Who Really Made the Payloads

[Response to the September 25 System Design & Test newsletter, “Whither IIR-M? Whither IIF? Whither Delta II?”]

You state that “Boeing decided for reasons of its own not to have the full IIF payload built by ITT, the first GPS satellite for which this is the case, but to handle the work itself, in-house. ITT built part of the IIF payload, but not the critical M Code or L5 portions.” Unfortunately, the statement is untrue and perpetuates one of the many GPS urban legends that armchair GPS experts have proffered over the history of the program.

No single contractor has ever built the entire GPS payload. The recipe Boeing is using today for Block IIF is pretty much the same one their legacy company, Rockwell International, used on Block I and Block II for nearly two decades on 40 satellites. On Block IIR and IIRM, IIT built more of the boxes and components — but not the whole payload — which includes the atomic frequency standards, signal plumbing, and antennas. This table shows who built what payload component over the years, in an attempt to put this issue to bed and dispel the myth.

Note: Block 1A is what the Joint Program Office called those Block I satellites that included the Integrated Operational Nuclear Detonation (NUDET) Detection System (IONDS).

— Rick Reaser

RICK REASER was assigned to the Navstar Global Positioning System (GPS) Joint Program Office (JPO) as an Air Force officer from 1978–1983, 1996–1997, and 2000–2006. In his 12 years inside the JPO, he served as a Satellite Test Director, Satellite Division Chief, Chief Engineer (twice) and finally as Deputy System Program Director.

Sunspots Declining, May Vanish

[Response to October 1 Survey & Construction e-newsletter, “Solar Activity: Is There Aspirin for This GNSS Headache?”

Solar Cycle 24 has not lived up to any of its advance billing. In fact, so far, it’s been quite a dud. A maximum in 2011 is now virtually impossible, and one in 2012 is unlikely. The 11-year solar cycle usually comprises four years of rise time to maximum and seven years of fall time to minimum. Solar Cycle 23 maximum was in 2000. It has already been eight years of fall time, and Solar Cycle 24 has so far been anemic at best.

There is active discussion across the blogosphere about Solar Cycles 23 and 24 and possible implications. The official NOAA/NASA panel predictions are expected to be “updated annually.” In conjunction with a Space Weather Workshop in May, the panel simply reiterated its predictions, there being insufficient data on which to base a significant change. The lack of Cycle 24 activity continues to outpace official predictions, and so far, even low-side forecasters seem to have overestimated Cycle 24.

IPS, the Australian Space Weather Agency, recently acknowledged the lack of activity and pushed their forecast another six months down the road.

Jan Janssens maintains a table which contains most of the published predictions. This table has not been updated in the past 12 months, as Solar Cycle 24 continues to behave unexpectedly, and forecasters have little or no additional insight on which to base new predictions.

You’ll see in the table reasons that Solar Cycle 24 will be small, because of the loss of energy through intense solar flares during the declining phase of Cycle 23. An experienced solar forecasters, Ken Schatten, has been wondering if the energy lost to the solar wind through low-latitude coronal holes — which are unusual at solar minimum — has left the sun with too little energy to produce more energetic spots.

Finally, an unpublished paper (available on the web) by Livingston and Penn of the Kitt Peak Observatory notes the trend of decreased contrast between sunspots and the sun, and that if the trend continues, sunspots would vanish entirely by 2015.

— John Sumption, Centennial, Colorado