# What are the numbers on the Soyuz docking cam?

This morning I was watching another video of Soyuz docking to the ISS (Expedition 45/Visiting Crew Docks to the Space Station). The commentator noted that the two quantities $\rho$ and $\dot\rho$ in the lower-left are the range and range-rate, respectively. Retrospectively this is pretty obvious, but I had never thought about it before. This got me a little curious and I tried to look up what all the other numbers mean, with no luck.

What are the quantities displayed on the Soyuz docking camera? I'm particularly interested in the right-hand side, which looks like something to do with the orientation of the spacecraft or station.

• Omega (ω) is conventionally an angular rate, so the ω X-Y-Z are probably pitch-yaw-roll rates (maybe not in that order). Gamma, psi, theta (γ, ψ, θ) are conventionally used for angular values (but those three aren't normally used together), and I'm not sure what the angles would be relative to, or the distinction of the psi-swung-dash and theta-swung-dash elements. – Russell Borogove Sep 4 '15 at 17:31
• γ, θ and ψ are Euler angles (in degrees), the first three under КУРС (KURS, or course) are LOS (Line of Sight) angles. – TildalWave Sep 4 '15 at 17:38
• What do you mean by line of sight angles? – Russell Borogove Sep 4 '15 at 17:42
• @RussellBorogove Angle relative to target when in Line of Sight Mode (flight mode is displayed on the left, СБЛИЖЕНИЕ = convergence, approach). – TildalWave Sep 4 '15 at 17:45

## 1 Answer

Thanks to this student's Soyuz simulator:
Top left:
- $\Phi$44 : flight mode (44 is final approach)

Bottom left:
- $\rho$ : range to target
- $\dot\rho$ : range rate (closing speed)
These are calculated parameters

Top right:
- T: time
- $\omega$X, Y, Z: angular rates (roll speed on X, Y, Z axes)

Middle right:
- $\gamma, \psi, \theta$: roll, yaw, pitch attitude
- $\psi_{\pi}, \theta_{\pi}$: heading, pitch bearing angles (Soyuz position relative to ISS)

Bottom right:
- $\rho, \dot\rho$ : range and range rate (closing speed)
- $\Omega Y, \Omega Z$: line of sight angular rates (roll speeds relative to target)
These are parameters measured by Kurs. So they could compare range and range rate between the calculated course and the actual course.

• This is a great find. – Russell Borogove Sep 23 '15 at 15:03
• I wish I could +1 that student for using Orbiter =) – 2012rcampion Sep 23 '15 at 19:54
• @RussellBorogove: yes, one was the calculated range (what it should be according to the trajectory they were flying), and the other was the measured range. – Hobbes Sep 23 '15 at 20:04
• Oh, derp, was looking at the wrong thing -- sorry. – Russell Borogove Sep 23 '15 at 20:42