For novel ideas about building embedded systems (both hardware and firmware), join the 27,000+ engineers who subscribe to The Embedded Muse, a free biweekly newsletter. The Muse has no hype and no vendor PR. It takes just a few seconds (just enter your email, which is shared with absolutely no one) to subscribe.
By Jack Ganssle
A Half Century of TIROS
Summary: TIROS 1, the first weather satellite, was launched 50 years ago.
This week marks the 50th anniversary of the first launch of a TIROS satellite. On April 1, 1960, just two years after the US managed to put our first satellite (Explorer 1) into orbit, TIROS 1 rocketed into orbit. It was a 270 pound spacecraft equipped with twin TV cameras. Placed into a 430 mile-high nearly circular orbit with 48 degree inclination, it could - and did - image great swaths of the globe.
I haven't been able to find much about the electronics technology aboard TIROS 1, but it did use 500 scan-line, 1.27 cm vidicon cameras. That data went to tape, which could store a mere 32 frames. When over a ground station that data was downlinked in 100 seconds by a 235 MHz transmitter. at a power of only two watts. Obviously, the ground antenna was massive and the distance not that far, but it's still impressive. (Consider, though, Pioneer 10 whose last detected transmission was at a range of 7.5 billion miles, via only an 8 watt transmitter).
TIROS 1 failed after 78 days, 15 days earlier than planned, but it spawned a large line of successors. NOAA-19, launched in February of last year, is the most recent.
The mission of TIROS 1 was to take pictures of clouds. It was the first of many weather satellites. How this changed the world! Prior to April 1, 1960 forecasters had very little information about conditions at sea or in remote areas. Hurricanes could only be detected after crossing land, or when the chance ship ran into one (to their great dismay). With satellite imagery the veil was lifted. I wonder how many lives this technology has saved in the last half century?
That very first TIROS was produced by RCA (later GE) in Hightstown, NJ. They built many in the series. My dad worked there in the 70s as a mechanical engineer, and helped design the TIROS N spacecraft. I remember him complaining about the customer's requirement to put a search-and-rescue package aboard (weight is always a problem for space missions). In 1992 when I was sailing alone from England to the US (http://www.ganssle.com/jack/ostar1.html ) I had to activate an EPRIB emergency beacon, which beamed my cry for help via that package to authorities ashore. Four hours later a Canadian Navy P3 Orion was overhead calling me by name. Over 27,000 people have been rescued by the SARSAT program.
Today, our human space missions are in disarray. But the robotic probes continue to return fantastic data, a testament to the engineers who designed them and the public who writes the checks.
Happy birthday, TIROS!
Published March 2, 2010