th e ex p loration of Ve n u s · th e ex p loration of Ve n u s. c u rr e n t u nde rs ta ndi n g , o p e n q u es tio n s , a n d n e x t s te p s. c o l i n wi l s o n | p a u

t h e e x p lo ra t io n o f V e n u sc u r r e n t u n d e r s t a n d i n g , o p e n q u e s t i o n s , a n d n e x t s t e p sc o l i n w i l s o n | p a u l b y r n e | r i c h a r d g h a i l | m a r t h a g i l m o r e | s u z a n n e s m r e k a r | a l l a n t r e i m a n | s e a n s o l o m o n

L P S C 2 0 19 | 50 Ye a rs of P la n e ta ry S c ien c e

Slides credit: Paul Byrne (NCSU)

intro d u c tion | Ven u s fr o m afar | th e atm o sp h e re | th e surfa c e | th e interior | su rp risin g find i n g s | op en q u e stion s | n e xt ste p s

t h e e xplorat ion of V e n u s

im a g e cre d it: É de r Ivá n

L P S C 20 19 | 50 Ye a rs of P lan et a ry S c ience

Venus1960s 18

1970s 10

1980s 7

1990s 0

2000s 1

2010s 1

Moon

1950s 13

1960s 63

1970s 22

1980s 0

1990s 4

2000s 11

2010s 13

intro d u c tion | Ven u s fr o m afar | th e atm o sp h e re | th e surfa c e | th e interior | su rp risin g find i n g s | op en q u e stion s | n e xt step s

a n Earth -s ize world in t h e h a b itable z o n e

Mariner 2 (1962)

h i g h t e m p e ratures in lower atm osp h ere

n o resolvable m a g n etic field

Gold stone (1962)

retrog ra d e rotation

8 2% Earth m a s s

95% Earth radiu s

0 .72 A U

L P S C 20 19 | 50 Ye a rs of P lan et a ry S c ience b y rn e et al. |2019.03.20 |3


a s k y b y turns hospitable a n d lethal

Ve g a ba llo o ns (1985)

h i g h ly variab le a t m o s p h eric co n d ition s

Earth - like co n d ition s ~50–65 k m

g lobal c l ou d layer

H 2S O 4 c l ou d s

96.5% C O 2

h i g h D / H ratio

s u p er- rotat ing a t m o s p h ere



hell m a d e real

740 K, 93 b a r b a sa ltic lith o l og y

Ve n e ra 13 an d 14 (1982)

p h oto s o f th e surfac e

se d im e n t ary- like roc k s

first reco rdin g of s o u n d o n a n other p lanet

g rou n d im a g e cre d it: M attia s M alm er



a wor ld without m o d ern plate tectonics

s o m e volcanic reg ion s co rresp o n dto u p w ellin g

d ifferentiated interiorMagel la n (1990 )

near- g lobal im a g e a n d to p o g ra p hic co vera ge

th icke r crust for so m e high - standin g terrain

d ee p ly co m p e n sated lo w la n d ss u g g e st d o w n w ellin g

im a g e cre d it: N a tion a l G e o g ra p h ic



a relatively y o u n g surfa c e ?

n o C aloris/ S PA / H ellas

d istrib ut io n in d ist inguisha ble f rom ra n d o m

Magel la n (1990 )

~90 0 id ent ifie d craters

n on e few er th a n ~3 k m in d ia meter



a relatively a c tive surfa c e ?

a c tive volcanism ?

te m p orally variab le S O 2

Ve n u s E x p re ss (20 0 6)

d ete c t io n of transient h o tsp o ts

h ig h e m iss iv ity m a y d en ote re c e n t lavas

im a g e cre d it: h d -w a llp a p ersd o w n lo a d .c o m



a relatively m o bi l e su rfac e ?

evid e n c e for lateral m o t io n

Magel la n (1990 )

w id esp read te c tonic d eformatio n

m o re d eformatio n th a n M ercury, Mars, or th e M o o n



w h a t d i d e arly V e n u s look lik e ?

Mariner 5 (1967)

P io n e e r Ve n u s (1978 )

p o s sib le loss of a t m o s p heric w ater

formerly p resent o c e a n s?

im a g e cre d it: N A SA/G S F C



is there continental cru st?

h i g h ly d efo r m e d terrain

Ve nera 8 (1972)

e levated radio g e n i c e le m e n t a b u n d a n c e s

stratig ra p h ical ly old e st m a t erial



t w o Earth -l ike wor lds?

d o these p lanets h ave a shared history?

if n o t, w h y n o t?

w h en d id th e ir p ath s d iverge?


im a g e cre d it: N A SA/G S F C

intro d u c tion | Ven u s fr o m afar | th e atm o sp h e re | th e surfa c e | th e interior | su rp risin g find i n g s | op en q u e stion s | n ext step s

so w h e r e d o w e g o f rom here ?

co m p o s ition, evo lut io nof th e a t m o s p h ere

co m p o s itio n of surfac e m a t eria ls

structure (an d a ct iv ity)of th e interior



w e n e e d to u n d erstan d V e n u s in its o w n r i g h t…



…but also in terms of how it c o m p a r e s with other wor lds , b e c a u s e :



V e n u s w ill he l p u s u n d e r s t a n d the rules that g o v e r n E a rth -l ike worlds


intro d u c tion | Ven u s fr o m afar | th e atm o sp h e re | th e surfa c e | th e interior | su rp risin g find i n g s | op en q u e stion s | n ext step sVenus exploration vehicles: a range of platforms for different science goals

European Venus Explorer (EVE): a balloon mission in the heart of the habitable layer

• Helium superpressure balloon, 53-57 km float altitude.

• Follows heritage of French/Soviet Vega balloons (1984)

• Benefit from benign climate: 10 – 50 °C, atmospheric densities like those found at 0 to 5 km altitude on Earth.

• Ideal platform for trace gas mass spectrometry (thermally stable)

• Explore clouds of liquid water (albeit mixed with sulphuric acid).

• Use high winds of 200-250 km/h to circumnavigate the planet in 5-8 days.

T. Balint

thriving in the clouds

3. Mobile robotics

1. Short-duration (~ 1 hr) Venera-style landers

2. High-temperature ambient-temperature landers

a pathway to surface operations

EnVision Venus orbiter

Finallist in ESA’s M5 Space Science mission competition

Strong NASA participation (being defined)

Currently entering phase A study (2019-2021)

Selection expected summer 2021.

Launch in 2032

Aerobraking 2033 - 2035

Nominal science mission 2035-2038

Three science themesActivity – How geologically active is Venus today?

History – How have Venus’ surface and interior evolved?

Climate – How did Venus’ atmosphere become so hostile?

EnVision radar: the value of spatial resolution

• Radar has come a long way since the 1980s when Magellan radar was developed.• Magellan radar spatial resolution was 100 m at best.• Modern radar could enable spatial resolution approaching 1 – 5 m.• Modern radar has lower noise, better radiometric resolution, clearer imagery.

Mars at 150 m/pxl (Viking) 20 m / pxl (MGS) 1 m/pxl (MRO)

EnVision : much more than just high-res radar

VenSpec-UMapping SO, SO2 and UV absorber at cloud top. 210–240 nm (@ 0·2 nm), 190–380 nm (@ 2 nm), ~10 km spatial resolution

VenSpec-HMapping of near surface atmosphere H2O, HDO at 0–15 km @1·08–1·2 μm, H2O, HDO, OCS, SO2 at 30–40 km @ 2·44–2·47 μm, ~100 km spatial resolution

VenSpec-MMapping mineralogy by surface emission at 6 channels 0·82–1·2 μm at <50 km resolution

VenSARSurface morphology, 1–30 m, polarimetry, cm changes by DInSAR @ 3·2 GHz, 5 × 38 km radiometry at 1 K precision,

SRSSubsurface radar down to 1000 m depth and ~10 m resolution @ 9 MHz

Radio ScienceTwo-way mapping, radio occultations, gravity field, k₂ love number

base image © C. Hamilton

EnVision science payload

EnVision warmly invites your participation and support.

More information: www.envisionvenus.eu

Lead proposer: Richard Ghail (Royal Holloway)

Deputy Leads: Colin Wilson (Oxford U) & Thomas Widemann (Paris Obs)

th e ex p loration of Ve n u s · th e ex p loration of Ve n u s. c u rr e n t u nde rs ta ndi n g , o p e n q u es tio n s , a n d n e x t s te p s. c o l i n wi l s o n | p a u

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