Why there is no Landsat imagery available for the Gulf of Carpentaria, northern Australia, in 1974-1977?
I have obtained imagery via USGS Earth Explorer from 1972 through to 2017, but there is a gap in 1974-1977, and I cannot seem to find a reason for this. Theoretically, Landsat 1 MSS (1972-1978) and 2 MSS (1975-1982) were around then, but perhaps they just missed the Gulf?
Between 1974 and 1977 there were intermittent problems with the data recording equipment on the satellite. With limited storage capacity on the tape, delays in transmission were observed.
NASA was also starting to plan future satellites which would not carry onboard data recorders. Data from them would only be available through direct transmission. In the last months of the Whitlam government, the Minister for Science, Clyde Cameron, asked the Australian Science, Technology and Engineering Council (ASTEC) to consider a conceptual proposal to establish Landsat reception facilities in Australia. ASTEC recommended against the proposal.
In 1977 ASTEC was again asked to consider a proposal for establishing Landsat reception facilities in more parts in Australia. This time the proposal was vigorously supported by the mining industry, which guaranteed to buy enough data to make the project work financially. The proposal was accepted and a recommendation forwarded to Cabinet that the Australian Landsat Station (ALS) be built. So due to all these things in some parts of Australia, there were issues, which was resolved later on.
Back in the early days of Landsat, the download and storage of data was not centralized. Local datacenters downlinked the data from the satellites and stored it. While most of the data from those local datacenters has since been centralized, not all data has been brought in - for various reasons. In some cases, the data may be irretrievably lost. In the case of Australia, the local datacenter, run by Geoscience Australia seems to have been late to the party, and didn't properly start downloading data til rather late (1979), so it could be imagined that data is sparse over that area, in an effort to limit the data storage requirements on the satellite (since it would have to store the data, until it could downlink the data to a different station).
The above is generally the reason for strange gaps in the time series of old Landsat data.
