April 2012 Extra: Alternative

In the show this time, Dr Christine Jordan tells about the computers that run the telescope and about the data processing at Jodrell Bank in the JodBite, we talk to Prof. Raman Prinja about stellar winds in massive stars, Dr Paulo Freire discusses testing alternative theories of gravity using pulsars and your astronomical questions are answered by Dr Melanie Gendre.

JodBite with Dr Christine Jordan

Dr Christine Jordan works on the computing side of Jodrell Bank Observatory, managing the control of the telescopes and the processing of their data. Here she talks about the systems she has worked with over the years, from punch-tape computers to the latest multi-processor backend machines, and describes the oldest extant computer at Jodrell Bank. She explains how physical and computational modifications continue to improve the sensitivity, pointing accuracy and observing bandwith of the Lovell Telescope, keeping it at the cutting edge of radio astronomy. She also talks about her interests in knitting and weaving, which have curious similarities to computer programming.

Interview with Prof. Raman Prinja

Prof. Raman Prinja from University College London talks to us about stellar winds in massive stars and how this mechanism spread newly formed chemical elements into the interstellar medium. He also explains how the study of stellar winds gives astronomers information on the evolution of these stars, from birth to death.

Interview with Dr Paulo Freire

Dr Paulo Freire studies pulsars at the Max Planck Institute for Radio Astronomy in Bonn, Germany. Here he explains how he is using precise timing of the radio pulsar PSR J1738+0333 to test alternative theories of gravity whose predictions differ from those of general relativity. This pulsar is particularly special as it has a binary white dwarf companion that can be detected optically. Measurements of the Doppler shift of the white dwarf's spectrum, combined with pulsar timing data, yield precise masses for the two objects. Theories of gravity can then be used to predict the rate at which they will spiral inwards as they orbit one another, and these predictions can be tested against the rate measured through pulsar timing. The observations agree with general relativity so far, and will be used to rule in or out various alternative theories that postulate slightly different behaviour for the force of gravity. As well as making an indirect measurement of the gravitational waves whose emission causes the orbits to shrink, this will help to determine whether theories which 'explain away' dark matter and dark energy could be real.

Ask an Astronomer

Dr Melanie Gendre answers your astronomical questions:

• Terry asks "when does a photon of light stop being a photon? As space time is stretched does it evolve into something else? Is there a photon equivalent in the radio spectrum?"
• Our second question comes from Jodatheoak who asks "What is the Cassini Division?" In her answer, Melanie refers to the Tacoma Bridge.
• The next question is from hmw who asks "What are the legal implications of making a home brew spacecraft - are there any laws regulating space? Is anyone allowed to send out a probe in space?"
• Our final question comes from Graham who asks "I wish to buy a telescope to broaden my horizons and hoped you could recommend some." In her answer, Melanie refers to Ian Morison's guide to buying a telescope.

Odds and Ends

SpaceX is preparing to launch its Dragon capsule (an unmanned capsule) to the ISS on April 30th. This will be the first time a privately funded cargo ship will rendez-vous with the ISS. SpaceX has a contract with NASA to provide 12 Dragon cargo missions, and the only other private company with a similar contract is Orbital Sciences with a contract to do 8 missions where its cargo ships Cygnus docks and supplies the ISS.

The results of the annual star count--organised by the British Astronomical Association's Campaign for Dark Skies (CfDS) and the Campaign to Protect Rural England (CPRE)--are in! But it's bad news for amateur astronomers: over half of the participants were unable to see more than 10 stars in the constellation Orion (in truly dark skies over 30 can be observed!). Campaigners hope new government guidelines on reducing light pollution will help to reverse the trend.

This August NASA's Mars Science Laboratory, Curiosity, will be added to the long list of robotic visitors sent to Mars by humans. However a recent scientific paper by Ian Crawford argues that really it should be us making the 690 day journey to Mars and not our robotic friends. The arguements for this are far more than wide eyed idealism but simply because we can do more, go further and in the long run cost loss.

Show Credits