Comparison of the North and South Polar Caps of Mars: New Observations from MOLA Data and Discussion of Some Outstanding Questions

Icarus ◽  
2001 ◽  
Vol 154 (1) ◽  
pp. 145-161 ◽  
Author(s):  
K Fishbaugh
Keyword(s):  
The North ◽  
Polar Caps ◽  
North And South ◽  
South Polar

Water on Mars: The Real Deal

2020 ◽  
pp. 77-88
Author(s):  
David A. Weintraub
Keyword(s):  
Thin Layer ◽  
Lake Ontario ◽  
Significant Evidence ◽  
Melting Snow ◽  
The North ◽  
Polar Caps ◽  
Water On Mars ◽  
North And South ◽  
Recent Epoch ◽  
South Polar

This chapter talks about the astronomers that have solved some of the riddles of how much water Mars had and still has, a century and a half after William Huggins first proved that Mars had water. It highlights that Mars' water was no longer in the liquid state on the surface as the planet had become much dryer after billions of years. It also examines significant evidence that strongly suggests that Mars experienced a more recent epoch when water carved valleys and was formed from melting snow and ice that flowed slowly into and out of chains of lakes. The chapter describes one of Mars' lakes that appears to have been widespread both north and south of the Martian equator, containing more water than Lake Ontario. It discusses Mars' layered ice deposits at the north and south polar caps, in which a thin layer is deposited each Martian winter and then sublimates in Martian spring.

Coverage Analysis of Lunar Communication/Navigation Constellations Based on Halo Orbits and Distant Retrograde Orbits

2020 ◽  
Vol 73 (4) ◽  
pp. 932-952
Author(s):  
Zhao-Yang Gao ◽  
Xi-Yun Hou
Keyword(s):  
Lunar Surface ◽  
Polar Regions ◽  
The Moon ◽  
Halo Orbits ◽  
Satellite Constellation ◽  
The North ◽  
Polar Caps ◽  
Distant Retrograde Orbits ◽  
Distant Retrograde Orbit ◽  
South Polar

AbstractWith more and more missions around the Moon, a communication/navigation constellation around the Moon is necessary. Halo orbits, due to their unique geometry, are extensively studied by researchers for this purpose. A dedicated survey is carried out in this work to analyse the coverage ability of halo orbits. It is found that a two-satellite constellation is enough for continuous one-fold coverage of the north or the south polar regions but never both. A three-satellite constellation is enough for continuous one-fold coverage of both north and south polar regions. A four-satellite constellation can cover nearly 100% of the whole lunar surface. In addition, the coverage ability of another special orbit – distant retrograde orbit (DRO) – is analysed for the first time in this study. It is found that three satellites on DROs can cover 99·8% of the lunar surface, with coverage gaps at polar caps. A four-satellite constellation moving on spatial DROs can cover nearly the whole lunar surface. By combining halo orbits and DROs, we design a five-satellite constellation composed of three halo orbit satellites and two DRO satellites. This constellation can provide 100% continuous one-fold coverage of the whole lunar surface.

scholarly journals Mean Chemical Abundance of the F Stars as a Function of Distance from the Galactic Plane

1977 ◽  
Vol 4 (2) ◽  
pp. 51-52
Author(s):  
A. Blaauw
Keyword(s):  
Galactic Plane ◽  
Photometric System ◽  
Chemical Abundance ◽  
The North ◽  
Polar Caps ◽  
Metal Abundance ◽  
The Mean ◽  
F Stars ◽  
North And South ◽  
European Regional

At the Tbilisi European Regional Meeting 1975, I reported on results of uvby, Hß photometry of F-type stars in the north and south galactic polar caps (Blaauw and Garmany, 1976), based on stars in the McCormick proper motion fields between latitudes 60° and the poles. A relation was shown to exist between the quantity Am. as determined in this photometric system, and the distance, z, from the galactic plane; Δm1. being a measure of the metal abundance in these stars. The spectral range we deal with is defined by b-y = 0.25 to 0.40, corresponding with F0 to G2. It was found that, from the solar neighbourhood near z = 0, to z = 700 pc, the mean relative metal abundance M/H decreases by a factor of about one third.

scholarly journals Asymmetric access of energetic solar protons to the Earth's north and south polar caps

1971 ◽  
Vol 76 (19) ◽  
pp. 4262-4275 ◽  
Author(s):  
J. A. Van Allen ◽  
J. F. Fennell ◽  
N. F. Ness
Keyword(s):  
Polar Caps ◽  
North And South ◽  
South Polar

Preliminary results of the study on the reasons of the Hai Hau erosion phenomenon

2007 ◽  
Vol 29 (3) ◽  
pp. 415-426
Author(s):  
Pham Van Ninh ◽  
Phan Ngoc Vinh ◽  
Nguyen Manh Hung ◽  
Dinh Van Manh
Keyword(s):  
Mathematical Modeling ◽  
Historical Data ◽  
Middle Part ◽  
Red River ◽  
Erosion Process ◽  
Red River Delta ◽  
The North ◽  
Severe Erosion ◽  
North And South ◽  
Very High

Overall the evolution process of the Red River Delta based on the maps and historical data resulted in a fact that before the 20th century all the Nam Dinh coastline was attributed to accumulation. Then started the erosion process at Xuan Thuydistrict and from the period of 1935 - 1965 the most severe erosion was contributed in the stretch from Ha Lan to Hai Trieu, 1965 - 1990 in Hai Chinh - Hai Hoa, 1990 - 2005 in the middle part of Hai Chinh - Hai Thinh (Hai Hau district). The adjoining stretches were suffered from not severe erosion. At the same time, the Ba Lat mouth is advanced to the sea and to the North and South direction by the time with a very high rate.The first task of the mathematical modeling of coastal line evolution of Hai Hau is to evaluate this important historical marked periods e. g. to model the coastal line at the periods before 1900, 1935 - 1965; 1965 - 1990; 1990 - 2005. The tasks is very complicated and time and working labors consuming.In the paper, the primarily results of the above mentioned simulations (as waves, currents, sediments transports and bottom - coastal lines evolution) has been shown. Based on the obtained results, there is a strong correlation between the protrusion magnitude and the southward moving of the erosion areas.

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