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Future Venus Missions
JRehling
post Feb 21 2021, 05:24 PM
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I missed, until now, the announcement made in October 2020, that the SPICA mission had been dropped from consideration for M5, making it now a decision between EnVision and Theseus.

Venus now has two candidate missions in a competition that will choose up to two out of four, and another competition in which Venus has one out of two. If the Discovery program indeed chooses two, then the only way Venus will fail to get at least one upcoming mission is for the decision process to rank those respective candidates in literally the one most unfortunate way possible. If all those options were equiprobable, then we have an 83% probability that Venus is about to garner its first dedicated mission with a focus on the surface of Venus since Magellan launched in 1989! The Discovery selection timelines was at least notionally supposed to conclude this month, which means we may be hearing next week.
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vjkane
post Feb 21 2021, 06:57 PM
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QUOTE (JRehling @ Feb 21 2021, 09:24 AM) *
I missed, until now, the announcement made in October 2020, that the SPICA mission had been dropped from consideration for M5, making it now a decision between EnVision and Theseus.

Venus now has two candidate missions in a competition that will choose up to two out of four, and another competition in which Venus has one out of two. If the Discovery program indeed chooses two, then the only way Venus will fail to get at least one upcoming mission is for the decision process to rank those respective candidates in literally the one most unfortunate way possible. If all those options were equiprobable, then we have an 83% probability that Venus is about to garner its first dedicated mission with a focus on the surface of Venus since Magellan launched in 1989! The Discovery selection timelines was at least notionally supposed to conclude this month, which means we may be hearing next week.

To be somewhat more precise, 83% of possible combinations of mission selections would include at least one Venus mission. However, past selections have shown a low priority for Venus mission selection: 0 out of 4 in the last Discovery selection and the Venus radar mission (a heftier version of VERITAS) wasn't included as a New Frontiers finalist despite statements that it was ranked as a category 1 proposal in the reviews.

What I find intriguing is that NASA has pushed back the announcement of the selection of new Discovery missions to June, which is when the M5 selection is expected to be announced. EnVision apparently requires a NASA-provided radar system to fit within its budget. NASA and ESA could announce the selection of EnVision under the M5 program as a joint mission and then NASA selects two missions from DAVINCI+, Trident, and IVO. The downside for radar mapping of Venus in this scenario is that EnVision wouldn't begin its regular operations until ~2034, ~7 years after VERITAS would.

As a side note, there's an LPSC abstract on the Venus Emissivity Mapper instrument that all but states that the single band emissivity mapping of the surface that DAVINCI+ would do would not be able to definitively distinguish key surface compositions. (VEM would have several bands, and is included in both the VERITAS and EnVision proposals.) I suspect that the DAVINCI+ proposal argues otherwise. However, DAVINCI+ would examine limited, but high priority, areas on Venus where VEM, I believe, would map the entire planet.


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JRehling
post Feb 21 2021, 09:06 PM
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Thanks for the updates, Van, although I quietly grumble over having to wait longer.

There is certainly the potential for interaction between the ESA and NASA selections, whether or not the various agencies allow for that interaction to occur.

The extent of the capability of emissivity mapping to distinguish surface units on Venus is one of those things where we can't know until we try; Venus itself will have to answer that question. EnVision/VERITAS on the one hand and DAVINCI+ are likely complementary and I'd be thrilled to see both fly. EnVision has a more complex radar system than VERITAS, so all else being the same, EnVision might make VERITAS' incremental contributions considerably lesser than EnVision alone. Point taken, though, that VERITAS would occur first.
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vjkane
post Feb 21 2021, 09:11 PM
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QUOTE (JRehling @ Feb 21 2021, 01:06 PM) *
Thanks for the updates, Van, although I quietly grumble over having to wait longer.

There is certainly the potential for interaction between the ESA and NASA selections, whether or not the various agencies allow for that interaction to occur.

The extent of the capability of emissivity mapping to distinguish surface units on Venus is one of those things where we can't know until we try; Venus itself will have to answer that question. EnVision/VERITAS on the one hand and DAVINCI+ are likely complementary and I'd be thrilled to see both fly. EnVision has a more complex radar system than VERITAS, so all else being the same, EnVision might make VERITAS' incremental contributions considerably lesser than EnVision alone. Point taken, though, that VERITAS would occur first.

I believe that the EnVision team has firmly stated that they can't fit into their budget without a NASA-supplied radar instrument (perhaps this has changed in the last year or so?), and NASA agreed to study supplying it.

If this is true, and if EnVision is selected, then the radar instrument they've been discussing likely won't be the one they would be flying.


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