ARLA/CLUSTER: CubeSat para explorar a Anomalia Magnética do Atlântico Sul

[João Gonçalves Costa]

A Anomalia Magnética do Atlântico Sul, AMAS ou SAA (do inglês, South Atlantic Anomaly) é uma região onde a parte mais interna do cinturão de Van Allen tem a máxima aproximação com a superfície da Terra. O resultado é que para uma dada altitude, a intensidade de radiação é mais alta nesta região do que em qualquer outra no planeta. A AMAS é produzida por um "mergulho" no campo magnético terrestre nesta região, causada pelo facto de que o centro do campo magnético terrestre esta deslocado em relação ao centro geográfico por 450 km.

A anomalia do Atlântico Sul afeta satélites e outras naves com órbitas a algumas centenas de quilômetros de altitude e com inclinações orbitais entre 35° e 60°. Nessas órbitas, os satélites que passam periodicamente pela AMAS, ficam expostos durante vários minutos às fortes radiações que ali existem. A International Space Station, orbitando com uma inclinação de 51,6 °, necessitou de um revestimento especial para lidar com o problema. O Hubble Space Telescope não faz observações enquanto está passando pela região.

A AMAS sofre um deslocamento para a direção oeste, cuja velocidade de deslocamento é de 0,3 ° por ano. A taxa de deslocamento é muito próxima da rotação diferencial entre o núcleo da Terra e sua superfície, estimada estar entre 0,3 ° e 0,5 ° por ano.

Fonte: Wikipedia


DynaCube to explore the South Atlantic Anomaly

SA AMSAT report that after launch, DynaCube, a one-unit CubeSat being constructed by Interns at the Denel Dynamics Engineering Academy, will be exploring the South 
Atlantic Anomaly during orbits over the area. 

It is hoped the Cubesat will launch in late 2013 or 2104. The Southern African Amateur Radio Satellite Association (SA AMSAT) say the cost of a launch for this 1U CubeSat could be as high as 1,300,000 Rand (£92,000 or $140,000).

The South Atlantic Anomaly (SAA), off the coast of Brazil, is an area where the Earth's inner Van Allen radiation belt comes closest to the Earth's surface dipping down to an altitude of 200km This leads to an increased flux of energetic particles in this region and exposes orbiting satellites to higher than usual levels of radiation. The effect is caused by the non-concentricity of the Earth and its magnetic dipole. 

The South Atlantic Anomaly is of great significance to satellites and other spacecraft that orbit the Earth at several hundred kilometres altitude; these orbits take satellites through the anomaly periodically, exposing them to several minutes of strong radiation, caused by the trapped protons in the inner Van Allen belt.

The team, all engineers who graduated from various universities in South Africa, spent last year working on the project to gain practical experience before they are assigned to various departments in the company. The Interns were tasked with designing, manufacturing and commissioning a 1U Cube Satellite and its associated ground support systems.

All systems have been tested and are now ready for integration. Although the Interns have come to the end of their year and will start their careers in various departments of Denel Dynamics, they are dedicated to completing the project in their free time. Currently three of the group have obtained their amateur radio license.

DynaCube will operate on Amateur Radio frequencies which were coordinated by the IARU Amateur Satellite Advisory Panel with a downlink of 145.980 MHz, an uplink on 435.050 MHz and a tracking beacon on 145.840 MHz.

Read the full SA AMSAT story and listen to an interview with members of the DynaCube Team at
http://www.amsatsa.org.za/DynaCube.htm

Southern African Amateur Radio Satellite association (SA AMSAT) 
http://www.amsatsa.org.za/