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19 November 2024 | Story Pat Lamusse | Photo Supplied
Space and satellites 2024
During the visit to the Naval Hill Planetarium, were from the left, Dr Mart-Mari Duvenhage and Prof Matie Hoffman from the UFS Department of Physics, Consul General Stephanie Bunce and Vanessa Toscano from the US Consulate, and Dinah Mangope from the Department of Physics.

A delegation from the United States (US) Consulate General in Johannesburg, including Consul General Stephanie Bunce and Public Affairs Officer, Vanessa Toscano, visited the Bloemfontein Campus of the University of the Free State (UFS). Consul General Bunce met with the acting Vice-Chancellor and Principal of the UFS, Prof Anthea Rhoda, and the Dean of the Faculty of Natural and Agricultural Sciences, Prof Paul Oberholster. The US delegation also visited the Naval Hill Planetarium.

The UFS recently received a grant from the US Embassy to fund a project to promote science education by highlighting the role of satellites in our lives. Colleagues from the Department of Physics had the opportunity to demonstrate first-hand how the planetarium technology will be used to implement the project, which poses the question – what if something happens in space that interferes with the thousands of satellites we use for communication, weather prediction, navigation, banking … surveillance?

Thanks to this grant, the UFS will explore these questions and contribute to space situational awareness (SSA) and space domain awareness (SDA). SSA involves knowledge about the orbits of spacecraft and space debris. SDA refers to the knowledge and understanding of all activities occurring within the space domain.

There are currently at least 10 000 active satellites in Earth orbit, most of which are in low Earth orbit (LEO). However, in addition to satellites, there are well over 45 000 objects larger than 10 cm in orbit, including more than 35 000 pieces of space debris, such as dead satellites, rocket bodies, and pieces from breakups and collisions. Since 1991, there have been at least six unintentional collisions between active satellites and space debris.

Space turned out to be not as big as once thought, especially not in low Earth orbit (LEO – altitude less than 2 000 km). To make things worse, there are plans to launch up to 100 000 new satellites into LEO over the next decade.

Prof Matie Hoffman from the UFS Department of Physics notes, “We live in an era when the space economy is growing fast and the number of objects in Earth orbit, including satellites and space debris, is increasing rapidly. This poses risks to operational satellites. Recent publicity around Elon Musk’s Starlink satellites has generated additional interest around this topic. It is important to raise awareness of the challenges, which will allow scientists to mitigate them.”

The project will involve expertise in optical satellite observations from the University of Michigan through Prof Patrick Seitzer, international patron of the Friends of Boyden Observatory, and the American Museum of Natural History (AMNH). The grant will fund planetarium upgrades that will enable education on space and satellites, as well as optical satellite observations from Boyden Observatory. Beneficiaries will include learners, higher education institutions (both locally and in the US), and the public. South African project partners will be the South African National Space Agency (SANSA), the Future African Space Explorers’ STEM Academy (FASESA), and satellite-related companies in South Africa.

The Boyden Observatory is ideally situated to provide valuable optical satellite observations in an area of the sky that is not accessible from existing satellite observing facilities, especially for objects in LEO. In fact, the first observation of space debris in geosynchronous orbit was from Boyden Observatory in 1967.

The project will be rolled out from the end of 2024, harnessing facilities at both Boyden Observatory and the Naval Hill Planetarium.

News Archive

Well-established root system important for sustainable production in semi-arid grasslands
2015-02-24

Plot layout where production and root studies were done
Photo: Supplied

The importance of a well-established root system for sustainable production in the semi-arid grasslands cannot be over-emphasised.

A study of Prof Hennie Snyman from the Department of Animal and Wildlife and Grassland Sciences at the University of the Free State is of the few studies in which soil-water instead of rainfall has been used to estimate above- and below-ground production of semi-arid grasslands. “In the past, plant ecological studies have concentrated largely on above-ground parts of the grassland ecosystem with less emphasis on root growth. This study is, therefore, one of the few done on root dynamics in drier areas,” said Prof Snyman.

The longevity of grass seeds in the soil seed bank is another aspect that is being investigated at present. This information could provide guidelines in grassland restoration.

“Understanding changes in the hydrological characteristics of grassland ecosystems with degradation is essential when making grassland management decisions in arid and semi-arid areas to ensure sustainable animal production. The impact of grassland degradation on productivity, root production, root/shoot ratios, and water-use efficiency has been quantified for the semi-arid grasslands over the last 35 years. Because of the great impact of sustainable management guidelines on land users, this study will be continuing for many years,” said Prof Snyman.

Water-use efficiency (WUE) is defined as the quantity of above- and/or below-ground plant produced over a given period of time per unit of water evapotranspired. Sampling is done from grassland artificially maintained in three different grassland conditions: good, moderate, and poor.

As much as 86, 89 and 94% of the roots for grasslands in good, moderate and poor conditions respectively occur at a depth of less than 300 mm. Root mass is strongly seasonal with the most active growth taking place during March and April. Root mass appears to be greater than above-ground production for these semi-arid areas, with an increase in roots in relation to above-ground production with grassland degradation. The mean monthly root/shoot ratios for grasslands in good, moderate, and poor conditions are 1.16, 1.11, and 1.37 respectively. Grassland degradation lowered above- and below-ground plant production significantly as well as water-use efficiency. The mean WUE (root production included) was 4.79, 3.54 and 2.47 kg ha -1 mm -1 for grasslands in good, moderate, and poor conditions respectively.

These water-use efficiency observations are among the few that also include root production in their calculations.

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