#241 - Venus - Davinci+ - Michael Sekerak
Chris and Matt Discuss Venus and the missions that have been there so far, and Matt has the honour of interviewing Mike Sekerak Lead engineer of the Davinci+ Mission, recently chosen as the next discovery Mission by NASA
Fair Venus shines Even in the eve of day, with sweetest beam Propitious shines, and shakes a trembling flood Of softened radiance from her dewy locks.
Anna Letitia Barbauld (18th-century English writer)
NASA has selected the DAVINCI+ (Deep Atmosphere Venus Investigation of Noble-gases, Chemistry and Imaging +) mission as part of its Discovery program, and it will be the first spacecraft to enter the Venus atmosphere since NASA’s Pioneer Venus in 1978 and USSR’s Vega in 1985.
Interview with Michael J. Sekerak, PhD, Lucy Deputy Project Systems Engineer
Solar Electric Propulsion Systems Engineer @ NASA Goddard Space Flight Center. But he is also the Lead engineer on the latest mission to Venus announced last week, after a 30-year break NASA will return.
Venus is our sister planet, incredibly it may have been similar in temperature less than a billion years ago, but something happened and we don’t know what. There may have been shallow oceans about 715 million years ago. 30 miles up in the atmosphere there is a similar pressure and temperature to Earth so if life had taken hold maybe it retreated here?
Venus despite rhyming with the male anatomy is considered the female planet (named after the Roman god of Beauty), or the Russian planet.
The Russian’s really do have a claim on this too, they have absolutely gone to town at Venus.
Missions of note
America did the first successful mission with a Flyby of Venus on 14th December 1962 with Mariner 2. The first probe to have a planetary encounter.
Venera 4 (Russian for Venus 4) was the next successful mission, and returned atmospheric data on 18th October 1967, but was never intended to work when it reached the surface.
Mariner 5 a day later achieved another flyby measuring the atmosphere with radio occultation.
Venera 5 and Venera 6 entered the atmosphere on 16th and 17th May worked for almost an hour
Venera 7 15 December 1970 became the first soft landing on another planet, it rolled on the landing so the return of data was very limited, but again the first signal from another planet. Amazingly they thought the probe was silent, but Oleg Rzhiga, reviewed the tapes a few weeks later to find the tiny signal from the misaligned medium-gain antenna. 23 minutes of the signal.
It was found that the temperature at the surface of Venus was 475 °C (887 °F) ± 20 °CUsing the temperature, and models of the atmosphere, a pressure of 9.0 MPa (1,300 psi) ± 1.5 MPa was calculated. (about the same as half a mile deep in the ocean)
The parachute design was really cool, it opened more and more using a melting reefing line. However it did fail, so the probe hit the surface at 37 mph. From the spacecraft's rapid halt (from falling to stationary inside 0.2 seconds), it was possible to conclude that the craft had hit a solid surface with low levels of dust.
The probe provided information about the surface of Venus, which could not be seen through a thick veil of atmosphere. The spacecraft definitively confirmed that humans cannot survive on the surface of Venus, and excluded the possibility that there is any liquid water on Venus
Venera 8 landed much better in July 1972. The probe worked for about 50mins on the surface, Venera 8's photometer measurements showed for the first time that the Venusian clouds end at a high altitude, and the atmosphere was relatively clear from there down to the surface. The on-board gamma-ray spectrometer measured the uranium/thorium/potassium ratio of the surface rock, indicating it was similar to Alkali basalt
Venera 9 22nd October 1975 - and sent back the first images from the surface of any planet!!! Many of the instruments began working for 53 minutes and immediately after touchdown and the cameras were operational 2 minutes later. These instruments revealed a smooth surface with numerous stones. The lander measured a light level of 14,000 lux, similar to that of Earth in full daylight but no direct sunshine. During descent, heat dissipation and deceleration were accomplished sequentially by protective hemispheric shells, three parachutes, a disc-shaped drag brake, and a compressible, metal, doughnut-shaped landing cushion
A lens cap failed to deploy so the photo was not a full 360 panorama.
Vanera 10 3 days later, almost identical down to the lens cap not coming off.
Pioneer Venus 1 and 2 an orbiter and atmospheric craft, both successful in early December 1978. PV2 consisted of 4 atmospheric probes, 1 large and 3 small, all returning data as they floated through the Venusian atmosphere, no cameras and were not designed to survive the landing. Below the altitude of 50 km, the temperatures measured by the four probes are identical to within a few degrees. They are between 448 °C and 459 °C (838 °F and 858 °F) on the surface. The ground pressure is between 86.2 bar and 94.5 bar. Nephelometers identified three cloud layers with different characteristics. The most remarkable discovery was that the ratio of 36argon / 40argon isotopes much higher than in the atmosphere which seems to indicate that the genesis of the Venusian atmosphere is very different from that of Earth
The orbiter PV1 would stay in orbit throughout the 1980s and the early 1990s
Venera 11 and 12 Christmas 1978, were not quite as successful and failed to get pictures back.
Results reported included evidence of lightning and thunder, also the high Ar36/Ar40 ratio, and the discovery of carbon monoxide at low altitudes
Venera 13 - First recording of sounds from another planet 1st march 1982. A colour panorama, the fallen lens caps were mistaken as alien life by Leonid Ksanfomaliti. The Venera 13 lander appears in the short film Horses on Mars (2001) with a message to the main character who is a microbe lost on Venus. Venera 14 landed a few days later and also functioned on the surface for almost an hour. American researcher Don P. Mitchell has processed the colour images from Venera 13 and 14 using the raw original data. The new images are based on a more accurate linearization of the original 9-bit logarithmic pixel encoding. 2 years later Venera 15 and 16 were orbiters
So the Venera program established a number of precedents in space exploration,
First human-made devices to enter the atmosphere of another planet (Venera 3 on 1 March 1966),
First to make a soft landing on another planet (Venera 7 on 15 December 1970),
First to return images from another planet's surface (Venera 9 on 8 June 1975),
First to record sounds on another planet (Venera 13 on 30 October 1981), and the
First to perform high-resolution radar mapping scans (Venera 15 on 2 June 1983).
VeGa = Venus and Halley (Galleya) combined. After their encounters, the Vegas' motherships used the gravity of Venus, also known as a gravity assist, to intercept Halley's Comet
Vega 1 lander - Similar to the Veneras, 11 june 1985 - but no images as the landing site was at night. There was also a balloon,
The balloon package was pulled out of its compartment by parachute at 61 km altitude
A second parachute opened at an altitude of 55 km extracting the furled balloon.
The balloon was inflated 100 seconds later at 54 km and the parachute and inflation system were jettisoned.
The ballast was jettisoned when the balloon reached roughly 50 km and the balloon floated back to a stable height between 53 and 54 km some 15 to 25 minutes after entry.
The mean stable height was 53.6 km, with a pressure of 535 mbar and a temperature of 300–310 K in the middle, most active layer of the Venus three-tiered cloud system. The balloon drifted westward in the zonal wind flow with an average speed of about 69 m/s (248 km/hr) at nearly constant latitude.
The probe crossed the terminator from night to day at 12:20 UT on 12 June after traversing 8500 km.
The probe continued to operate in the daytime until the final transmission was received at 00:38 UT on 13 June from 8.1 N, 68.8 E after a total traverse distance of 11,600 km or about 30% of the circumference of the planet.
It is not known how much farther the balloon travelled after the final communication
Vega 2 happened about 3 days later with a very similar architecture.
Magellan was deployed by Atlantis in May 1989, a first, and entered orbit on 10th October 1990, Magellan was the fifth successful NASA mission to Venus, and it ended an eleven-year gap in U.S. interplanetary probe launches. the first spacecraft to test aerobraking as a method for circularizing its orbit. It mapped the surface of Venus by using synthetic-aperture radar and to measure the planetary gravitational field after 4 years in orbit.
Venus Express ESA achieved orbit april 2006, lasted till nov 2014, launched on a soyuz, main objective of the mission was the long term observation of the Venusian atmosphere. Venus Express was also used to observe signs of life on Earth from Venus orbit, Earth was less than one pixel in size, which mimics observations of Earth-sized planets in other planetary systems. These observations were then used to develop methods for habitability studies of exoplanets.
27 November 2007: The scientific journal Nature publishes a series of papers giving the initial findings. It finds evidence for past oceans. It confirms the presence of lightning on Venus and that it is more common on Venus than it is on Earth. It also reports the discovery that a huge double atmospheric vortex exists at the south pole of the planet
The only currently operational probe.
Akatsuki ("Dawn"), Venus Climate Orbiter (VCO) Japanese (JAXA) It was launched aboard an H-IIA 202 rocket on 20 May 2010 and failed to enter orbit around Venus on 6 December 2010. After the craft orbited the Sun for five years, engineers successfully placed it into an alternative Venusian elliptic orbit on 7 December 2015 by firing its attitude control thrusters for 20 minutes and made it the first Asian satellite orbiting Venus.
By using five different cameras working at several wavelengths, Akatsuki is studying the stratification of the atmosphere, atmospheric dynamics, and cloud physics.