28
$\begingroup$

Some rockets have black-and-white patterns painted on them. For example, the Saturn V has them at the bottom of the upper stages and the SLS block 2 is supposed to have them below the payload. In contrast, the Delta rockets do not have these patterns.

At least the prototype of the German Aggregat 4 rocket had similar patterns for the purpose of estimating radial motion visually. I suppose that this cannot be the sole purpose of these patterns on more modern rockets since telemetry would provide this kind of data.

$\endgroup$
32
$\begingroup$

Those markings are called roll patterns. They make it easy to spot if the rocket is rolling (i.e. turning about its vertical axis). They were common on early rockets as a visual backup to not-so-advanced acceleration sensors; you can imagine it's difficult to detect a bit of roll in the middle of huge vibrations plus enormous vertical acceleration.

The patterns are so large they're visible from enormous distances. This photo was made from 100 km away:

Saturn V Stage Separation during the Launch of Apollo 11, July 16th, 1969. The Image was Taken with a 70mm Camera Mounted on the Cargo Door of a U.S. Air Force EC-135N Aircraft. The Rocket is 55 Miles Downrange, at an Altitude of 38 Miles.

Saturn V Stage Separation

NASA still uses roll patterns. Ares I-X had a Z-shaped pattern that works the same way: the vertical distance between the diagonal and the horizontal bar tells you how the rocket is oriented:
Ares I-X launch

The base color is usually white because that absorbs less heat than any other color. This reduces propellant boiloff. According the book N-1 For the Moon and Mars (page 13), the designers had to change the color of the N-1 from dark gray to white to keep the interior temperatures at reasonable levels. The first vehicle, N-1 L3 was mostly dark gray, N-1 L8 (the fifth planned vehicle) would have been overall gloss white.

The black areas of the roll pattern are black because the high contrast makes it easy to see the patterns.

$\endgroup$
22
$\begingroup$

The stripe patterns (generically called fiducials) are indeed for accurate visual positioning when reviewing film and photos. Telemetry can drop out, and accelerometers can fail, especially in the middle of catastrophic events, and estimating a vehicle's speed from inside the vehicle by integrating acceleration is highly error prone.

Fewer modern rockets seem to have those large black-and-white areas, I would guess because modern computer image processing techniques can easily locate smaller reference points.

$\endgroup$
12
$\begingroup$

Additionally the various ISS modules are covered in similar items, meant as targets/locators/callibrators for computer based vision systems.

Unity, Node 1 covered in target spots

The image is from this site.

Have you ever watched Mythbusters the TV show? When they want to calculate speed of fast moving things, they paint a 'ruler' behind it, tape it on high speed camera, and then calculate the speed by how many frames it takes to move a distance shown behind it.

Building a 'ruler' behind a Saturn V, that can be used, and is able to withstand a Saturn V taking off boggles the mind. It is easier to cover the Saturn V in stuff that is easy to track. Now not specifically the same use case as in MythBusters, (raw speed), but more likely for roll tracking, movements, etc.

The ISS modules are covered in targets for a slightly different reason, to allow the CanadaArm system to operate a bit more autonomously.

$\endgroup$
  • $\begingroup$ I think you inserted the image and first paragraph at the top instead of the bottom of your text by mistake. (Also, +1) $\endgroup$ – Lilienthal Dec 12 '14 at 20:12
  • 1
    $\begingroup$ That Space Vision System was abandoned years ago. It never worked very well. Hence the lack of any of these targets on the Dragon, etc. $\endgroup$ – Organic Marble Jul 2 '15 at 21:14

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.