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Interstellar Interlopers, Coming in from the great beyond
dudley
post Sep 15 2019, 02:48 PM
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Interesting that Borisov's Comet is considerably less reflective in the blue portion of the spectrum than are the examples given of known comets. These examples were presumably selected as the closest available match for the new interstellar interloper.
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HSchirmer
post Sep 17 2019, 12:06 PM
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Recent calculations suggest that we won't be able to get a probe to Borisov's Comet (Intersteller 2 aka "I2") with direct chemical rocket technology, but an Earth-Jupiter-Sun Oberth route should work.

QUOTE
The software shows that a mission with feasible Delta-V and direct transfer from Earth would have had to have been launched in July of 2018, using a Falcon Heavy launch vehicle, with arrival at the object in October of 2019.


The authors envision using the Oberth maneuver at the Sun in combination with a Jupiter flyby, thus leveraging the deepest gravitational wells available to us in the Solar System. The proposed trajectory is shown in the figure below, drawn from the paper. Notice that the Jupiter flyby is here used to decelerate the spacecraft toward the Sun. The Oberth maneuver at the Sun then flings the spacecraft outbound for its encounter with C/2019 Q4 (Borisov).

https://www.centauri-dreams.org/2019/09/16/...019-q4-borisov/


Well, thinking about a future "I3", perhaps a "high-speed storage orbit" ping-ponging a pair of probes back and forth between the Sun and Jupiter until they achieve extreme velocities, and wait for the next interstellar interloper. Figure two probes so that they're redundant, at opposite points of the orbit, allowing one to pursue an inbound encounter, the other to do an outbound study.
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fredk
post Sep 17 2019, 02:39 PM
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It's worth adding that the Jupiter-Sun route contemplates launch in 2030 and would arrive at the comet in 2045. Original source.
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HSchirmer
post Yesterday, 04:34 PM
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QUOTE (fredk @ Sep 17 2019, 02:39 PM) *
It's worth adding that the Jupiter-Sun route contemplates launch in 2030 and would arrive at the comet in 2045. Original source.


Should clarify, that would be sending a cube sat to Borisov using an Oberth "Jupiter- Sun drop kick"
The authors seem to imply that a New Horizons class probe to 1I/’Oumuamua might still be possible.

The huge difference in probe mass is because 'Oumuamua is on a mostly ecliptic path, while Borisov is on a mostly polar path.


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stevesliva
post Today, 01:07 AM
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Gives an idea of how long these things are nowhere near stars to thing that our not-exactly-warp-speed probes could catch them. They'll next be within several AU of a star... not soon.
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HSchirmer
post Today, 02:21 AM
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QUOTE (stevesliva @ Sep 19 2019, 01:07 AM) *
Gives an idea of how long these things are nowhere near stars to thing that our not-exactly-warp-speed probes could catch them. ...


Well, with a Jovian-Solar slingshot, you leave 3 Solar radii at 362 km/sec and then coast and arrive at ~34 km/sec.

So, about 30 months to slingshot up to 0.001% of light speed and coast down to 0.0001% light speed.


How about 0.2% of light speed in 12 hours? Seems possible, as it uses existing science and materials.

QUOTE
A fully powered plasma magnet sail using a small nuclear power source could accelerate at 0.5G and reach 400-700 km/sec (0.2% of lightspeed) in half a day.
https://www.nextbigfuture.com/2018/01/plasm...-in-1-week.html
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