GPS World, August 2015

The four MMS spacecraft host the highest ever operational GPS receivers in space artists rendition credit NASA September Marks Start of Magnetosphere Mission but Navigators Already Perform A NASA mission to explore magnetic reconnection also made GPS history this spring The Magnetospheric Multiscale MMS mission led by NASAs Goddard Space Flight Center in Greenbelt Md is flying four identically equipped spacecraft in a tight formation to take measurements 100 times faster than any previous space mission Each of the four spinning MMS spacecraft roughly the size of a ballpark once eight booms deploy is equipped with 25 sensors and other components provided by more than 40 partner institutions in the U S Europe and Japan One key component is a GPS receiver dubbed Navigator Magnetic reconnection is a fundamental yet poorly understood process While reconnection occurs throughout the universe when magnetic field lines within plasma connect and disconnect it can impact our technological society since it drives virtually all space weather events that can disrupt low Earthorbiting spacecraft and lead to GPS communications and power blackouts on Earth During the missions first phase which begins in September the spacecraft will travel through reconnection sites on the sun side of Earth where the orbit extends out toward the sun to around 47500 miles One year later ground controllers will move the spacecraft to Earths nightside or magnetotail where the magnetic fields also reconnect an orbit that extends away from Earth to almost 99000 miles nearly halfway to the moon However science operations cant begin before the four move into a highly elliptical orbit and assume their pyramid shape formation that places the spinning spacecraft just 62 miles apart It required a breakthrough to accomplish such an exacting formation and the Goddard developed Navigator GPS provided the solution Begun in the early 2000s as an enabling technology for MMS type missions the Navigator receiver and associated algorithms can quickly acquire and track GPS radiowaves even in weak signal areas well above GPSs 30 plus satellite constellation positioned about 12550 miles above Earth In addition to continuously tracking weak signals the Navigator also must operate as the spacecraft spin at three revolutions per minute As a result each MMS satellite is equipped with two Navigator receivers primary and redundant with four antennas placed around the perimeter of each COPYRIGHT 2015 NORTH COAST MEDIA LLC All rights reserved No part of this publication may be reproduced or transmitted in any form by any means electronic or mechanical including by photocopy recording or information storage and retrieval without permission in writing from the publisher Authorization to photocopy items for internal or personal use or the internal or personal use of specific clients is granted by North Coast Media LLC for libraries and other users registered with the Copyright Clearance Center 222 Rosewood Dr Danvers MA 01923 phone 978 750 8400 fax 978 750 4470 Call for copying beyond that permitted by Sections 107 or 108 of the U S Copyright Law PRIVACY NOTICE North Coast Media LLC provides certain customer contact data such as customers names addresses phone numbers and email addresses to third parties who wish to promote relevant products services and other opportunities which may be of interest to you If you do not want North Coast Media LLC to make your contact information available to third parties for marketing purposes simply call 847 763 4942 between the hours of 8 30 am and 5 pm CT and a customer service representative will assist you in removing your name from North Coast Media LLCs lists GPS WORLD ISSN 1048 5104 is published monthly by North Coast Media LLC IMG Center 1360 East 9th Street Suite 1070 Cleveland OH 44114 SUBSCRIPTION RATES One year 80 two years 129 U S and possessions one year 96 two years 151 Canada and Mexico and one year 155 two years 255 all other countries International pricing includes air expedited service Single copies prepaid only 7 in the United States 9 all other countries Back issues if available are 19 in the U S and possessions 23 all other countries Include 650 per order plus 2 per additional copy for U S postage and handling Periodicals postage paid at Cleveland OH 44101 9603 and additional mailing offices POSTMASTER Please send address change to GPS World PO Box 2090 Skokie IL 60076 Printed in the U S A GPS World August 2015 www gpsworld com 50