Figure 2.10. Schematic diagram of NIMBUS satellite data transfer (Source)
As indicated in the diagram, NIMBUS images were available to anyone with a suitable decoder, and the NASA web page here: NASA source reports the uses to which European meteorological agencies put the data. As with ESSA data, amateurs could also gain access to the images. This photograph from the Baltimore Sun of May 13 1968 shows a Scottish amateur meteorologist’s set up, and the image he has received can be seen on the cylinder (figure 2.11). It’s worth comparing that with the ‘official set up of an APT receiver in figure 2.12.
This NOAA page gives brief details of one of the DAPP satellites, and this excellent history, Cargill Hall, describes the development of the satellites and the military programmes to which they contributed.
A couple of useful journals from ESSA and NOAA give more detail on how the processes worked, as well as give hints about the quality of the images. ESSA World January 1970 and ‘NOAA’ January 1972 ' have articles on the modern [sic] weather forecasting service and the role of the satellite in it. These two magazines have the look and tone of 'in-
The 'Space Command' article describes how a series of commands are sent to a satellite so that it will turn on a transmitter, transmit its data, and then turn the transmitter back off. It also helps explain the administrative structure. The ATS satellites, for example, are owned by NASA, but the data acquisition process is not carried out by them. Instead it is collected by a data acquisition station and relayed to an operations centre run by NOAA (this would have been managed by ESSA prior to NOAA's creation).
Figure 2.15 shows a member of 'Space Command' checking the quality of a satellite image.
Figure 2.15: Checking satellite image quality on receipt. Source: NOAA
The ESSA World article describes how the satellite images then end up with weather forecasters starting from about 06:00 local time. The strips and mosaics of photographs from the LEO satellites are “less than two hours old” by the time they get to the forecasters, although the ATS images are much newer. The interesting feature about the article is how many people are involved in the process of producing a weather forecast, and how satellite imagery was a relatively small part of that process.
Figure 2.16 shows someone from ESSA looking at a satellite image, and gives a good indication of the size of some of the printouts, and their quality.
Another ESSA world edition provides useful information about the role of meteorological forecasters within NASA. The article, published in April 1967 and available here, describes the work of the Spaceflight Meteorology Group (still in operation today: NOAA), which supported any NASA or DoD work involving orbital launches (and with missiles, sub-
"One specialised service just before each launch is the preparation of a weather map for the flight crew to take with them. On the map are shown the meteorological features over which the crew will pass, as well as areas expected to be unfavourable for landing and recovery operations"
This would obviously be more useful in the much shorter Mercury and Gemini missions than the longer Apollo ones. The article also describes the development of orbital photography as an important contribution to ground forecasting, helping to compare measurements taken by conventional forecasting equipment with visual observations. This was particularly true for the Gemini missions, but as will be shown in the section on orbital missions this work continued with Apollo. The article makes one forecast that did come true:
"One expectation for the future is that Weather Bureau men will help select a smooth landing site for the first astronauts returning from a successful voyage to the moon"
This obviously happened, and the involvement of these satellites in weather forecasting for Apollo splashdowns is proudly commemorated in these first day covers for Apollo 8 and 9 (figure 2.17).
Figure 2.14: DMSP fax receivers in the field. Source.
Readers might also want to look at the two USAF seminars given to trainee meteorologists covering cloud types (part 1, part 2) and cyclonic weather patterns (part 1, part 2). The presentations make extensive use of civilian satellites, and give an insight into the contemporary understanding of how satellite data could be used in conjunction with other data. I cover these in more detail in the discussion section.