Navigation using pulsars ASTRONOMY AND SPACE SCIENCE George Hobbs Nov 2014

Message on Pioneer 10, 11 and Voyager space probes Presentation title | Presenter name | Page 2 Picture credits: wikipedia

Presentation title | Presenter name | Page 3 Sound files from the Parkes and Jodrell Bank Observatories

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The Crab Supernova Presentation title | Presenter name | Page 6

CSIRO. Gravitational wave detection An ancient Chinese Astronomer in AD1054

CSIRO. Gravitational wave detection So what happened?

Presentation title | Presenter name | Page 9  Michael Kramer, MPiFR

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Pulsar Properties Diameter ~ km Mass ~ 1.4 solar masses Density ~ kg.m -3 Thimbleful has a mass of 10 9 tonnes Rotates once to several hundred times per second Acceleration due to gravity at surface of pulsar is ~ m.s -2 (cf 10 m.s -2 at Earth’s surface). Magnetic field of ~ 10 8 T (Sun ~ T) Approx 2,000 known pulsars. CSIRO: | Robert Hollow | Animation: M. Kramer

Why we study pulsars CSIRO. Gravitational wave detection

Change of topic --- the Global positioning system (GPS) 1.Everyone uses GPS (aircraft, cars, military, mapping, …) 2.Problems: a. GPS can be jammed, b. can be switched off 3.“GPS is now such a significant part of our lives that the effects of failure would be catastrophic … affect all emergency services, all systems of traffic control …we would not be able to stock our shops and feed ourselves..” – “On the Map” Simon Garfield. 4.Cannot be used for deep-space navigation Presentation title | Presenter name | Page 13

Pulsar navigation 1.Plaque on Pioneer spacecraft: relative position of the Sun to the center of the galaxy and 14 pulsars! 2.Demonstrates basic idea: the pulsars are a galactic-scale GPS! Presentation title | Presenter name | Page 14 wikipedia

The basic idea Presentation title | Presenter name | Page 15 Individual images: Rosetta (courtesy of ESA), starship Enterprise from the TV series Star Trek. Compilation by MPE.

Example: where is the Parkes telescope? Unpublished work by G. Hobbs and X. You 1.Assume that we’re on the Earth’s surface 2.Use Parkes timing observations and fit for position of Parkes Presentation title | Presenter name | Page 16

Proof of concept – where is Parkes? Unpublished work by G. Hobbs and X. You 1.Assume that we’re on the Earth’s surface 2.Use pulsars observations and fit for position of Parkes Presentation title | Presenter name | Page 17

Proof of concept – where is Parkes? Unpublished work by G. Hobbs and X. You 1.Assume that we’re on the Earth’s surface 2.Use Parkes timing observations and fit for position of Parkes Presentation title | Presenter name | Page 18 Use millisecond pulsar (PSR J ) Correct position to within a few kilometers

Can navigate spacecraft: Earth to Mars trajectory (recent paper by Deng et al. 2013) 1.Can’t fit the Parkes telescope on top of your car! => try smaller telescope => X-ray telescopes! 2.Can we use millisecond pulsar observations to determine the position and velocity of a spacecraft travelling from Earth to Mars? 3.Use software to simulate trajectory – accounts for gravitational field, Solar pressure etc. 4.Assume large ground-based radio telescope to get pulsar timing model before launch 5.Assume XTE-type X-ray telescope on- board the spacecraft Presentation title | Presenter name | Page 19 training.org/images/AGI_STK.jp g

Two algorithms studied 1.Algorithm 1: assumes no prior knowledge of the space-craft trajectory 2.Algorithm 2: makes use of a dynamics model for the space-craft motion 3.Result: position estimation better than 10km 4.Result: velocity estimation better than 1m/s Presentation title | Presenter name | Page 20

Will pulsar navigation really work? 1.Technique will work for interplanetary spacecraft 2.USA, China, Europe and Australia working of techniques and implementation 3.Personally not sure about terrestrial or Earth-orbit navigation using pulsars (need a very sensitive detector) – we’re thinking about it! 4.One day we may leave our solar system and navigate to other stars using pulsars! Presentation title | Presenter name | Page 21

Will pulsar navigation really work? 1.Technique will work for interplanetary spacecraft 2.USA, China, Europe and Australia working of techniques and implementation 3.Personally not sure about terrestrial or Earth-orbit navigation using pulsars (need a very sensitive detector) – we’re working on it! 4.One day we may leave our solar system and navigate to other stars using pulsars! 5.… but I do hope that the GPS is working on my flight back home! Presentation title | Presenter name | Page 22

Thank you CSIRO Astronomy and Space Science George Hobbs Research Scientist t w hobbs CSIRO ASTRONOMY AND SPACE SCIENCE