Sampling the Unexplored Regions of Venus

Sampling the Unexplored Sampling the Unexplored Regions of Venus Regions of Venus

Sanjay S. LimayeSanjay S. Limaye

University of Wisconsin, Madison, USAUniversity of Wisconsin, Madison, USA

With contributions byWith contributions by

Kristen Griffin, Amy Lo, Kristen Griffin, Amy Lo, Ron Polidan – Northrop Grumman Aerospace SystemsRon Polidan – Northrop Grumman Aerospace Systems

And Viktor Kerzhanovich, ex-JPL and IKIAnd Viktor Kerzhanovich, ex-JPL and IKI

99thth International Planetary Probes Workshop International Planetary Probes WorkshopToulouse, FRANCE, 18-21 June 2012Toulouse, FRANCE, 18-21 June 2012

Exploring the unexplored regions of Exploring the unexplored regions of

Venus (atmosphere)Venus (atmosphere) Limaye - Limaye - 22

Why Venus?Why Venus?

• Extreme case of greenhouse effect – what can Extreme case of greenhouse effect – what can it inform us about Earth’s future climates with it inform us about Earth’s future climates with increased greenhouse gases?increased greenhouse gases?

• Inferred to have had liquid water on its surface Inferred to have had liquid water on its surface based on high D/H ratio in the the atmosphere based on high D/H ratio in the the atmosphere (below clouds) and even higher above the (below clouds) and even higher above the clouds (Venus Express)clouds (Venus Express)

• Did Venus harbor life in its past?Did Venus harbor life in its past?• Indeed, Venus has a habitable zone in the Indeed, Venus has a habitable zone in the

cloud layercloud layer• What is the ultraviolet absorber? What is the ultraviolet absorber?

Since the confirmation of the high surface temperature by Mariner 10 and the discovery of the global vortex circulation from Mariner 10, Venus has remained a puzzle



Venus SurfaceVenus Surface

• Is Venus geologically active? – Is Venus geologically active? – Volcanoes, seismic activity?Volcanoes, seismic activity?

• How would we detect surface activity How would we detect surface activity above the clouds?above the clouds?

• What caused the re-surfacing in the What caused the re-surfacing in the last few hundred million years?last few hundred million years?

• Is the spin rate of Venus changing as Is the spin rate of Venus changing as posed by recent Venus Express data?posed by recent Venus Express data?



What is the connection between What is the connection between the superrotation and the vortex the superrotation and the vortex circulation? circulation?

How deep is the How deep is the vortex vortex circulation?circulation?

Polar composites from Venus Monitoring Camera on Venus Express



Direct Sampling of Direct Sampling of Venus and its Venus and its AtmosphereAtmosphere

• OrbitersOrbiters– Magellan and Venus Express (Atmospheric Magellan and Venus Express (Atmospheric

Drag)Drag)

• Entry ProbesEntry Probes– Venera 4-8, Pioneer Venus SP1, SP2, SP3 and Venera 4-8, Pioneer Venus SP1, SP2, SP3 and

LP below 62 kmLP below 62 km

• LandersLanders– Venera 9 – 14, VeGa 1, VeGa 2 Venera 9 – 14, VeGa 1, VeGa 2

• BalloonsBalloons– VeGa 1 and VeGa 2VeGa 1 and VeGa 2

Venera 4



Direct Measurements of Venus Direct Measurements of Venus AtmosphereAtmosphere

• Venera, Pioneer and VeGa probes/landers Venera, Pioneer and VeGa probes/landers make measurements below ~ 62 to 64 kmmake measurements below ~ 62 to 64 km

• Above this altitude accelerometers Above this altitude accelerometers provided pressure/density data from which provided pressure/density data from which temperatures were derivedtemperatures were derived

• VeGa balloons measured 53-55 km VeGa balloons measured 53-55 km altitudealtitude

• Magellan and Venus Express orbiters Magellan and Venus Express orbiters aerobraking/atmospheric drag data aerobraking/atmospheric drag data provide density @ ~ 160 – 170 kmprovide density @ ~ 160 – 170 km



Why sample the atmosphere Why sample the atmosphere above 64 km?above 64 km?

• Cloud top level extends to ~ 75 km in Cloud top level extends to ~ 75 km in low latitudeslow latitudes

• Haze layers present to ~ 90 km Haze layers present to ~ 90 km altitudealtitude

• UV absorber identity still not UV absorber identity still not confirmedconfirmed

• Direct ambient three-component wind Direct ambient three-component wind measurements not availablemeasurements not available



Science RelevanceScience Relevance• UV absorber is responsible for majority of the UV absorber is responsible for majority of the

solar energy abosrbed by Venussolar energy abosrbed by Venus• The contrast features in un ultraviolet images The contrast features in un ultraviolet images

of Venus show a variety of morphologies and of Venus show a variety of morphologies and evolve on short and long time scalesevolve on short and long time scales

• The cloud motion measurements are somewhat The cloud motion measurements are somewhat at odds with the cyclostrophic flow inferrred at odds with the cyclostrophic flow inferrred from thermal structure data from thermal structure data

• No measurements of short period No measurements of short period waves/turbulence available waves/turbulence available

• The inferred angular momentum transport from The inferred angular momentum transport from cloud motions not consistent with theories of cloud motions not consistent with theories of superrotation and required angular momentum superrotation and required angular momentum transport in the meridional directiontransport in the meridional direction



Other atmospheric phenomena Other atmospheric phenomena of interestof interest in the region at and in the region at and above the cloud topsabove the cloud tops• Transition between super-rotation and Transition between super-rotation and

day side-night side circulation day side-night side circulation between 90-110 kmbetween 90-110 km

• Air Glow ~ 90-95 km from various Air Glow ~ 90-95 km from various photo chemical processesphoto chemical processes

• Wave braking transferring momentumWave braking transferring momentum• Atmospheric haze layers – what is the Atmospheric haze layers – what is the

source ? sink?source ? sink?



Lower Atmosphere Lower Atmosphere objectivesobjectives• The Kinetic Energy and Momentum per unit The Kinetic Energy and Momentum per unit

volume peak at ~ 20 km above surfacevolume peak at ~ 20 km above surface• No cloudsNo clouds• Low static stabilityLow static stability• Is the (horizontal) momentum being transported Is the (horizontal) momentum being transported

upwards or downwards?upwards or downwards?• Detection of surface activity Detection of surface activity • ““High” resolution imagingHigh” resolution imaging• Accurate lower atmosphere temperature profile Accurate lower atmosphere temperature profile

(P/V probes did not obtain measurements below (P/V probes did not obtain measurements below 13 km)13 km)





Potential platformsPotential platforms

• Low Altitude Balloons (below 50 km)Low Altitude Balloons (below 50 km)– Phase Change or Metal BellowsPhase Change or Metal Bellows

• High Altitude balloons (above 60 km)High Altitude balloons (above 60 km)– Often flown on Earth for long term duration Often flown on Earth for long term duration

flights carrying ~ 1000 kg at 35-25 kmflights carrying ~ 1000 kg at 35-25 km

• Mid Level Balloons (52 – 56 km)Mid Level Balloons (52 – 56 km)- VeGa 1 and VeGa 2 - VeGa 1 and VeGa 2

• Unmanned Aerial Vehicles (UAV)Unmanned Aerial Vehicles (UAV)– Used commonly in field experiment studies Used commonly in field experiment studies

of Earth aerosols and cloudsof Earth aerosols and clouds– Active and passive flightsActive and passive flights

VeGa


Venus (atmosphere)Venus (atmosphere) Limaye - Limaye - 1313A zero pressure ascending balloon From Viktor Kerzhanovich (2000)



What measurements are What measurements are needed? needed?

• Cloud particle size, composition, Cloud particle size, composition, distinguishing the distinguishing the uv aborbinguv aborbing particles particles

• Cloud particle shape by imaging of Cloud particle shape by imaging of captured particlescaptured particles

• Cloud particle composition?Cloud particle composition?• Vertical and horizontal wind/turbulenceVertical and horizontal wind/turbulence• Pressure, temperature densityPressure, temperature density• 3-component wind by tracking the balloon 3-component wind by tracking the balloon

motionmotion



Solar Challenger - conceived by MacCready and created by a team of engineers and model airplane builders

The Solar Challenger was the first solar powered aircraft capable of long distance flights. The aircraft designed by Paul MacCready’s AeroVironment, was an improvement on the Gossamer Penguin which again was a solar powered variant of the human-powered Gossamer Albatross. Solar Challenger featured photovoltaic cells on its wings and stabilizer, without incorporating any reserve batteries. In the year 1981, it successfully completed a 262 km flight from France to England. The Solar Challenger was designed to be more maneuverable and powerful than the Gossamer Penguin and also to withstand turbulence and sustained high attitude flight. It was three times heavier than the Gossamer Penguin, had a shorter wingspan and was more powerful. The Solar Challenger featured 16,128 solar cells powering two 3 HP motors. The motors operated

on a common shaft and drove a controllable pitch propeller.

Some possibilities that might be considered for Venus?



Concept for a Concept for a Long-lived UAV Long-lived UAV

at Venus at Venus May 2012May 2012

Kristen Griffin, Amy Lo, Kristen Griffin, Amy Lo, Ron Polidan Ron Polidan

Northrop Grumman Aerospace SystemsNorthrop Grumman Aerospace Systems



Introduction to the Introduction to the ConceptConcept

• Semi-buoyant unmanned aerial vehicleSemi-buoyant unmanned aerial vehicle– 5-50% buoyant at cruising altitudes5-50% buoyant at cruising altitudes– Sinks to altitude of 100% buoyancy and Sinks to altitude of 100% buoyancy and

floats when propellers are offfloats when propellers are off• Strawman payload is balloon payload from Strawman payload is balloon payload from

Venus Climate MissionVenus Climate Mission• Propellers provide altitude, latitude, and Propellers provide altitude, latitude, and

longitude mobilitylongitude mobility– Flight path is controllable (but not in real Flight path is controllable (but not in real

time)time)– Ability to survey large areas and/or focus Ability to survey large areas and/or focus

on regions of intereston regions of interest• Power source is solar panels and batteriesPower source is solar panels and batteries• Supported by orbiting satelliteSupported by orbiting satellite

– Orbiter delivers UAV to VenusOrbiter delivers UAV to Venus– Orbiter serves as data and Orbiter serves as data and

communications relay with Earthcommunications relay with Earth– UAV + Orbiter is a good candidate for a UAV + Orbiter is a good candidate for a

Discovery missionDiscovery mission• Entry into Venus atmosphere without an Entry into Venus atmosphere without an

aeroshellaeroshell– UAV inflates in spaceUAV inflates in space– Large surface area produces benign Large surface area produces benign

heating loads during entryheating loads during entry– Benign entry enables continuous data Benign entry enables continuous data

collection during descentcollection during descent17

Top

Front

Side



Mission and Mission and Operations Capabilities Operations Capabilities with a UAVwith a UAV• Lifetime of multiple months or greater

– Limited by atmospheric corrosion of vehicle exterior and solar panels

• Flight paths can be directed and focus on regions of interest– Altitude range of 55-70 km includes Venus’s “habitable zone”– Latitude range of at least ±30o, depending on vehicle design

• A key design trade is a day-only vehicle vs a day-and-night vehicle

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Day-onlyDay-only Day-and-NightDay-and-Night

Power sourcePower source Solar panelsSolar panels Solar panels and batterySolar panels and battery

Instrument Instrument operationoperation

ContinuousContinuous Very limited at nightVery limited at night

Flight pathFlight path Very limited; Very limited; propellers primarily propellers primarily used to counteract the used to counteract the windwind

Drift with winds; Drift with winds; propellers used to direct propellers used to direct flight to areas of interestflight to areas of interest



Sample 1-Day Trajectory of Sample 1-Day Trajectory of Day-Night VehicleDay-Night Vehicle

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DAYNIGHT

Cruise at 70 kmBalloon-like float at lower altitude throughout night

Sunrise powers propellers and raises altitude accordinglyAt sunset, loss of power to

propellers causes sink to altitude of 100% buoyancy (56 km) DAY NIGHT

Propelled South-ward latitude change

Slow North-ward drift with winds

AltitudeFully controllable during the dayAltered via propelled speedRaised / lowered at will in the 55-70 km range

LatitudeFully controllable during the dayAltered via propelled directionManeuvered at will between > ±30o



Summary of Key Advantages and Summary of Key Advantages and ChallengesChallenges

Advantages• Similar instrument capabilities

as a balloon mission• Lifetime of months to a year• Directed flight with

capabilities for global survey and localized monitoring

• Large range of accessible altitudes, latitudes, longitudes

• Data collection throughout entry from very high altitudes

• No aeroshell maximizes mass available to science mission

Technical ChallengesTechnical Challenges•Sufficient, rechargable Sufficient, rechargable

battery power to battery power to survive ~70 hr nightssurvive ~70 hr nights

•Protection of solar Protection of solar panels in Venus panels in Venus atmosphereatmosphere

•Packaging for transfer Packaging for transfer to Venus and on-orbit to Venus and on-orbit deployment sequencedeployment sequence

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HeritageHeritage

ItemItem HeritageHeritage ReferenceReference

Buoyant structures Buoyant structures on Venuson Venus

Significant Significant development of development of balloon materials balloon materials etcetc

JPL: Prototype JPL: Prototype balloon existsballoon exists

Construction and Construction and operation of operation of semibuoyant semibuoyant vehiclesvehicles

Terrestrial blimps Terrestrial blimps have similar have similar ambient flight ambient flight environmentenvironment

Northrop Grumman: Northrop Grumman: LEMV semibuoyant LEMV semibuoyant vehicle under vehicle under constructionconstruction

Use of UAVs for Use of UAVs for automated science automated science observationobservation

Terrestrial robotic, Terrestrial robotic, air-based Earth air-based Earth Science Science observationsobservations

Northrop Grumman: Northrop Grumman: GlobalHawkGlobalHawk

Autonomous Autonomous navigation and navigation and hazard avoidancehazard avoidance

Frequently used in Frequently used in planetary science planetary science missionsmissions

Northrop Grumman: Northrop Grumman: LCROSS LCROSS autonomously autonomously navigated to lunar navigated to lunar impactimpact

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Future Venus Mission Future Venus Mission OpportunitiesOpportunities

• ESA Cosmic Vision ~ 2013-2014ESA Cosmic Vision ~ 2013-2014

• NASA Discovery (NET 2015)NASA Discovery (NET 2015)

• NASA New Frontiers – 4 (NET 2016)NASA New Frontiers – 4 (NET 2016)

• Other agencies? Other agencies?

International coordination and collaborations are key to future exploration of Venus!

International Venus Exploration Focus Group – VEXAG (www.lpi.usra.edu/vexag)

http://www.lpi.usra.edu/vexag



Sunseeker by Eric RaymondBased on construction technology, the Sunseeker II is the only manned solar airplane in the world and has stayed for more time in the air than all other manned solar planes combined. This hybrid aircraft uses battery power to take off and uses solar power to maintain flight. The design integrates solar cells into the actual wing structure which also features lithium polymer batteries. A unique teetering propeller considerably reduces vibration. Under direct sunlight the Sunseeker II flies at 40 mph, undoubtedly a slow speed by aircraft standards, making it susceptible to be hit by birds.





Venus The craft would have to be capable of sustained flight at or above the wind speed, about 95 m/sec at the cloud-top level, 65 to 75 km above the surface

The intense heat and air pressure on the surface of planet Venus makes lander missions almost impossible. Instead, a mission flying in the atmosphere of the planet and closer to the surface would be particularly helpful for collection of a detailed amount of data. In year 2007, NASA formed a Science and Technology Definition Team (STDT) to study the concept of a flagship mission to Venus. According to Dr. Geofrey Landis from NASA’s Glenn Research Center, a small solar powered aircraft could fly continuously on the atmosphere of Venus and gather information on the planet’s surface and atmosphere with the ability to maneuver almost everywhere. Landis and his team, who have been studying and working on this concept since the year 2000, have presented their findings for Venus to NASA’s STDT. The airplane which would have to fold up to fit inside a small aeroshell would deploy from the shell after landing on the planet, unfold and glide through the atmosphere. Since the solar cells would cover the entire surface, the airplane would be powered by solar energy, not needing any fuel. The design drawn by the team features a wingspan of 9m and a length just under 7m. However a problem for the solar airplane to fly on Venus would be the wind and to keep it flying under the sun, the airplane must be designed to fly faster than the wind. It must also be capable of sustained flight at or above the wind speed. The aircraft can glide down to lower altitudes and then climb back, probing the cloud layers in between. Although Landis and his team have designed this solar powered aircraft basically to study the atmosphere of Venus, they are also considering using the aircraft for radar mission.

Sampling the Unexplored Regions of Venus

Documents

pioneer venus sp1

ultraviolet images of

venus monitoring camera

puzzlevenus surfaceis

spin rate of venus

recent venus express

cloud motions

cloud topstransition