Mariner IV

[Dobbins]

Here's a little Christmas present for NASA Space Flight Readers, personal recollections of the Mariner IV mission, the first flyby of Mars, from Bill Momsen the imaging engineer for JPL's Mariner series of missions.

"This is the story of Mariner IV, the world's first mission to the planet Mars. Among many important discoveries, it consigned the canal theory to limbo. A description of the mission and spacecraft is augmented by the author's personal experiences while associated with this historic undertaking"

http://home.earthlink.net/~nbrass1/mariner/miv.htm

[Davros]

That is a very nice read. Very personal and one to enjoy.

[leovinus]

As Mariner 4 came up in another thread, I found the post #1 link to be dead. It is on archive.org as
https://web.archive.org/web/20060102025337/http://home.earthlink.net/~nbrass1/mariner/miv.htm
and attached as PDFs as well.

Someone else can try to revive the movies at the thread

Mariner IV: "Eight Months to Mars" 1965 NASA-USIA - Video
https://forum.nasaspaceflight.com/index.php?topic=42207.0

[leovinus]

Report From Mars - Mariner IV, 1964-1965
https://ntrs.nasa.gov/citations/19660013521

To Mars- The Odyssey Of Mariner IV
https://ntrs.nasa.gov/citations/19650018349

Design And Test Performance Of Mariner IV Television Optical System
https://ntrs.nasa.gov/citations/19650019536

[Phil Stooke]

Here are the images, mapped onto a modern map by matching features.  Contemporary maps could not locate the images precisely and were based on pointing.  They typically show image 1 extending much further north than it really did.  Also note in images 1 and 2 that the white markings are clearly surface features, not clouds as often suggested at the time.

[libra]

Cross-posting from this thread
https://forum.nasaspaceflight.com/index.php?topic=56027.msg2406876#msg2406876

To extend the discussion: I was surprised that all five Lunar Orbiter took a combined 1100 pictures; also it took two weeks to film readout and beam the pictures to Earth. From lunar distances.

[laszlo]

That 2 weeks was mostly caused by the fact that the spacecraft was only visible from Earth for about 4 hours per orbit and there were only about 3 orbits per day. It also wasn't helped by the fact that the data storage medium was a reel of photographic film instead of an electronic medium.

[libra]

Ok, thank you for that. Even for 1960's analog tech I found it excessively sloooooooooow...

Somewhere on this forum (in one of the many spysats thread) I put Lunar ORbiter data rates back to back with SAMOS in LEO - and why it was found to be unworkable as spysat; despite the powerful lure (or attractivity) of near real time imaging.

[LittleBird]

Ok, thank you for that. Even for 1960's analog tech I found it excessively sloooooooooow...

Oliver Morton put the speed [edit: of Mariner IV at Mars] rather nicely in context in Mapping Mars in 2002 when he remarked that each picture's data was about the size of an *empty* Word document, and that even then he could download the whole dataset in seconds with what may well still have been a dialup modem.

[laszlo]

Ok, thank you for that. Even for 1960's analog tech I found it excessively sloooooooooow...

Oliver Morton put the speed rather nicely in context in Mapping Mars in 2002 when he remarked that each picture's data was about the size of an *empty* Word document, and that even then he could download the whole dataset in seconds with what may well still have been a dialup modem.

Again, you need to keep in mind the storage medium.  The film had to be mechanically moved from reel to reel under a flying spot scanner. The film was scanned almost 300 times per mm, so it was a relatively slow mechanical process, much slower than retrieving data from a hard drive.The scanning and transmission were of necessity linear, too. That is, the transmitter couldn't queue up data to send while the next strip of film was being moved into position. So the transmission time was set by the film movement, not by the transmitter data rate. Morton's example, while instructive concerning the amount of data collected, isn't all that applicable to the spacecraft data rates.

Edit - The scan time for a medium-res frame was 10 minutes and a high-res frame took 34 minutes

[ccdengr]

Mariner 4 did not use a film system.
https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1964-077A-01

The Mars television experiment was designed to obtain photographs of the Martian surface and telemeter them to earth. The TV subsystem consisted of (1) a Cassegrain narrow-angle reflecting telescope... (2) a shutter and filter assembly that had 0.08- and 0.20-s exposure times and used red and green filters, (3) a slow scan vidicon tube, with a 0.22- by 0.22-in. sq target, which translated the optical image into an electrical video signal...

[LittleBird]

Mariner 4 did not use a film system.
https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1964-077A-01

The Mars television experiment was designed to obtain photographs of the Martian surface and telemeter them to earth. The TV subsystem consisted of (1) a Cassegrain narrow-angle reflecting telescope... (2) a shutter and filter assembly that had 0.08- and 0.20-s exposure times and used red and green filters, (3) a slow scan vidicon tube, with a 0.22- by 0.22-in. sq target, which translated the optical image into an electrical video signal...

Indeed, we know, thanks, and it was recently discussed in Empire thread  https://forum.nasaspaceflight.com/index.php?topic=56027.msg2406790#msg2406790 -it's just that libra and laszlo are comparing the speed of playback by and comms links to the moon in case of Lunar Orbiter with that of Mariner IV at Mars ... and I realise my own post wasn't clear that Oliver M was referring to Mariner IV not Lunar Orbiter, sorry.

[WallE]

After Mariner 3's launch failed and the probe was left entombed in its payload shroud NASA rushed to assemble the backup vehicle, Atlas 288D, and probe on LC-12. Since the failure had been caused by the fiberglass payload shroud on Mariner 3, it was replaced by a metal one but this was heavier and would reduce Atlas performance, so GD/A had to make some modifications to the launch vehicle, though I'm not exactly sure what those were (removing extra telemetry measurements? I don't happen to know offhand).

While Mariner 3 was launched from LC-13, which NASA had to share with the Air Force and its Vela program, 4 used LC-12 which was completely under NASA control. Although to be honest LC-13 didn't see another launch for eight months so the pad wasn't exactly that booked up. They had to work fast because the Mars window would close and they'd be stuck waiting two years for the next one but ended up completing the work and launching only 23 days after Mariner 3.

[Proponent]

After Mariner 3's launch failed and the probe was left entombed in its payload shroud NASA rushed to assemble the backup vehicle, Atlas 288D, and probe on LC-12.

Wasn't it always planned to launch two Mariners to Mars during the window?  Dual launches seem to have been the norm rather than the exception for the Mariner program (as well as for the Voyager program, which was originally referred to as "Mariner Jupiter Saturn").  Strictly speaking, then, Mariner 4 was not a back-up.

[Jim]

After Mariner 3's launch failed and the probe was left entombed in its payload shroud NASA rushed to assemble the backup vehicle, Atlas 288D, and probe on LC-12.

Wasn't it always planned to launch two Mariners to Mars during the window?  Dual launches seem to have been the norm rather than the exception for the Mariner program (as well as for the Voyager program, which was originally referred to as "Mariner Jupiter Saturn").  Strictly speaking, then, Mariner 4 was not a back-up.

There actually was a third spacecraft.  It became Mariner 5 and went to Venus.

[WallE]

Mariner 3 was not the first or last time ill-conceived weight-saving hardware caused the loss of a mission as there was Titan 3C-12 which failed during launch when its fiberglass shroud fell off and certain Atlas flight test failures caused by lightweight aluminum components that proved less durable than steel ones. Because, surprise, lightweight materials also tend to be flimsier.

And also Atlas-Centaur AC-4 which failed because it had undersized ullage rocket tanks to reduce weight but turned out there wasn't enough propellant to stabilize the main Centaur tanks for engine restart.

And yes, Mariner 5 was a leftover from the Mars '64 program and several modifications were made including smaller solar panels as it would get more sunlight going to Venus and several instruments and the camera removed. They were also able to add a UV photometer that was supposed to go on Mariner 4 but dropped when bench testing confirmed that it could short out the camera. Mariner 5's launch was mostly successful but the Agena exhibited pressure fluctuations in the engine thrust chamber so Bell redesigned the turbopump gearbox to prevent future recurrences.

Guess the plan was to launch two probes like with the later NASA "dual" planetary missions and there was a third built as a backup in case they lost one. But then again after 3 was lost they just went and flew 4 by itself without the planned dual launch--I assume there wasn't a third Atlas-Agena vehicle available for the backup probe.

[Jim]

--I assume there wasn't a third Atlas-Agena vehicle available for the backup probe.

Was never planned.  The 3 spacecraft were in case there were problems in prelaunch processing.

[LittleBird]

After Mariner 3's launch failed and the probe was left entombed in its payload shroud NASA rushed to assemble the backup vehicle, Atlas 288D, and probe on LC-12. Since the failure had been caused by the fiberglass payload shroud on Mariner 3, it was replaced by a metal one but this was heavier and would reduce Atlas performance, so GD/A had to make some modifications to the launch vehicle, though I'm not exactly sure what those were (removing extra telemetry measurements? I don't happen to know offhand).

While Mariner 3 was launched from LC-13, which NASA had to share with the Air Force and its Vela program, 4 used LC-12 which was completely under NASA control. Although to be honest LC-13 didn't see another launch for eight months so the pad wasn't exactly that booked up. They had to work fast because the Mars window would close and they'd be stuck waiting two years for the next one but ended up completing the work and launching only 23 days after Mariner 3.

Story also nicely told at Drew Ex Machina: https://www.drewexmachina.com/2014/11/05/50-years-ago-today-the-launch-of-mariner-3/

[libra]

That blog is such a good resource... !

[WallE]

Story also nicely told at Drew Ex Machina: https://www.drewexmachina.com/2014/11/05/50-years-ago-today-the-launch-of-mariner-3/

Given that it typically took about 21 days to refurbish an Atlas launch pad and erect a second rocket

Bit of a disadvantage there compared with the Soviet program which could reuse R-7 pads in just two days.

two launch pads would have to be used to improve the chances of getting both Mars-bound spacecraft off the ground in the time available.

LV reliability was improving by 1964 but still potentially an issue and the standardized Atlas SLV core had not been adopted across the board yet; Mariner 3 and 4 were still using custom-built Atlas D vehicles tailored for the particular mission needs.

Launch Complex 12 and 13 at Cape Kennedy were chosen to support the Mariner-Mars 1964 launches. LC-12 was a NASA launch pad but it needed to be modified to support the Atlas-Agena D then reconfigured after the Mariner launch to continue supporting the Agena B for missions such as the upcoming Ranger 8 lunar probe. LC-13 was a USAF facility that was already configured to support the Agena D but would require some modifications to support the Mariner payload just as LC-12 would.

LC-13 was used for Vela in 1963-65 with the sole exception of Mariner 3 while LC-12 was used for NASA missions--Ranger, OGO, and Mariner as well as the FIRE Apollo heat shield tests but each of these required the pad to be reconfigured (also note that 15 months passed between Ranger 5 and 6 so LC-12 didn't get used at all during 1963). Plus of course Ranger used Agena B while Mariner used Agena D which necessitated further modifications.