Aug 30 1974
From The Space Library
Space News for this day. (1MB PDF)
30 August-14 September: NASA launched Ans 1 Netherlands Astronomical Satellite from Western Test Range on a four-stage Scout launch vehicle at 7:08 am PDT (10:08 am EDT) . The satellite entered an elliptical polar orbit with a 1167-km apogee, 254-km perigee, 99.0-min period, and 98.1° inclination-significantly different from the planned circular orbit-because of a malfunction in the 1st stage of the Scout. Changes in the spacecraft program and scientific instrument operations program were made to accommodate to the actual orbit. Although the orbit hindered the observation program, the primary objective-to increase the scientific knowledge of stellar ultraviolet and x-ray sources-could be achieved.
The spacecraft was pointed at the sun, the solar panels were deployed, and fine pointing in a three-axis stabilized condition was established. All three experiments-a hard x-ray experiment provided by the U.S. and a Uv telescope and soft x-ray experiment provided by The Netherlands-were turned on by 8 Sept. In-orbit checkout of experiments and space-craft was completed 13 Sept. and the operational phase of the mission began 14 Sept.
Principal effect of the orbit on the scientific program was the loss of observing time. The higher apogee placed the spacecraft in the Van Allen radiation belts longer than planned, creating a more intense radiation background than anticipated. The UV telescope could operate effectively for 70% of each orbit and observe 10th-magnitude stars only when the spacecraft was below 500 km. Only 5th-magnitude or brighter stars were observable most of the time.
The U.S. x-ray experiment could make effective observations about 25% of the total possible observing time; the experiment could operate below 700 km but not over the poles or the South Atlantic Anomaly. The soft x-ray experiment consisted of a large-area detector, which was operating similarly to the U.S. experiment, and a grazing-incidence telescope, which was seriously affected by the' radiation background. Al-though much of the acquired data was not usable, most future data might be recovered through improved analysis techniques.
Despite the problems, the orbit would provide nine months of full sun-light, rather than the six months expected, permitting reobservations, of objects observed during the first three months. In addition, aerodynamic drag would lower the apogee over a period of time, decreasing the passage time through the Van Allen belts.
Ans 1 was launched under a Memorandum of Understanding signed 5 June 1970 by NASA and the Astronomical Netherlands Satellite Program Authority (ANSPA) . NASA provided the x-ray experiment, spacecraft technical support, the Scout launch vehicle and services, and limited tracking and data acquisition. The Netherlands was responsible for the spacecraft design, fabrication, and testing; two experiments; and primary space-craft command, control, and tracking and data acquisition. Ans 1 was the first satellite to be controlled completely from the European Space Research Organization's operations center at Darmstadt, Germany. The ANS program was managed for NASA by Goddard Space Flight Center under the direction of the Office of Space Science. Langley Research Center had responsibility for the Scout launch vehicle. (NASA MORS, 21 Aug, 6 Nov 74; GSFC SSR, 31 Aug 74; GSFC proj mgr, interview, 15 July 75; ESRO Release, 23 Aug 74)
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