Explorer 1 question

In films of the Explorer 1 launch, after it gets off the pad a little,
there is a light on the rocket, at about the top of the first stage.
You can see it in the following video, starting about 2:45 into the
video. What is that light? Is it a reflection off something or what?


https://www.youtube.com/watch?v=NfMIrKkzRx8

Excellent question! This caused me to dig rather deep and still haven't found anything totally satisfactory. The issue is that the Jupiter-C is a bit of a special duck. Primarily used for warhead nose cone re-entry profiling, it was known back in the late 50's that this rocket COULD put a satellite in orbit through use of a fourth stage but no program was in place at the time to pursue it. Perhaps Cold War ethos wanted to keep this capability under wraps for as long as possible. Even MORE interesting is that the Jupiter-C program was mothballed and the 3 rockets of this variant were purposefully mothballed pretty much by one general acting on his own initiative rather than being dismantled as originally planned, in order to keep them available.

All that being said, the issue here is with what is called the "AFT" section of the rocket. This is the skirt that sits atop the Redstone rocket propulsion unit (all part of the first stage). So far I have been able to uncover a decent schematic for this section only for the operational Redstone ballistic missile. As such this appears very differently from the one used in the Jupiter-C configuration:

See page 31 of this document:

http://www.myarmyredstonedays.com/pd...dstone_001.pdf

Here it looks like the jet vanes and air nozzle assemblies were removed for the Jupiter-C configuration, however the 4 counterforts remain. Also in the -C configuration the instrumentation section is more conically shaped and supports the rotating "tub" assembly used in stages 2, 3 and 4, absent in the operational missile configuration.

Here are a couple of pictures here that better show the -C AFT variant he

http://upload.wikimedia.org/wikipedi...Explorer_1.jpg

http://www.enterprisemission.com/Jupiter-C_Gantry.jpg

Note: I don't endorse the content of the 2nd link but it does have a good photo of the upper end of the Jupiter-C that can withstand significant enlargement.

So there are two possibilities here. Note the first picture shows light emitting from the AFT section in two places. First as white light being emitted from the wide end (bottom) of each of the counterforts and an additional red light being emitted at two points nearly 180 degrees apart. Normally I'd go with the white light from one of the counterforts, but for the video you provide, it looks to be in the wrong place and only one light source is visible in the film. So I am at a loss.

There is one other remote possibility but I think that highly unlikely. Page 81 of the first cited document talks about the positioning of a porro prism used in conjunction with a "laying kit" to "orient the missile to allow the lateral guidance system to be keyed to the theoretical ballistic path from launcher to target". Perhaps this object was replaced in the -C AFT skirt with something that also emits light! It is in about the correct position.

On Fri, 12 Dec 2014 16:40:17 -0800 (PST), David Spain
wrote:


Here are a couple of pictures here that better show the -C AFT variant he

http://upload.wikimedia.org/wikipedi...Explorer_1.jpg

In that photo I see three reflections off the protusions. That might
be what I see in the film.

PS: The last time I took the KSC "Then and Now" tour, I asked one or
two of the "old hands" at that pad, and they didn't know anything
about it.)

On Fri, 12 Dec 2014 16:40:17 -0800 (PST), David Spain
wrote:

I am convinced that this light is issuing from the rocket and is not a reflection. ...

That is what I thought at first, but later I convinced myself that it
was a reflection of the protusions. But, as you pointed out, only one
is visible in the film, and it is pretty bright.

There is a pole that runs up the side for telemetry or something that
falls off right before lift off - could it have something to do with
that?

On 12/12/2014 02:17, Jan Philips wrote:
In films of the Explorer 1 launch, after it gets off the pad a little,
there is a light on the rocket, at about the top of the first stage.
You can see it in the following video, starting about 2:45 into the
video. What is that light? Is it a reflection off something or what?


https://www.youtube.com/watch?v=NfMIrKkzRx8

Don't know if it helps, but here's a good quality photo that appears to
show the light.


http://www.replayphotos.com/apphotostore/space-print/jupiter-c-missile-blasts_198073.cfm

To my eyes the light appears to be on the shroud covering stage 3. Stage
3 consisted of a cluster of 3 Sergeant solid-propellant motors.

It's also worth searching for Juno I & Juno II.

Taking my own advice I found that there was a 3-volume JPL Technical
Report published in 1960 that was a "summary of Jet Propulsion
Laboratory space-flight activities utilizing the Juno I and Juno II
rocket-vehicle configurations."

It is Technical Report No. 32-31.

It may be available elsewhere, but I found it he

www.scribd.com

Vol. 1 98 pp covers Juno I from 1954
Vol. 2 92 pp covers Juno II & Pioneer III/IV
Vol. 3 34 pp covers Juno II & earth satellites

Vol. 1 would appear to be the most interesting.

This website was also of interest:


http://ipmsstockholm.org/magazine/2005/06/stuff_eng_davidoff_explorer.htm

--

Brian W Lawrence
Wantage
Oxfordshire

On Sun, 14 Dec 2014 14:07:15 +0000, Brian Lawrence
wrote:

Don't know if it helps, but here's a good quality photo that appears to
show the light.

Thanks for all of that. To me, it looks like where the telemetry pole
(or whatever it is) hooked in, based on the height and location
relative to the stripes. (Just eyeballing it - no measurements.)

On Thu, 11 Dec 2014 21:17:24 -0500, Jan Philips
wrote:

In films of the Explorer 1 launch, after it gets off the pad a little,
there is a light on the rocket, at about the top of the first stage.

I don't remember if anyone pointed out this photo, but it shows what
seems to be reflections off three of the protusions. But the light
I'm talking about looks brighter and it is seen only in some views
(thus only one).

https://commons.wikimedia.org/wiki/F...Explorer_1.jpg

Still searching for a good pictorial schematic of the "Jupiter-C" skirt, which I believe is the source for your light. It could be the telemetry port, that looks to be in the proper position based on the video.

I've searched through much of the Redstone and ABMA material that is on-line. Beginning to wonder if the skirt and instrumentation package that sits atop the stretched Redstone was a "JPL special" since the Jupiter-C which is actually not derived from a Jupiter missile, but a Redstone adapted for high altitude research had many components unique to that configuration, especially in the instrumentation and skirt that sat atop the rocket. Could this have been work performed at JPL instead of ABMA? I believe that is where the Explorer satellite originated from. But of course the skirt, instrumentation section and spinning "tub" all pre-date Explorer I and are an integral part of the "Jupiter-C" design used to test nose cone re-entry by a few years. However, it could be that JPL still played an important role in the development of these special adaptions. Need to dig further into "Project Orbiter" and JPL documentation stream.

So ironic that there is plenty of pictorial documentation out there on the rocket itself AND even the upper stages (2, 3 and 4). But the instrumentation & steering nozzle skirt, not so much, and I don't think it's a classification issue either as most of this material was declassified as early as 1964!

Dave