Here's a breakdown of the key information from the provided text:
Main Point:
Two spacecraft, Hera and Europa Clipper, have a rare possibility to study the tail of an interstellar comet called 3I/IATLAS, despite not being designed for this purpose.
* Hera: Heading to the Didymos-Dimorphos asteroid system (impacted by the DART mission). Window for observation: October 25th - November 1st.
* Europa Clipper: Heading to Europa, a moon of Jupiter. Window for observation: October 30th - November 6th.
* Comet 3I/IATLAS:
* An interstellar comet (originating outside our solar system).
* Discovered in early June.
* has a growing tail of water particles and ions.
* Recently moved out of view from Earth-based telescopes.
* Will reach its closest point to the Sun (perihelion) on October 29th.
* The Opportunity: Both spacecraft will pass "downwind" of the comet's tail in the next two weeks.
* Challenges:
* The spacecraft weren't designed to study cometary tails.
* The solar wind affects the path of the tail particles, making precise positioning for data collection difficult.
* Tool Used: Researchers are using a model called "Tailcatcher" to estimate the tail's path and where the spacecraft need to pass to collect data.