Precise Analytical Computation of Frozen-Eccentricity, Low Earth Orbits in a Tesseral Potential

Classical procedures for designing Earth’s mapping missions rely on a preliminary frozen-eccentricity orbit analysis. This initial exploration is based on the use of zonal gravitational models, which are frequently reduced to a simpleJ2-J3analysis. However, theJ2-J3model may not be accurate enough for some applications. Furthermore, lower order truncations of the geopotential are known to fail in describing the behavior of elliptic frozen orbits properly. Inclusion of a higher degree geopotential, which also takes into account the short-period effects of tesseral harmonics, allows for the precise computation of frozen-eccentricity, low Earth orbits that show smaller long-period effects in long-term propagations than those obtained when using the zonal model design.

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Nonsingular recursion formulas for third-body perturbations in mean vectorial elements

Astronomy and Astrophysics ◽

10.1051/0004-6361/201937106 ◽

2020 ◽

Vol 634 ◽

pp. A61

Author(s):

M. Lara ◽

A. J. Rosengren ◽

E. Fantino

Keyword(s):

Arbitrary Order ◽

Keplerian Motion ◽

Third Body ◽

Period Effects ◽

Elliptic Orbits ◽

Short Period ◽

Recursion Formulas ◽

In Series ◽

Mean Elements

The description of the long-term dynamics of highly elliptic orbits under third-body perturbations may require an expansion of the disturbing function in series of the semi-major axes ratio up to higher orders. To avoid dealing with long series in trigonometric functions, we refer the motion to the apsidal frame and efficiently remove the short-period effects of this expansion in vectorial form up to an arbitrary order. We then provide the variation equations of the two fundamental vectors of the Keplerian motion by analogous vectorial recurrences, which are free from singularities and take a compact form useful for the numerical propagation of the flow in mean elements.

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Averaging Tesseral Effects: Closed Form Relegation versus Expansions of Elliptic Motion

Mathematical Problems in Engineering ◽

10.1155/2013/570127 ◽

2013 ◽

Vol 2013 ◽

pp. 1-11 ◽

Cited By ~ 4

Author(s):

Martin Lara ◽

Juan F. San-Juan ◽

Luis M. López-Ochoa

Keyword(s):

Closed Form ◽

Artificial Satellites ◽

Orbit Propagation ◽

Elliptic Motion ◽

Period Effects ◽

Short Period ◽

Orbit Eccentricity ◽

Pros And Cons ◽

Tesseral Harmonics

Longitude-dependent terms of the geopotential cause nonnegligible short-period effects in orbit propagation of artificial satellites. Hence, accurate analytical and semianalytical theories must cope with tesseral harmonics. Modern algorithms for dealing analytically with them allow for closed formrelegation. Nevertheless, current procedures for the relegation of tesseral effects from subsynchronous orbits are unavoidably related to orbit eccentricity, a key fact that is not enough emphasized and constrains application of this technique to small and moderate eccentricities. Comparisons with averaging procedures based on classical expansions of elliptic motion are carried out, and the pros and cons of each approach are discussed.

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Background in low Earth orbits measured by LEGRI telescope – short and long term variability

Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms ◽

10.1016/s0168-583x(99)00403-6 ◽

1999 ◽

Vol 155 (1-2) ◽

pp. 160-168 ◽

Cited By ~ 5

Author(s):

F Sánchez ◽

F Ballesteros ◽

A Robert ◽

M.J Rodriguez-Alvarez ◽

V Reglero ◽

...

Keyword(s):

Short And Long Term ◽

Low Earth Orbits ◽

Earth Orbits

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Opportunities to Intercalibrate Radiometric Sensors from International Space Station

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-13-00163.1 ◽

2014 ◽

Vol 31 (4) ◽

pp. 890-902 ◽

Cited By ~ 6

Author(s):

C. M. Roithmayr ◽

C. Lukashin ◽

P. W. Speth ◽

D. F. Young ◽

B. A. Wielicki ◽

...

Keyword(s):

Solar Radiation ◽

International Space Station ◽

Space Station ◽

Quantitative Investigation ◽

International Space ◽

Study Support ◽

Instruments And Techniques ◽

Low Earth Orbits ◽

Earth Orbits

Abstract Highly accurate measurements of Earth’s thermal infrared and reflected solar radiation are required for detecting and predicting long-term climate change. Consideration is given to the concept of using the International Space Station to test instruments and techniques that would eventually be used on a dedicated mission, such as the Climate Absolute Radiance and Refractivity Observatory (CLARREO). In particular, a quantitative investigation is performed to determine whether it is possible to use measurements obtained with a highly accurate (0.3%, with 95% confidence) reflected solar radiation spectrometer to calibrate similar, less accurate instruments in other low Earth orbits. Estimates of numbers of samples useful for intercalibration are made with the aid of yearlong simulations of orbital motion. Results of this study support the conclusion that the International Space Station orbit is ideally suited for the purpose of intercalibration between spaceborne sensors.

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Atmosphere density changes caused by the motion of spacecrafts in low Earth orbits

Kosmìčna nauka ì tehnologìâ ◽

10.15407/knit2009.01.013 ◽

2009 ◽

Vol 15 (1) ◽

pp. 13-18 ◽

Cited By ~ 6

Author(s):

A.I. Maslova ◽

◽

A.V. Pirozhenko ◽

Keyword(s):

Atmosphere Density ◽

Low Earth Orbits ◽

Earth Orbits

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Effect of polarization on the link dynamics of a spinning low‐earth orbits satellite aligned with geomagnetic field

Engineering Reports ◽

10.1002/eng2.12402 ◽

2021 ◽

Author(s):

Rajavardhan Talashila ◽

Harishankar Ramachandran

Keyword(s):

Geomagnetic Field ◽

Low Earth Orbits ◽

Earth Orbits

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Management of a Mycotic Aneurysm in a Patient with COVID-19: A Case Report

Medicina ◽

10.3390/medicina57060620 ◽

2021 ◽

Vol 57 (6) ◽

pp. 620

Author(s):

Muzammil H. Syed ◽

Mark Wheatcroft ◽

Danny Marcuzzi ◽

Hooman Hennessey ◽

Mohammad Qadura

Keyword(s):

Abdominal Aortic Aneurysm ◽

Aortic Aneurysm ◽

Stent Graft ◽

Mycotic Aneurysm ◽

Neurological Deficits ◽

Endovascular Stent ◽

Endovascular Stents ◽

Abdominal Aortic ◽

Short Period

The aim of this paper is to share our experience in managing a patient with Klebsiella pneumoniae mycotic abdominal aortic aneurysm who was also infected with COVID-19. A 69-year-old male was transferred to our hospital for the management of an infra-renal mycotic abdominal aortic aneurysm. During his hospital course, the patient contracted severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). He was intubated due to respiratory distress. Over a short period, his mycotic aneurysm increased in size from 2.5 cm to 3.9 cm. An emergency repair of his expanding aneurysm was achieved using our previously described protocol of coating endovascular stents with rifampin. The patient was managed with a rifampin-coated endovascular stent graft without any major complications. Postoperatively, the patient did not demonstrate any neurological deficits nor any vascular compromise. He remained afebrile during his postoperative course and was extubated sometime thereafter. He was then transferred to the ward for additional monitoring prior to his discharge to a rehab hospital while being on long-term antibiotics. During his hospital stay, he was monitored with serial ultrasounds to ensure the absence of abscess formation, aortic aneurysm growth or graft endoleak. At 6 weeks after stent graft placement, he underwent a CT scan, which showed a patent stent graft, with a residual sac size of 2.5 cm without any evidence of abscess or endoleak. Over a follow-up period of 180 days, the patient remained asymptomatic while remaining on long-term antibiotics. Thus, in patients whose surgical risk is prohibitive, endovascular stent grafts can be used as a bridge to definitive surgical management.

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An unusually low density ultra-short period super-Earth and three mini-Neptunes around the old star TOI-561

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3728 ◽

2020 ◽

Author(s):

G Lacedelli ◽

L Malavolta ◽

L Borsato ◽

G Piotto ◽

D Nardiello ◽

...

Keyword(s):

Transit Time ◽

Time Variation ◽

Planetary System ◽

Radial Velocities ◽

Low Density ◽

Outer Planets ◽

Short Period ◽

The Stability

Abstract Based on HARPS-N radial velocities (RVs) and TESS photometry, we present a full characterisation of the planetary system orbiting the late G dwarf After the identification of three transiting candidates by TESS, we discovered two additional external planets from RV analysis. RVs cannot confirm the outer TESS transiting candidate, which would also make the system dynamically unstable. We demonstrate that the two transits initially associated with this candidate are instead due to single transits of the two planets discovered using RVs. The four planets orbiting TOI-561 include an ultra-short period (USP) super-Earth (TOI-561 b) with period Pb = 0.45 d, mass Mb = 1.59 ± 0.36 M⊕ and radius Rb = 1.42 ± 0.07 R⊕, and three mini-Neptunes: TOI-561 c, with Pc = 10.78 d, Mc = 5.40 ± 0.98 M⊕, Rc = 2.88 ± 0.09 R⊕; TOI-561 d, with Pd = 25.6 d, Md = 11.9 ± 1.3 M⊕, Rd = 2.53 ± 0.13 R⊕; and TOI-561 e, with Pe = 77.2 d, Me = 16.0 ± 2.3 M⊕, Re = 2.67 ± 0.11 R⊕. Having a density of 3.0 ± 0.8 g cm−3, TOI-561 b is the lowest density USP planet known to date. Our N-body simulations confirm the stability of the system and predict a strong, anti-correlated, long-term transit time variation signal between planets d and e. The unusual density of the inner super-Earth and the dynamical interactions between the outer planets make TOI-561 an interesting follow-up target.

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Heatwaves in Kenya 1987–2016: Facts from CHIRTS High Resolution Satellite Remotely Sensed and Station Blended Temperature Dataset

Atmosphere ◽

10.3390/atmos12010037 ◽

2020 ◽

Vol 12 (1) ◽

pp. 37

Author(s):

Martial Amou ◽

Amatus Gyilbag ◽

Tsedale Demelash ◽

Yinlong Xu

Keyword(s):

High Resolution ◽

Adaptation Strategies ◽

Reference Period ◽

The West ◽

Tana River ◽

Short Period ◽

The World ◽

Northern Side ◽

Data Source

As global temperatures continue to rise unabated, episodes of heat-related catastrophes across the world have intensified. In Kenya, heatwave phenomena and their associated impacts are ignored and neglected due to several reasons, including unreliable and inconsistent weather datasets and heatwave detection metrics. Based on CHIRTS satellite infrared estimates and station blended temperature, this study investigated the spatiotemporal distribution of the heatwave events over Kenya during 1987–2016 using the Heatwave Magnitude Index daily (HWMId). The results showed that contrary to the absence of heatwave records in official national and international disaster database about Kenya, the country experienced heatwaves ranging from less severe (normal) to deadly (super-extreme) between 1987 and 2016. The most affected areas were located in the eastern parts of the country, especially in Garissa and Tana River, and in the west-northern side around the upper side of Turkana county. It was also found that the recent years’ heatwaves were more severe in magnitude, duration, and spatial extent. The highest magnitude of the heatwaves was recorded in 2015 (HWMId = 22.64) while the average over the reference period is around 6. CHIRTS and HWMId were able to reveal and capture most critical heatwave events over the study period. Therefore, they could be used respectively as data source and detection metrics, for heatwaves disaster emergency warning over short period as well as for long-term projection to provide insight for adaptation strategies.

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