Three Balloon Satellites Visible From N.Z.

Press, Volume CIII, Issue 30338, 14 January 1964, Page 7

Three Balloon Satellites Visible From N.Z.

At the moment there are three balloon satellites in orbit and all are visible from New Zealand. Another, the long-awaited Echo 2, is due to join them within the next few weeks.

The most easily-visible balloon satellite, until Echo 2 comes on the scene, is the famous Echo 1, which started life as a communications reflector satellite and is now America’s best known and most regular space advertisement. Its orbit is at present in continuous sunlight (it does not pass into the earth’s shadow) and Echo 1 may be seen at two hourly intervals throughout the night. Tonight it will pass almost directly overhead as it travels from west to east at 9.29 p.m. and

again at 11.32 p.m. Being in continuous sunlight it will be visible from horizon to horizon. Again at 1.34 a.m. it will be seen travelling just north of overhead in a north of east direction and finally, at 3.34 a.m., it will pass across the north-western sky, heading just east of north.

The following evening it will follow almost the same apparent paths, but will be seen almost exactly an hour earlier on each pass, except that the earliest pass may be too difficult to see in the evening twilight. The 12 foot-diameter Polkadot balloon, Explorer 9, may be glimpsed in the evening sky tonight at 9.44 p.m., but shortly after rising to the west of north it will disappear into the earth’s shadow. The following evening it will follow a similar path, rising at 9.33 p.m. and will travel a little further before disappearing. On Thursday evening it will pass across the northern sky at an elevation of about 25 degrees above the horizon. At magnitude plus-2 it will appear moderately bright but not as bright as Echo 1. Also it will move very much more rapidly. •The second Polka-dot balloon, Explorer 19, launched last month, is barely visible in the evening sky as it passes from south to north at a height of 1400 miles. In a few months’ time when the perigee of its obit is better placed, it will pass over at a height of about 400 miles and be much easier to see. Tomorrow evening it will pass fairly high across the western sky at 9.16 p.m., but at magnitude +6 it will be very faint and difficult to see. Tonight, at 10.6 p.m., it will be lower and even harder to see. When these balloons are joined by Echo 2, sightings will be much more spectacular. Echo 2 should, at magnitude —2, appear brighter than Sirius, or roughly comparable with the brilliance of Jupiter.