Telescopic thermal infrared observations have so far been interpreted in terms of a regolith-covered surface with low thermal conductivity and particle sizes in the centimetre range. This includes obse...
Article
To detect the mineral diversity of a planet's surface, it is essential to study the spectral variations over a broad wavelength range at relevant simulated laboratory conditions. The MESSENGER (Mercury Surface, Space Environment, Geochemistry, and Ranging) mission to Mercury discovered that irrespective of its formation closest to the Sun, Mercury...
Conference Paper
Full-text available
On October 3rd, 2018 the Haya-busa2 spacecraft [1] delivered the MASCOT lander [2] to the surface of near Earth asteroid (162173) Ryugu, where itoperated for 17hoursand 7 min.Ryugu has a diameter of 850-880 m, a geometric V-band geometric albedo between 0.042 and 0.055, a bond albedo of 0.019±0.003, and is classified as a Cg taxonomic type[3]. Duri...
Conference Paper
The Venus Emissivity Mapper is the first flight instrument designed to focus on mapping the surface of Venus using atmospheric windows around 1 micron. After several years of development, VEM has a mature design with an existing laboratory prototype verifying an achievable instrument SNR of well above 1000, as well as predicted error in retrieval o...
Article
In order to determine the controls on the reflectance spectra of hydrated carbonaceous chondrites, reflectance spectra were measured for a series of samples with well-determined mineralogy, water-content, and thermal history. This includes 5 CR chondrites, 11 CM chondrites, and 7 thermally metamorphosed CM chondrites. These samples were characteriz...
Conference Paper
The MErcury Radiometer and Thermal infrared Imaging Spectrometer (MERTIS) is a highly integrated instrument to study mineralogy and temperature distribution of Mercury’s surface in unprecedented quality. MERTIS was proposed in 2003 as payload of the Mercury Planetary Orbiter spacecraft of the joint ESA-JAXA BepiColombo mission. With the planned lau...
Conference Paper
Full-text available
Small bodies like asteroids and comets are little differentiated objects that have preserved information about the early state of our solar system. Depending on the heliocentric distance of their origin and their further development they exhibit different pristine compositions that include minerals, ices, and refractory organics. Thus, the composit...
Conference Paper
TROTIS (TROjan asteroid Thermal Infrared multi-Spectral imager) is a high spatial-resolution thermal imaging system optimized for targets in the outer solar system with heritage from the Miniaturized Asteroid thermal infrared Imager and Radiometer (MAIR) for the AIDA mission as well as Bepi-Colombo mission’s MErcury Radiometer and Thermal Infrared...
Conference Paper
Spectroscopy is still the most accurate methodology to remotely study the surface composition of celestial bodies (and its evolution). For more than ten years the Planetary Emissivity Laboratory (PEL) of DLR in Berlin has provided spectral measurements of planetary analogues from the visible to the far-infrared range for comparison with remote sens...
Article
This study examines the level of structural uniformity within Mercury's regolith as a function of geomorphological unit. Using two categories of photometric models (Hapke versus Kaasalainen–Shkuratov), the variation between and within similar geomorphological units are examined with the Mercury Atmosphere and Surface Composition Spectrometer (MASCS...
Article
Examination of the Mercury Atmosphere and Surface Composition Spectrometer (MASCS) photometry sequence data sets, and comparison of modeling results using both the Hapke and Kaasalainen–Shkuratov models show that these models can provide an improved photometric standardization to the MASCS's Visible and InfraRed Spectrograph (VIRS) data sets over t...
Conference Paper
The Venusian atmosphere creates inhospitable temperature and pressure conditions for the surface of Venus, Earth's twin planet, making in-situ measurements of any appreciable length difficult, expensive, and risky to obtain. Yet, because of the apparent youthfulness of Venus' surface features, long-duration seismic observations are in high demand i...
Conference Paper
Of all known planets and moons in the galaxy, Venus remains the most Earth-like in terms of size, composition, surface age, and distance from the Sun [1]. Although not currently habitable, Venus lies within the Sun's 'Goldilocks zone', and may have been habitable before Earth [2]. What caused Venus to follow a divergent path to its present hostile...
Article
Thermal Infrared Imager TIR on Hayabusa2 has proven its in-flight performance to detect celestial bodies during the cruise phase, especially by the observations of the Earth and the Moon before and after the Earth swing-by on 3rd of December 2015. The result indicates that the target C-type asteroid 162173 Ryugu will be detected from the distance o...
Article
In order to determine the controls on the reflectance spectra of hydrated carbonaceous chondrites, reflectance spectra were measured for a series of samples with well-determined mineralogy, water-content, and thermal history. This includes 5 CR chondrites, 11 CM chondrites, and 7 thermally metamorphosed CM chondrites. These samples were characteriz...
Conference Paper
Full-text available
The SPS-OKEANOS (Outsized Kitecraft for Exploration and AstroNautics in the Outer Solar system) is under study in Japan to rendezvous with and land on a Jupiter Trojan asteroid [1]. It is primarily an engineering mission to demonstrate advanced space technology but also to conduct key science for understanding the solar system origin and evolution...
Article
Full-text available
New observations from the Venus Express spacecraft as well as theoretical and experimental investigation of Venus analogue materials have advanced our understanding of the petrology of Venus melts and the mineralogy of rocks on the surface. The VIRTIS instrument aboard Venus Express provided a map of the southern hemisphere of Venus at ∼1 μm allowi...
Conference Paper
The Venus Emissivity Mapper (VEM) is the first flight instrument specially designed to map the surface of Venus using the narrow atmospheric windows around 1 micron. VEM is proposed for the European Space Agency's M5/EnVision proposal in combination with a high-resolution radar mapper (see Abstract #1937). Mapping of Venus with VEx/VIRTIS using the...
Conference Paper
Current and upcoming planetary missions deliver a huge amount of different data (remote sensing data, in-situ data, and derived products). Within this contribution present how different data (bases) can be managed and merged, to enable multi-parameterized querying based on the constant spatial context.
Conference Paper
Due to the increasing volume of the returned data from space mission, the human search for correlation and identification of interesting features becomes more and more unfeasible. Statistical extraction of features via machine learning methods will increase the scientific output of remote sensing missions and aid the discovery of yet unknown featur...
Conference Paper
Full-text available
The Planetary Spectroscopy Laboratory (PSL, formerly known as the Planetary Emissivity Laboratory-PEL) of DLR in Berlin is a well established facility providing spectroscopic measurements of planetary analogue materials. Spectral measurements of planetary analogues from the visible to the far-infrared range are routinely measured for comparison wit...
Conference Paper
At the Planetary Spectroscopy Laboratory (PSL) we measured emissivity spectra in vacuum (0.7 mbar) for a large suite of Mercury surface analogue materials in the MERTIS spectral range (7-14 micron) for sample temperatures from 100°C to above 400°C.
Conference Paper
Full-text available
The Venus Emissivity Mapper (VEM) is the first flight instrument specially designed with a sole focus on mapping the surface of Venus using the narrow atmospheric windows around 1μm. VEM will provide a global map of surface composition as well as redox state of the surface, providing a comprehensive picture of surface-atmosphere interaction on Venu...
Article
Full-text available
The thermal infrared imager TIR onboard Hayabusa2 has been developed to investigate thermo-physical properties of C-type, near-Earth asteroid 162173 Ryugu. TIR is one of the remote science instruments on Hayabusa2 designed to understand the nature of a volatile-rich solar system small body, but it also has significant mission objectives to provide...
Article
The VIRTIS instrument on Venus Express observed thermal emission from the surface of Venus at 1 μm wavelength and thus would have detected sufficiently bright incandescent lava flows. No eruptions were detected in the observations between April 2006 and October 2008, covering an area equivalent to 7 times the planets surface on separate days. Model...