Searching for spaceships in DP0.3

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#1

Hello,

For the past few months I have been working on an assignment given to me, that being the title, to search for spaceships in DP0.3. I have read through the documentation and found that it is stated that all spacecraft are already designated with the prefix “ET”. However, the assignment was to find them as if I were completely blind. So, using mainly Kepler’s laws and equations I calculated the orbital properties such as speed, eccentricity, major/minor axis, etc., and compared them to the main asteroid belt objects in the MPCORB table and the orbital characteristics of Voyager 1 and 2 during their mission while still in the solar system.

Using these calculated properties and examining them against the MPCORB and Voyager properties, I intend to find the key discerning characteristics and develop a process and query that would reliably find potential spacecraft.

The biggest issue I face right now is that I am assuming that an individual spacecraft, if it moves to a different orbit and is inconsistently observed, it will be given a different designation. My assignment says that there are two spaceships, so if that is true, I need to find something that will tell me what data points that may have different names actually belong to the same object.

My line of thinking to attack this is to further calculate the orbital properties of the objects, specifically eccentric, mean, and true anomaly.

So, my questions in short are, is this a valid method (calculating orbital properties) of finding spaceships in the solar system? Does the route of finding the orbital anomalies have any credibility?

Most of my orbital analysis relies on the heliocentricVX, VY, VZ columns which is in AU. Me and @mwiesner concluded that the data column means that “this object has the velocity of an object orbiting the sun at x AU”, is this interpretation correct?

I must note that because I am an undergrad, there is a large probability that all my math is wrong, especially considering that I have been doing most of it in topcat.

I have attached the equations I have been using, those highlighted in red are equations I am fairly certain are wrong and/or do not give me any reasonable result. In orange, one I am unsure works or not (I do not know if topcat can do any vector operations), In green, those that I am fairly certain (to my limited knowledge) are correct.

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Thanks.

#2

I can’t respond to your question about the methods as I know too little. However, the au unit for velocities is a mistake: VX, VY, and VZ columns are in au / d, and X, Y, Z, VX, VY, VZ together form an object’s position and velocity at a given time.

#3

If I understand you correctly the velocities are reported in au per day?

#4

Yes, velocities are reported in au/day even though units are listed as au.

#5

Thanks, that actually makes everything a lot more simpler. After fixing my calculated columns I was able to verify the identity of one object ID relying only on semi-major axis calculation (given of course they are not all wrong and I am not interpreting the data incorrectly again).

#6

Hi both, thanks for using the Forum.

I’ve marked @gerenjie’s response clarifying that the column units for VX, VY, and VZ are au per day as the solution to this topic, because it answered the main question blocking the analysis, which relies on a correct interpretation of the heliocentric velocities.

But, as always, please don’t hesitate to reply in thread or open a new topic if the issues persist.

And others should feel free to reply with advice here as well.