57 research outputs found
Lunar impact flash results and space surveillance activities at Kryoneri Observatory
We present current and future activities regarding lunar impact flash and NEO
observations and satellite tracking from Kryoneri Observatory. In particular,
we present results from the ESA-funded NELIOTA program, which has been
monitoring the Moon for impact flashes since early 2017. Using the 1.2 m
Kryoneri telescope, which is equipped with two high frame-rate cameras
recording simultaneously in two optical bands, NELIOTA has recorded over 170
validated lunar impact flashes, while another ~90 have been characterized as
suspected. We present statistical results concerning the sizes, the masses and
the appearance frequency of the meteoroids in the vicinity of the Earth, as
well as the temperatures developed during the impacts. Moreover, we present the
capabilities of the Kryoneri telescope as a sensor for satellite tracking and
the future plans regarding the provision of high-quality services for both the
Planetary Defense activities of ESA (S2P/PDO) and the European Union's Space
Surveillance and Tracking programme (EU/SST).Comment: 14 pages, 19 figures. Proceedings of the 2nd NEO and Debris Detection
Conference, Darmstadt, Germany, 24-26 January 202
An automated procedure for the detection of the Yarkovsky effect and results from the ESA NEO Coordination Centre
Context: The measurement of the Yarkovsky effect on near-Earth asteroids
(NEAs) is common practice in orbit determination today, and the number of
detections will increase with the developments of new and more accurate
telescopic surveys. However, the process of finding new detections and
identifying spurious ones is not yet automated, and it often relies on personal
judgment. Aims: We aim to introduce a more automated procedure that can search
for NEA candidates to measure the Yarkovsky effect, and that can identify
spurious detections. Methods: The expected semi-major axis drift on an NEA
caused by the Yarkovsky effect was computed with a Monte Carlo method on a
statistical model of the physical parameters of the asteroid that relies on the
most recent NEA population models and data. The expected drift was used to
select candidates in which the Yarkovsky effect might be detected, according to
the current knowledge of their orbit and the length of their observational arc.
Then, a nongravitational acceleration along the transverse direction was
estimated through orbit determination for each candidate. If the detected
acceleration was statistically significant, we performed a statistical test to
determine whether it was compatible with the Yarkovsky effect model. Finally,
we determined the dependence on an isolated tracklet. Results: Among the known
NEAs, our procedure automatically found 348 detections of the Yarkovsky effect
that were accepted. The results are overall compatible with the predicted trend
with the the inverse of the diameter, and the procedure appears to be efficient
in identifying and rejecting spurious detections. This algorithm is now adopted
by the ESA NEO Coordination Centre to periodically update the catalogue of NEAs
with a measurable Yarkovsky effect, and the results are automatically posted on
the web portal.Comment: Accepted for publication on A&
The BepiColombo Environment Radiation Monitor, BERM
The BepiColombo Environment Radiation Monitor (BERM) on board the European Space Agency's Mercury Planetary Orbiter (MPO), is designed to measure the radiation environment encountered by BepiColombo. The instrument measures electrons with energies from similar to 150 keV to similar to 10 MeV, protons with energies from similar to 1.5 MeV to similar to 100 MeV, and heavy ions with Linear Energy Transfer from 1 to 50 MeV.mg(-1).cm(2). BERM is operated continuously, being responsible for monitoring the radiation levels during all phases of the mission, including the cruise, the planetary flybys of Earth, Venus and Mercury, and the Hermean environment. In this paper, we describe the scientific objectives, instrument design and calibration, and the in-flight scientific performance of BERM. Moreover, we provide the first scientific results obtained by BERM during the BepiColombo flyby of Earth in April 2020, and after the impact of a solar energetic particle event during the cruise phase in May 2021. We also discuss the future plans of the instrument including synergies with other instruments on the BepiColombo and on other missions.Peer reviewe
Galileo In-Situ Dust Measurements in Jupiter's Gossamer Rings
During its late orbital mission at Jupiter the Galileo spacecraft made two
passages through the giant planet's gossamer ring system. The impact-ionization
dust detector on board successfully recorded dust impacts during both ring
passages and provided the first in-situ measurements from a dusty planetary
ring. In all, a few thousand dust impacts were counted with the instrument
accumulators during both ring passages, but only a total of 110 complete data
sets of dust impacts were transmitted to Earth. Detected particle sizes range
from about 0.2 to 5 micron, extending the known size distribution by an order
of magnitude towards smaller particles than previously derived from optical
imaging (Showalter et al. 2008). The grain size distribution increases towards
smaller particles and shows an excess of these tiny motes in the Amalthea
gossamer ring compared to the Thebe ring. The size distribution for the
Amalthea ring derived from our in-situ measurements for the small grains agrees
very well with the one obtained from images for large grains. Our analysis
shows that particles contributing most to the optical cross-section are about 5
micron in radius, in agreement with imaging results. The measurements indicate
a large drop in particle flux immediately interior to Thebe's orbit and some
detected particles seem to be on highly-tilted orbits with inclinations up to
20 deg.Comment: 13 figures, 4 tables, submitted to Icaru
The BepiColombo Environment Radiation Monitor, BERM
The BepiColombo Environment Radiation Monitor (BERM) on board the European Space Agency's Mercury Planetary Orbiter (MPO), is designed to measure the radiation environment encountered by BepiColombo. The instrument measures electrons with energies from similar to 150 keV to similar to 10 MeV, protons with energies from similar to 1.5 MeV to similar to 100 MeV, and heavy ions with Linear Energy Transfer from 1 to 50 MeV.mg(-1).cm(2). BERM is operated continuously, being responsible for monitoring the radiation levels during all phases of the mission, including the cruise, the planetary flybys of Earth, Venus and Mercury, and the Hermean environment. In this paper, we describe the scientific objectives, instrument design and calibration, and the in-flight scientific performance of BERM. Moreover, we provide the first scientific results obtained by BERM during the BepiColombo flyby of Earth in April 2020, and after the impact of a solar energetic particle event during the cruise phase in May 2021. We also discuss the future plans of the instrument including synergies with other instruments on the BepiColombo and on other missions
Genome-Wide Association Study and Functional Characterization Identifies Candidate Genes for Insulin-Stimulated Glucose Uptake
Distinct tissue-specific mechanisms mediate insulin action in fasting and postprandial states. Previous genetic studies have largely focused on insulin resistance in the fasting state, where hepatic insulin action dominates. Here we studied genetic variants influencing insulin levels measured 2 h after a glucose challenge in \u3e55,000 participants from three ancestry groups. We identified ten new loci (P \u3c 5 × 10-8) not previously associated with postchallenge insulin resistance, eight of which were shown to share their genetic architecture with type 2 diabetes in colocalization analyses. We investigated candidate genes at a subset of associated loci in cultured cells and identified nine candidate genes newly implicated in the expression or trafficking of GLUT4, the key glucose transporter in postprandial glucose uptake in muscle and fat. By focusing on postprandial insulin resistance, we highlighted the mechanisms of action at type 2 diabetes loci that are not adequately captured by studies of fasting glycemic traits
BepiColombo Science Investigations During Cruise and Flybys at the Earth, Venus and Mercury
The dual spacecraft mission BepiColombo is the first joint mission between the European Space Agency (ESA) and the Japanese Aerospace Exploration Agency (JAXA) to explore the planet Mercury. BepiColombo was launched from Kourou (French Guiana) on October 20th, 2018, in its packed configuration including two spacecraft, a transfer module, and a sunshield. BepiColombo cruise trajectory is a long journey into the inner heliosphere, and it includes one flyby of the Earth (in April 2020), two of Venus (in October 2020 and August 2021), and six of Mercury (starting from 2021), before orbit insertion in December 2025. A big part of the mission instruments will be fully operational during the mission cruise phase, allowing unprecedented investigation of the different environments that will encounter during the 7-years long cruise. The present paper reviews all the planetary flybys and some interesting cruise configurations. Additional scientific research that will emerge in the coming years is also discussed, including the instruments that can contribute
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