what is the known composition of Oumuamua?

The true composition of Oumuamua is still unknown, as it is a small, rapidly moving object that was only observed for a short period of time as it passed through our solar system.

However, scientists have made some educated guesses based on its properties and behavior. Oumuamua is elongated and has a reddish color, which suggests it is made of metal-rich rock or carbon-rich materials. It is also highly reflective, indicating it may be coated in a layer of ice or other highly reflective material.

Some have speculated that Oumuamua could be a comet or asteroid, while others have proposed more exotic explanations, such as it being an interstellar spacecraft or a fragment of a larger object that was ejected from a nearby star system. However, there is currently no concrete evidence to support any of these hypotheses.
You mean we have no instruments that can detect the composition of Oumuamua?
Oumuamua was observed by several telescopes and instruments during its brief passage through our solar system, but none of them were able to determine its composition directly.

One reason for this is that Oumuamua was moving extremely fast and was only visible for a short period of time. This made it difficult to get a detailed look at its surface features or to perform any in-depth analysis of its composition.

In addition, Oumuamua was too small and distant to be studied using spacecraft, which would be the ideal way to get detailed measurements of its composition.

Scientists have been able to make some educated guesses about Oumuamua’s composition based on its properties and behavior, but until we are able to study another interstellar object up close, we may not know for certain what it is made of.
How about its gravitational influence, could we not extrapolate its density from that?
Unfortunately, it was not possible to measure Oumuamua’s gravitational influence directly because it was moving too fast and was too small to be tracked accurately. Therefore, we cannot extrapolate its density from its gravitational influence.

However, astronomers were able to measure Oumuamua’s trajectory and speed accurately, which allowed them to estimate its mass and density indirectly. By assuming a plausible range of sizes and shapes for the object, scientists were able to make estimates of its density based on its observed trajectory and speed.

Based on these estimates, Oumuamua is thought to be very elongated and have a low density, which is consistent with the idea that it is a loosely-packed conglomerate of ice and rock fragments held together by gravity. However, these estimates are uncertain and should be treated as rough approximations until more data becomes available.
At what point did this Oumuamua change its speed and trajectory and by how much?
Oumuamua’s speed and trajectory changed as it passed through the inner solar system, under the influence of the Sun’s gravity. However, these changes were very small and difficult to measure precisely.

Based on observations, scientists have determined that Oumuamua’s trajectory was deflected slightly by the Sun’s gravity, which caused it to accelerate slightly as it passed by. The exact amount of this acceleration is difficult to determine, but it was estimated to be around 0.00009 meters per second squared.

This acceleration caused Oumuamua’s trajectory to bend slightly, which scientists were able to detect and use to estimate its path through the solar system. However, the acceleration was too small to have a significant effect on Oumuamua’s overall speed, which remained at around 315,000 kilometers per hour (196,000 miles per hour) throughout its passage through the solar system.
Using Oumuamua’s know trajectory, will it ever return to this system?

Based on its observed trajectory and speed, Oumuamua is not expected to return to our solar system.

Oumuamua was moving very fast as it passed through our solar system, and its trajectory was highly hyperbolic, meaning it was on a path that would take it out of our solar system and into interstellar space. This trajectory suggests that Oumuamua was not bound to our Sun’s gravity and was likely an interstellar object that was passing through our solar system on its way to another star system.

Although it is always possible that some unknown force or interaction could cause Oumuamua to return to our solar system at some point in the future, based on our current understanding of its trajectory and speed, this is highly unlikely.
Is there any way to estimate its focii?
Yes, it is possible to estimate the focii of Oumuamua’s hyperbolic trajectory.

A hyperbolic trajectory is defined by two focii, which are the points in space around which the object would orbit if it were on a closed orbit rather than a hyperbolic trajectory. To determine the focii of Oumuamua’s trajectory, scientists can use the properties of the hyperbola and the observed trajectory of the object.

Based on the available observations, scientists have determined that Oumuamua’s trajectory had an eccentricity of around 1.2, which is higher than the eccentricity of any known Solar System object. This high eccentricity indicates that Oumuamua is an interstellar object that was not bound to our Sun’s gravity.

Using the observed eccentricity, along with the known distance and speed of Oumuamua as it passed through the inner solar system, scientists have been able to estimate the location of the focii of its hyperbolic trajectory. The focii are located at points that are beyond the orbit of Neptune, well outside the boundaries of our solar system.

It is important to note that these estimates are based on the limited observations of Oumuamua’s trajectory, and they may be subject to revision as more data becomes available.