Venus missions that lost the competition

Discovery, NASA's line of cost-capped planetary missions, has been filled by open competition since 1994. Each call brings in a few dozen proposals led by principal investigators; NASA names a handful of finalists, pays them to refine their designs, and then picks one or two to build. By law the agency does not publish the losing proposals, so what survives of them is what their teams chose to present at conferences and in papers. This page gathers the Venus bids that can be documented that way, from the Discovery line and the larger New Frontiers line, together with two European efforts, Lavoisier and the European Venus Explorer. Two NASA concept papers that have not been traced to any competition are included too, because they belong to the same search, after Magellan, for a way back to Venus.

Those two show how wide the thinking ran. The Venus Interior Structure Mission (VISM), described by E. R. Stofan and colleagues at JPL in a 1993 workshop report, would have set three seismometer landers in a triangle, two about 250 km apart and the third 1,000 km away, with an orbiting carrier relaying their data. To last six months to a year on the surface, each lander would use a radioisotope heat source driving a Stirling engine to keep its interior at 25 °C and make electricity. At NASA's Glenn Research Center, Geoffrey Landis argued from 2001 that Venus suits a solar aeroplane: above the clouds sunlight is comparable to or stronger than on Earth, the pressure is Earth-like, and the planet turns so slowly that an aircraft keeping pace with the roughly 95 m/s wind at 65 to 75 km could stay in daylight without batteries for the night. Glenn's 2004 design was sized to fit a small aeroshell on a Discovery-class mission. Neither concept has been traced here into a formal proposal.

Discovery's 1994 call drew 28 proposals, three of them for Venus: a Venus Composition Probe from Larry Esposito of the University of Colorado, the Venus Environmental Satellite from Kevin Baines of JPL, and the Venus Multiprobe Mission (VMPM) from Richard Goody of Harvard. On 28 February 1995 NASA made VMPM one of three finalists. Its 16 small probes, modelled on the Pioneer Venus small probes, would have fallen from 60 km to the ground with temperature and pressure sensors four times more sensitive than Pioneer's, while four radio telescopes around the Pacific rim tracked their signals to measure winds to 0.05 m/s or better. The target was the superrotation, which Goody's team called a major unsolved problem of planetary science for over 30 years. VMPM would have launched on a Delta II in June 1999 for $202 million. On 22 November 1995 NASA chose Stardust, which it said was rated highest in scientific content.

VESAT came back stronger. Its 1994 description placed a small orbiter in a circular orbit 30,000 km up, inclined 45 degrees, from which it would map the deep atmosphere's winds, temperatures and trace gases in three dimensions every day, with operations cheap enough to run from a university. In the next round, on 23 April 1997, NASA made it one of five finalists: an orbiter led by Baines carrying an imager, a near-infrared spectrograph, a temperature mapper and an X-band radar, at a total cost of $173 million. On 20 October 1997 NASA picked Genesis and CONTOUR. The 1994 paper's author list begins with F. Taylor and ends with Baines, while NASA's releases name Baines as the proposer, the role that counts in Discovery.

Thirty proposals answered the 1998 call, and on 12 November NASA gave five of them $375,000 each for four-month studies. One was the Venus Sounder for Planetary Exploration, Vesper, from Gordon Chin of NASA Goddard: an orbiter with four instruments to measure the composition and circulation of the middle atmosphere, at $195.8 million. A balloon bid submitted that June by Ronald Greeley of Arizona State University with JPL, the Venus Exploration of Volcanoes and Atmosphere (VEVA), did not make the cut. VEVA would have floated two balloons at 60 km for seven days, each dropping a large chemistry sonde on arrival and later four small imaging sondes onto targeted sites; 5 km above the ground a small gliding parachute would open to slow each sonde, so that it could send pictures up to its balloon near the surface (the paper's general multisonde concept puts the braking at about 3 km and allows 15 to 30 minutes of imaging). On 7 July 1999 NASA picked MESSENGER and Deep Impact.

Chin's team tried again. On 30 October 2006 Vesper was one of three missions given $1.2 million concept studies under a $425 million cost cap, described by NASA as a Venus chemistry and dynamics orbiter. A 2011 conference summary by Chin, which does not say which round it describes, lists three investigations, a submillimetre line spectrometer behind a 50 cm telescope, a near-ultraviolet and infrared imager, and radio occultation, from a polar circular orbit over two Venus years; the 1998 release had counted four instruments. NASA's release of 11 December 2007 announced GRAIL instead.

Baines, meanwhile, turned to balloons. The Venus Aerostatic-Lift Observatory for in-situ Research (VALOR), proposed to Discovery in 2004 and 2006 according to his team's later abstracts, would have floated, as the team described it in 2009, near 55 km in the middle cloud layer for several weeks, drifting north from temperate latitudes towards the polar vortex. It would have sampled all the noble gases and their isotopes, xenon and krypton included, while radio telescopes on Earth measured its winds in all three components. Neither bid was selected. In 2008 the team described Nuclear Polar VALOR, a month-long balloon over a pole powered by an Advanced Stirling Radioisotope Generator, since sunlight there is too weak; it was one of nine NASA-funded studies of missions that could use the new generator.

Radar was the next idea. In 2009 Virgil Sharpton of the University of Alaska Fairbanks, with Boeing and Alliance Spacesystems, presented RAVEN (RAdar at VENus), a Discovery mission of about $425 million built around the C-band radar made for Canada's RADARSAT Constellation. In each Venus day it could image about a quarter of the planet at 30 m per pixel, or about 3% at 3 m, against Magellan's roughly 100 m. NASA's 2010 call drew 28 proposals; from NASA's counts by destination, the blogger Van Kane tallied seven for Venus, four of them reportedly radar mappers. None was among the three finalists named on 5 May 2011.

Of the 27 proposals sent in for the 2014 call, two Venus missions reached the final five on 30 September 2015: DAVINCI, a descent probe led by Lori Glaze of Goddard, and VERITAS, a radar and infrared orbiter led by Suzanne Smrekar of JPL. On 4 January 2017 NASA picked Lucy and Psyche. Esposito, with J. R. Hall and T. Schofield, had presented a Venus Atmosphere and Surface Explorer (VASE) at a planetary science meeting in November 2014; its abstract could not be opened for this page, so neither its design nor whether it was submitted is described here. In September 2019 Esposito and his team at the Laboratory for Atmospheric and Space Physics (LASP) presented HOVER, the Hyperspectral Observer for Venus Reconnaissance, as a proposed mission: an orbiter for the clouds, chemistry, circulation and rock types of Venus and for signs of volcanic eruptions, with the Southwest Research Institute and the University of Cologne as partners. A news report in Indonesian that October listed it beside DAVINCI and VERITAS as a Venus proposal before NASA, but no NASA or team document found for this page confirms that it was formally entered in the 2019 Discovery round. The four finalists named on 13 February 2020 included DAVINCI+ and VERITAS and not HOVER, and on 2 June 2021 NASA selected those two to fly.

In the larger New Frontiers line, the Venus bids answered one standing theme, the Venus In Situ Explorer (VISE). The 2003 decadal survey pictured it as a lander that analyses the atmosphere on the way down, takes a core of the surface, and then inflates a balloon to carry the sample into cooler air for slower analysis. Van Kane noted in 2009 that, as far as he knew, no New Frontiers proposal had been that elaborate. The theme stayed on NASA's list all the same: it was one of six allowed in the New Frontiers 4 call and one of seven NASA named for New Frontiers 5 in November 2020.

Esposito's Surface and Atmosphere Geochemical Explorer (SAGE) went furthest. JPL's Team X worked up a SAGE baseline in March 2003, and a NASA chart from that September shows two landers, one for the plains and one for tessera, each descending in under an hour and working two hours on the ground; Van Kane links this two-lander version to the second New Frontiers competition. In December 2009 SAGE became one of three New Frontiers 3 finalists, each given $3.3 million for a one-year concept study, and the Planetary Society described a probe that would take data on the way down, land, and measure rock both as found and after abrading its weathered skin. Esposito's October 2009 slides, as summarised on Van Kane's blog with notes by Bruce Moomaw, gave about an hour of descent, about three hours on the surface, an arm reaching 3 to 10 cm into the ground, and a combined laser-induced breakdown and Raman spectrometer plus a neutron-activated gamma-ray spectrometer for the rock. On 25 May 2011 NASA announced OSIRIS-REx, noting that a mission to the surface of Venus had been among the three concept studies reviewed.

New Frontiers 4 drew 12 proposals in April 2017, and two were Venus landers. VISAGE, Esposito's successor to SAGE, was a lander dropped by a flyby carrier that relayed its data; in a few hours on the ground, with no control from Earth, it would drill samples from two depths, bring them inside for analysis, and photograph the drill sites before and after. VICI, the Venus In situ Composition Investigations led by Lori Glaze, would have sent two landers to the tessera highlands, which are thought to be the oldest surviving surface on the planet. Each carried a mass spectrometer and a tunable laser spectrometer for the descent, and on the ground a laser instrument firing through a window plus a gamma-ray spectrometer. On 20 December 2017 NASA chose CAESAR and Dragonfly as finalists and gave VICI technology money to develop its Venus Element and Mineralogy Camera to operate under the harsh conditions on Venus.

A third Venus team entered New Frontiers 4 with an orbiter. The Venus Origins Explorer (VOX), led by Suzanne Smrekar of JPL with the German Aerospace Center, paired an orbiter carrying the VISAR interferometric radar, the VEM emissivity mapper and Ka-band gravity tracking, the same three investigations VERITAS carries, with an Atmosphere Sampling Vehicle that would dip into the well-mixed atmosphere and hand a gas sample to its VOCE instrument for noble gas measurement. VOX was not a finalist either.

The Venus In Situ Explorer is still waiting. Once DAVINCI, VERITAS and EnVision had been chosen, NASA dropped it from the New Frontiers 5 themes in September 2022, and its draft call of January 2023 left it out; a National Academies committee, naming programmatic balance as the main reason, agreed in February 2025, while calling VISE a high priority for later rounds. NASA has not yet issued the final call: its planetary science director, Louise Prockter, said in March 2026 that it was expected in 2027. The decadal survey for 2023 to 2032 lists VISE among eight themes for New Frontiers 6, asking for what the losing landers promised: atmospheric cycles, chemistry between surface and air, and the make-up of surface rock, studied in ways that cannot be managed from orbit or from a single descent profile.

Europe's probe-and-balloon proposals of this period came out of Paris. Lavoisier, led by Eric Chassefière of the Service d'Aéronomie with laboratories in eight countries, IKI in Moscow among them, went to ESA's call for the flexible missions F2 and F3 at the beginning of 2000. It paired a descent probe for noble gas and isotope measurements with three small helium balloons floating at just 10 km, where the dense air lets a 2 cubic metre balloon lift up to 60 kg. Carried by winds that the team put at typically a thousand kilometres a day even low down, the balloons would work for days or weeks and then be deflated to land. ESA did not select it for assessment study. A CNES seminar in July 2004 recorded that Lavoisier had also been put forward in a 2002 call for ideas as an ESA cornerstone mission, and that CNES's own Solar System working group was not then putting new Venus missions forward.

Chassefière's next bid was larger. The European Venus Explorer (EVE) went to ESA's opening Cosmic Vision call in 2007 as a medium-class mission with Russian and Japanese partners. A balloon between 50 and 60 km (45 to 60 km in the letter of intent) would carry a gas chromatograph mass spectrometer once around the planet in about seven days; a Russian descent probe would fall for 60 minutes and work 30 minutes on the surface, aiming at the tesserae; and an orbiter would relay their data and then do its own science for two years. On 17 and 18 October 2007 ESA's Space Science Advisory Committee chose its candidates from 50 proposals, and EVE was not one of them. Its authors later wrote that it lost for programmatic reasons while being rated highly for science.

Japan's contribution was an unusual balloon. EVE's papers describe an optional JAXA balloon filled with water vapour, floating at 35 km below the clouds. Naoki Izutsu and Takeshi Imamura of JAXA and Manabu Yamanaka of Kobe University explained the concept, then under study by ISAS's balloon engineering group, on the old PLANET-C (Akatsuki) project website; Imamura was also one of EVE's authors. In their account, water travels to Venus as liquid in a thousandth of the volume of gas, boils into steam below 42 km, and lifts a 1 kg system that would float for a month or more at about 35 km, where the air is 180 °C at 5.8 bar and the wind circles Venus in about 10 days.

Seen from Moscow, EVE offered a way to merge with Venera-D. V. Karfidov's Russian-language catalogue describes a 2007 proposal for a joint mission: an ESA orbiter based on Venus Express, a Russian lander of 170 kg with 25 kg of instruments, and a European balloon plus a low-flying Japanese one at about 35 km. IKI's 2008 annual report confirms that its scientists worked out the science tasks and a 25 kg payload for a 170 kg descent craft for EVE. The timings differ by source: the EVE papers give 60 minutes of descent and 30 on the surface, while the Russian catalogue by V. Karfidov gives 65 minutes and 15 to 30. Had the joint mission gone ahead, Karfidov writes, Russia would have put off its long-lived lander indefinitely, but no mutually acceptable solution with ESA was reached.

What EVE was also depends on who describes it. Karfidov's catalogue says ESA considered EVE in the early 2000s under the name Venus Entry Probe, and describes it with two spacecraft, a Venus Polar Orbiter and a Venus Elliptical Orbiter. ESA's own page presents the Venus Entry Probe as one of its technology reference studies: those two orbiters plus a balloon at 55 km meant to circle Venus twice in about 14 days, dropping small probes as ballast. EVE's 2007 letter of intent, written by scientists outside ESA, cites that study for the balloon technologies it needed.

By 2010 the Russian timetable no longer fitted, with Venera-D then expected before 2020 and ESA's third medium-class launch (M3) set for 2022 to 2023, so the team, with Colin Wilson of Oxford as lead author, cut EVE to a single balloon. Submitted in December 2010, it would float at 55 km, where the air is about 25 °C at 0.5 bar, for at least ten days, long enough for one full circuit, and talk directly to Earth after a flyby carrier relayed its opening two hours. CNES ran a phase 0 study in 2010 and would have supplied the envelope and inflation system, with ESA providing the gondola and delivery; an orbiter from Russia or India was discussed. EVE did not reach the M3 shortlist, from which ESA picked PLATO on 19 February 2014 over EChO, LOFT, MarcoPolo-R and STE-QUEST.

The losing bids are visible in the missions that won. VOX's orbiter carried the VERITAS investigations, and VERITAS was chosen with DAVINCI on 2 June 2021; eight days later ESA selected EnVision. Those winners now face their own risk: the White House budget request for 2027 leaves out DAVINCI, VERITAS and the US radar for EnVision, which the Planetary Society reads as ending them, and as of 1 November 2026 Congress had not passed NASA's budget for that year. For Venus balloons, landers and aircraft that were studied but never entered in a competition, see Landers, balloons and rovers on the drawing board.