Issues Magazine


By By Sally Woollett


An overview of what's in this edition of Issues.

As this edition of Issues goes to press, twin plumes of water vapour are periodically gushing from Ceres. Thanks to the infrared “vision” of the telescope at the Herschel Space Observatory, we have proof that this dwarf planet, between the orbits of Mars and Jupiter, possesses an icy surface and an atmosphere.

A project of the European Space Agency, Herschel was launched into space in 2009. It was decommissioned last year, but there are plenty of up-and-coming astronomical “eyes”. “But in the next 10 years we’ll see true giants: extremely large telescopes (ELTs) working at optical and infrared wavelengths that have light-collecting mirrors 20 metres or more in diameter,” says Helen Sim of CSIRO Astronomy and Space Science and the Australian Astronomical Observatory (p.6).

While the Hubble Space Telescope, observing in the near ultraviolet, visible and near infrared range, has been incredibly useful scientifically, and the stunning images it produces have captured the public imagination, “it will hand over the baton to its space-based successor, the James Webb Space Telescope (working at infrared wavelengths) and the ground-based ELTs,” by around 2020, says Sim.

By necessity, ground-based space observation is a quiet business. For optical telescopes such as the ELTs, towns and cities pollute the night sky with light. Radio telescopes need to be sited away from our many radio-wave sources, so it makes sense that one of the homes of the new Square Kilometre Array will be on a cattle station hundreds of kilometres from Perth, the world’s most geographically isolated city (the other location will be in southern Africa). Initially, “projects will deal mainly with the formation and evolution of galaxies; magnetic fields in galaxies, including our own; understanding the interstellar medium (the space between the stars); and observing transient radio phenomena (including new kinds, it is expected),” explains Sim (p.13).

Light pollution is a significant problem but it doesn’t have to be a permanent one, says Nick Lomb of the Sydney Observatory and the Powerhouse Museum (p.33). “We could keep our cities and towns as bright and exciting places, yet by improving the quality of lighting increase public safety, security and health as well as darkening the night sky,” he writes. Using the right type of lighting and following the principles of good lighting would make an appreciable difference.

Pollution from light and radio waves is not the only thing cluttering up the sky. “Currently approximately 29,000 objects of 10 cm diameter or larger exist in various orbits about the Earth,” says Kerrie Dougherty, Curator of Space Technology at the Powerhouse Museum (p.18). This space junk, or orbital debris, includes inactive satellites, spent launch vehicle upper stages and mission-related debris such as reactor fuel cores from radar satellites. “As the most used and most useful orbits become increasingly cluttered with junk, the risk of a collision between the debris and a functioning satellite, crewed spacecraft or spacewalking astronaut increases,” Dougherty explains.

NASA’s Dawn mission is on its way to Ceres and is expected to arrive in the Northern Hemisphere spring of 2015. The Deep Space Network (DSN) is supporting this mission and many others. “The DSN’s Earth-based communications network is an essential component for controlling a spacecraft’s operating modes, loading and reprogramming the onboard computers, navigating the spacecraft to its destination, and sending scientific data back to Earth. [It] maintains around-the-clock coverage with nearly 50 deep space robotic probes via three large antenna complexes located in Goldstone in California, near Madrid in Spain, and near Canberra,” according to Glen Nagle of CSIRO Astronomy and Space Science and the Canberra Deep Space Communication Complex (p.26).

Another mission on DSN’s books is Voyager 1, which has recently been confirmed to be in interstellar space. But has it left our solar system? As with so many science stories, this is complicated, centring on the measurement of magnetic fields and plasma, and on setting some boundaries. “Informally, of course, ‘solar system’ typically means the planetary neighbourhood around our Sun. Because of this ambiguity, the Voyager team has lately favoured talking about interstellar space, which is specifically the space between each star’s realm of plasma influence,” according to the Jet Propulsion Laboratory in California (p.30).

Space exploration is tinged with the excitement of discovery – perhaps of other life, a possibility explored by astrobiologists. “One of the most important ways to find out whether extraterrestrials exist is to investigate the origin of life on Earth. This is because knowledge about the emergence of life on Earth lets us estimate how probable that emergence was,” says Charley Lineweaver at the Planetary Science Institute, the Australian National University (p.36). And while investigating, we inevitably find out about ourselves along the way.

The puzzle of Voyager 1’s whereabouts was partly solved by a burst of solar activity. This activity, which originates from sunspots, affects the Earth’s weather and climate. So-called space weather “describes conditions in our local space environment, and severe conditions include storms of solar energetic particles, which produce enhanced auroral displays. These events can damage satellite electronics, pose radiation risks for astronauts and raise background radiation levels for crew on polar airline flights,” explains Mike Wheatland of the Sydney Institute for Astronomy at the University of Sydney (p.40).

Accurate weather forecasting, including the prediction and monitoring of extreme events such as bushfires and floods, relies on satellite data. This service is particularly important in Australia, with its long coastline and vast land area. Satellite maps use “not only data on cloud formation, temperature and movement, as measured from geostationary satellites some 36,000 km away, but also measurements from other polar-orbiting satellites 700 km away that can accurately measure cloud heights, wind speeds, wind direction and rainfall,” says Alexander Held of CSIRO Marine and Atmospheric Research (p.43). Satellite data is also invaluable in climate modelling.

Voyager 1 has been travelling since 1977, well beyond the span of public interest. “With the end of the exciting space race we saw an end to public excitement about space, a waning of the public support so critical to the funding of space programs,” says Remco Timmermans, Independent Social Media Advisor for Space and Tourism and Executive Director for the United Nations-declared World Space Week (p.49). Space is a big place but it is still within the reach of social media, which appears to be reviving interest in space travel. Twitter feeds such as #NASASocial and #WakeUpRosetta allow users to follow and create space information.

We will find out next year what the Dawn mission discovers on Ceres and how the public contributes.

Thanks to Helen Sim (CSIRO Astronomy and Space Science, and Australian Astronomical Observatory) for her assistance in sourcing articles for this edition.