We’re running a test of the angular rate sensors. Right now we’re in stabilization mode using them. In the optical sight at 6x magnification through porthole 19, I can see Capella from the Auriga constellation in the light; it drifts slightly in roll, going one way then another by 1.5 degrees. Interesting. I decided to determine the station’s oscillation magnitudes around its axes by first centering the star in the sight. I can’t miss this chance to understand the station’s dynamic characteristics, and for the entire light period, about 40 minutes, I register the star’s drifts from the sight center and the time. From this I calculated the residual angular drift rates and transmitted them to the ground, although these parameters are recorded on a magnetic logger and the ground will get this data without our help during the comm session.

Today we again performed orbital orientation, and let me describe what it entails. This orientation is used for experiments when we need to work on the Earth or stars with precise aiming at the research object. One station axis is constantly pointed along the vertical, toward the Earth’s center, while two others lie in the local horizon plane, forming specified angles with the flight direction.

Orbital orientation is built as follows. On the ship and station there is an optical sight looking along the “-Y” axis. The sight has two fields of view — a central solid one with a 15-degree angle and a peripheral one of eight small fields arranged in sectors around a circle, looking at the horizon with a 150-degree opening, equal to the angular size of Earth from 350 km altitude. To build orientation we manually aim the station using the sight so that the Earth’s globe, like a ball, is symmetrically placed within the peripheral fields. When this is done, the station’s “Y” axis aligns with the vertical, and the longitudinal and transverse axes “X” and “Z” are in the local horizon plane.

Then the heading must be set. By observing the Earth’s motion in the central field, similar to a road passing under a car, we rotate the station around the vertical until Earth passes from one edge to the opposite along the heading line, set by the graduated circular scale to the desired heading. Orbital orientation is considered built with zero heading when the longitudinal axis “X” coincides with the flight direction.

The orientation can be performed manually or automatically using the infrared vertical reference IKV, which works on the Earth-Space thermal field boundary and constantly holds the station’s “Y” axis vertical to Earth. Heading is built using the fact that in orbital orientation with zero heading, the “X” axis lies in the orbital plane tangent to it, and the control system continuously rotates the station around the lateral axis perpendicular to the orbital plane at the angular rate of orbital revolution — 4 degrees per minute. If the “X” axis deviates from this heading — leaving the orbital plane — rotation also appears around this axis due to orbital motion. As a result, the “Y” axis begins departing from vertical. The IKV sensor detects this and commands a correction proportional to the deviation, which simultaneously serves as heading correction, returning “X” to the orbital plane.

Orbital orientation is our baseline, convenient because it’s easy to calculate rotation angles from it to any point in space. Between experiments, when no particular orientation is needed, the station drifts freely, rotating around its axes at small angular rates up to a degree per minute. In long flights, this mode is economical — we don’t load precision systems or the computing complex, and we save fuel.

To avoid tumbling uncontrollably, we build what’s called gravitational orientation, where the station stands vertically, “X” axis toward Earth. Its chief advantage is that it’s maintained passively, without control, for as long as desired and quite stably. This is convenient because we always know which portholes show Earth, where stars pass, where the Sun is — as if standing on Earth.

The physical basis of gravitational orientation relies on our station’s length (up to 40 m with ships), which causes the central gravity field to act differently than on a sphere-shaped ship. The two large masses at the station’s ends, connected by a long body, experience different gravitational forces when tilted from horizontal, creating a restoring torque that aligns the longitudinal axis with the local vertical, like a tumbler doll.

The station’s roll stability comes from its solar panels: two act like wings in one plane, and one like an aircraft’s fin in another. We orient the single panel against the direction of flight so that the residual atmospheric drag at 350 km stabilizes roll. The station would eventually achieve this orientation on its own in about a week, but we build it manually to save time.

Two most important orientation modes of the “Salyut-7” station — gravitational (left diagram) and orbital (right diagram).

This orientation mode is economically advantageous for future large long-lived orbital systems, as it requires almost no energy to maintain.

In the evening comm session, the operator let us listen to the full press conference of the second visiting expedition. There, Academician Gazenko reported that they have no concerns about our health, we maintain high work capacity, and they’re confident the planned program will be completed. At the press conference, the question was asked: is there a need for women to fly? If speaking about today — about today’s requirements and the tasks they must solve — my opinion is that everything should be determined by necessity. A woman has already proven she can do everything on equal footing with a man. But in flight, a woman’s presence complicates crew life, drawing attention in both daily life and work. There’s work to be done, but plenty of extra hassle. I believe a woman has every right to be part of a crew if she has earned it, competing with men on equal terms as a specialist in solving specific tasks in a scientific field, such as medicine, geology, astrophysics, and so on.