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On this day in (engineering) history…

Stephen Phillips

November 28, 2023

Mariner 4 blasts off from Cape Canaveral, Florida, bound for Mars

It is a fine winter morning at Launch Complex 12 on Cape Canaveral, Florida. Perhaps it is too cold for NASA’s mission controllers to sweat, while they nervously wait for the two-stage rocket sitting on the pad to lift off. 

Today is November 28th, 1964, the vehicle is carrying Mariner 4, and at 9:22AM local time, the engines will ignite and (hopefully) send the space craft on its 228 day voyage to Mars.

Up to now, there have been six failed attempts to send a probe to Mars, five by the USSR and Nasa’s failed Mariner 3. Mariner 4 now carries the hopes of everyone in the space agency. 

Mariner 3 made it to earth orbit only for a metal fairing to jam not jettison. The probe drifted uselessly into space, inert.  Mariner 4 fared better when it’s fairing opened for the probe to begin its mission. After an auspicious start, the objective was a flyby planned for July 14 1965.

The probe itself was powered by four solar panels, mounted in a cross formation around the eight-sided frame carrying the probe’s equipment. Mariner was armed with seven scientific instruments.

  • Imaging system
  • Ionization Chamber
  • Helium magnetometer
  • Plasma probe
  • Cosmic-ray telescope
  • Cosmic ray detector
  • Cosmic dust detector

The instruments were to look for signs that Mars had a magnetic field; to measure particle radiation; mass and mass distribution; charged particles and the movement of protons flowing from the Sun. A television camera would take the first photographs of a planet taken near a planet’s vicinity.

There was a catch.  Given that this mission was a flyby, the craft would have only 25 minutes to take pictures, which would be saved onto a magnetic tape recorder for later transmission back to Earth. The 12 minutes a signal would take to travel between Earth and Mars made correcting any issues while the photography was in action impossible.

Each 200 x 200 pixel image would be converted from analog to a digital format and take ten hours to be sent back to earth at the rate of 8.3 bits per second.

The Red Planet has always fascinated people. That interest only grew in the late nineteenth century, when Italian astronomer Giovanni Schiaperelli claimed to have seen through his telescope, ‘canali’ on the planet’s surface. This was mistranslated into ‘canals’ in English. What Schiaparelli had seen were simply linear lines.  That detail was missed, and the ‘canals of Mars’ became a huge topic.  American astronomer Percival Lowell went so far as to produce detailed maps of the ‘canals’ he said he had seen from his observatory at Flagstaff, Arizona. If there were ‘canals’ on Mars, then surely there must be…intelligent life?

While earth-based telescopes could make out little surface detail, astronomers could see frequent, regular changes on the planet’s disc.  While some thought this could point to plant life, an explanation was tantalisingly out of reach.

With the stakes as high as this, Mars was a natural target for the Mariner program.

The mission went off without a hitch. The findings came as both a surprise and a disappointment. Mars has no magnetic field.  The images showed there were no canals and no civilisation.  What Mariner saw was, to all intents and purposes, a dead planet pockmarked with meteorite craters. Atmospheric pressure was measured at 1% of the Earth’s at sea level, while surface temperature was estimated at -100°C.

Since then, Mars has hosted a myriad of orbiters and rovers, including a helicopter. The planet has been found to be geologically diverse.  Although it is, too all intents and purposes, a desert, it does have water beneath the surface.  Billions of years ago, it is now known, that water was running on the surface to produce channels, rivers and lakes the ghostly remains of which are retelling their secrets to rovers such as Nasa’s Opportunity, Spirit, Curiosity, Perseverence and China’s Zhurong.

Mariner 4 itself outlived its planned mission, returning data until December 21 1967.  A case of $83 million well spent.


It may be fascinating to geeks and non-geeks alike, but what are the real scientific benefits (beyond Teflon and computers) have we gained from having a space program?


Stephen Phillips is an IET Content Producer, with passions for history, engineering, tech and the sciences.