A comprehensive statistical study of cloud base height using ceilometer over western India

A comprehensive statistical analysis of the cloud base height (CBH) measured by ground-based Vaisala ceilometer (CL31) has been performed to study different layers of the cloud in the lower troposphere up to 7.5?km height over Ahmedabad, western India during 2014 and 2015. The total observations (～69%) of cloud by using ceilometer show annual cloud occurrence frequency of around 64%. Seasonal variation of CBH and cloud occurrence frequency reveal that the maximum/minimum cloud cover is found during southwest (SW) Indian summer monsoon/pre-monsoon season. Three CBHs (CBH1, CBH2, and CBH3) are presented in monsoon period due to high cloud occurrence, and two CBHs (CBH1 and CBH2) are observed in other seasons due to low cloud occurrence by ceilometer over the observational site. The CBH1 (～100–2000?m) and CBH2 (500–3000?m) are observed during SW monsoon and summer season, respectively. The CBH3 is occurred usually in SW monsoon season. Moreover, the cloud cover during the day and night time shows that the occurrence of cloud is more frequent in daytime than nighttime during pre-monsoon and post-monsoon season. The statistical analysis of cloud with ground-based observations is also performed in this study that may be useful for the development/improvement of regional weather and climate models to reduce the uncertainty in the prediction.     

An international symbol for the sustained exploration of space

As humanity prepares to extend its reach beyond low-Earth-orbit for the first time since the 1970s, a new symbol of international cooperation is needed to further promote the message of peace and collaboration such exploration entails. The space race that occurred between the USSR and the USA is an ill-suited model for long-term sustained space exploration because it is too costly and too resource-intensive for a single nation to bear. While competition is healthy for technology development, the success of a sustained space exploration strategy lies beyond technological capabilities. It lies in international cooperation, space policy, and public support. Without these, no program can realistically achieve a sustained presence in space beyond low-Earth orbit. To this effect, this paper proposes a cost-effective first step in the form of a universal symbol which, when placed alongside national flags displayed on hardware and astronaut/cosmonaut/taikonaut flight-suits, would send a strong message to the world that space exploration is done for the benefit of humanity as a whole, not just for spacefaring nations. The “Blue Marble”, the first complete picture of Earth taken from space by humans in 1972, fits this universally appealing symbol. This symbol requires no political collaboration between countries, yet is an image that anyone, anywhere in the world, can relate to regardless of nationality, ethnic origin or religious beliefs. Placed on the shoulder pads of human ’nauts – ambassadors of planet Earth – or prominently displayed on spacebound hardware, this symbol would send a universal message to present and future generations that, in space, our planet is working together for the benefit of everyone.     

Correction to: Mission to Planet Earth: The First Two Billion Years

Space Science Reviews - The Ionospheric Connection Explorer (ICON) mission makes measurements in near-Earth space that provide knowledge of the state of the ionosphere. From the vantage of...     

The benefits and harm of transmitting into space

Deliberate and unintentional radio transmissions from Earth propagate into space. These transmissions could be detected by extraterrestrial watchers over interstellar distances. This article analyzes the harm and benefits of deliberate and unintentional transmissions relevant to Earth and humanity. Comparing the magnitude of deliberate radio broadcasts intended for messaging to extraterrestrial intelligence (METI) with the background radio spectrum of Earth, we find that METI attempts to date have much lower detectability than emissions from current radio communication technologies on Earth. METI broadcasts are usually transient and several orders of magnitude less powerful than other terrestrial sources, such as astronomical and military radars, which provide the strongest detectable signals. The benefits of radio communication on Earth most probably outweigh the potential harm of detection by extraterrestrial watchers; however, the uncertainty regarding the outcome of contact with extraterrestrial beings creates difficulty in assessing whether or not to engage in long-term and large-scale METI.     

Use the water: In-situ resource technology for icy-surface landers

Robotic landers serve vital reconnaissance roles in the exploration of planetary surfaces, but are constrained by deliverable payload size and environment survivability. Although the Mars exploration rovers (MER) have shown incredible survivability, their solar power source limits the science output per sol. Future landers will be larger, and will incorporate more sophisticated data-collection and analysis packages, which will likely bring with them an increased demand for power. Anticipating this demand, we propose an innovative hybrid power system combining a primary radioisotope thermoelectric generator (RTG) with a secondary alkaline fuel cell. This combination provides the opportunity to utilize more effectively the energy produced by the RTG, to produce and store O₂ and H₂ via electrolysis of melted ice, and use this obtained O₂ and H₂ in a variety of ways, including as fuel for a regenerative fuel cell. This hybrid system has applications ranging from planetary rovers and deep-space probes to human habitats.     

A comprehensive study on middle atmospheric thermal structure over a tropic and sub-tropic stations

The general characteristics of middle atmospheric thermal structure have been studied by making use of the Rayleigh lidar data collected over the period of about four years (1998–2001). Here, the data has been used from two different stations in the Indian sub-continent in tropics (Gadanki; 13.5°N, 79.2°E) and in sub-tropics (Mt. Abu; 24.5°N, 72.7°E). The observed monthly mean temperature profiles are compared with different model atmospheres (CIRA-86 and MSISE-90). We observed, the mean temperature profiles have closer agreement with MSISE-90 than CIRA-86. The temperature profiles measured by lidar and HALOE satellite overpass nearby lidar site are generally in agreement with each other. The systematic and statistical errors in deriving temperature are found to be uniform for both the stations, as 1 K at 50 km, 3 K at 60 km and 10 K at 70 km. The special features of mesospheric temperature inversion (MTI) and double stratopause structure (DBS) are also addressed for both the stations.