Could a New Horizons class probe aimed to fly by a Kuiper Belt object 100 AU from the Sun use its camera, built to image the Kuiper Belt object, to also measure distances to stars (and distant Solar system dwarf planets) better than what specialized observatories using the so called Solar parallax of 2 AU can do?

If a specialized instrument is needed for parallax measurements, what demands (e.g. mass) would it put on the spacecraft for carrying and operating it? I wonder if it makes sense to combine the two purposes.


1 Answer 1


To use the longer base line of 100 AU instead of 2 AU, we need measurements from both the probe in the Kuiper Belt and another probe near the earth. But the data transfer over 100 AU distance is very slow. But such parallax measurements are done for thousands to millions of stars, see the pages about the probes Hipparcos https://en.wikipedia.org/wiki/Hipparcos and Gaia https://en.wikipedia.org/wiki/Gaia_(spacecraft). The amount of data is impressive: "Gaia sends back data for about eight hours every day at about 5 Mbit/s. ESA's two most sensitive ground stations, the 35 m diameter radio dishes in Cebreros, Spain, and New Norcia, Australia, receive the data" If the data rate from the Kuiper Belt probe is only about 100 to 700 Bit/s, only some hundred stars can be measured. It would be difficult to generate the same electrical power for operation of the probe as the Gaia probe uses 1910 W. Using solar cells to generate so much power so far away from sun is impossible. New Horizons has only about 200 W available now, that is one tenth only. The launch mass of Gaia with 2029 kg and New Horizons of 478 kg are very different too.

  • $\begingroup$ Parallax measurements are a relatively small part of Gaia's mission, and reporting the position of a star needs much less data than eg determining its atmospheric composition - communication is still a challenge, but I'd estimate 3-4 orders of magnitude less data than Gaia produces. $\endgroup$ Jan 20, 2017 at 12:11
  • $\begingroup$ Wouldn't it be valuable to have better measurements of the distances (and motions) of just certain stars in the Solar neighborhood? Like Proxima's orbit, nearby stars with exoplanets, stars that might be the Sun's companions since formation. And Betelgeuse seems hard to pin down because of its variability. And maybe narrowing down the location of a planet Nine by determining the orbits of dwarf planets it has perturbed. Is that stuff maybe not as interesting as a major survey? $\endgroup$
    – LocalFluff
    Jan 20, 2017 at 15:42
  • $\begingroup$ I think fewer measurements of selected stars could be valuable too. But to get more precision using the very long base line of 100 AU, the probe in the Kuiper Belt should do angle measurements as precise as a probe near earth specially designed and built for extreme precise measurements of angles. I don't know if a probe designed for a Kuiper Belt mission could do such precise angle measurements with much less probe mass and electrical energy. $\endgroup$
    – Uwe
    Jan 23, 2017 at 8:16
  • $\begingroup$ not related here, but any thoughts? german.stackexchange.com/q/61157/38291 $\endgroup$
    – uhoh
    Sep 26, 2020 at 12:39

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

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