It’s just about time I got back to describing the planets and our efforts to visit them. Today we do Venus the second planet from the sun named after the Roman Goddess of Love.
Detail from “The Birth of Venus” by Sandro Botticelli, 1486
Venus is hot – it’s the hottest planet as a matter of fact due to its thick mostly CO2 atmosphere. The pressure on the surface of Venus is like 92X the atmospheric pressure here on Earth so sending probes there has been challenging because the surface is around 860 degrees F – hot enough to melt lead! I mean think about a soldering iron; I usually set mine around 600 F and that just melts the heck out of solder which made of lead and tin. It’s hot on the surface of Venus.
Whereas the last planet we checked out, Mercury had the most elliptical orbit of any planet, Venus is the least elliptical orbit and is practically perfectly circular – but not quite. Perihelion is 107,477,000 km and aphelion is 108,939,000 km. It is almost the same size as Earth, just a little smaller at a diameter of 12,092 km, 650 km smaller than Earth. And it’s rocky with an atmosphere; but no magnetic field like Earth or Mercury.
Also, to fly there by space vehicle, it’s the closest planet to us. So we have gone there a bunch of times. The first successful interplanetary mission was Mariner 2 launched 1 March 1962 and it passed within 34,773 km of Venus on 14 December 1962.
Artist impression of Mariner 2, NASA
But on 1 March 1966, the first man-made object to strike the surface of another planet was the Russian made Venera 3.
Russian made Venera 3
It didn’t send back any data, because the electronics crapped out en-route – but the Russians are the first to hit another planet with something! And they kept trying and with Venera 7:
It entered the atmosphere of Venus on December 15, 1970. Unusually the lander remained attached to the interplanetary bus during the initial stages of atmospheric entry. This was to allow the bus to cool the lander to -8°C for as long as possible. The lander was ejected once atmospheric buffeting broke the interplanetary bus’s lock-on with Earth. The parachute opened at a height of 60 km and atmospheric testing began with results showing the atmosphere to be 97% carbon dioxide. During the descent the parachute appeared to fail, resulting in a more rapid than planned descent. As a result the lander struck the surface of Venus at about 16.5 metres per second (54 ft/s) at 05:37:10 UTC. Landing coordinates are 5°S 351°E.
The probe appeared to go silent on impact. However, recording tapes kept rolling. A few weeks later, upon a reviewing of the tapes, another 23 minutes of very weak signals were found on them. The spacecraft had landed on Venus and probably bounced onto its side upon impact, leaving the medium gain antenna not aimed correctly for strong signal transmission to Earth. The only data returned from the surface were temperature readings, which gave a temperature of 475 °C (887 °F).
When it landed on the Venusian surface, it became the first man-made spacecraft to land successfully on another planet, and to transmit data from there back to Earth.
Last Venera mission was number 16 in 1983 and they followed Venera with Vega 1 and 2 in 1984 where they landed balloons on Venus. We didn’t hear much about the Russian Venus missions – maybe they were mentioned in passing – but those were awesome missions. The Americans continued to explore Venus with the various Mariner missions, and two Pioneer Missions:
All told, I counted forty-six attempts at Venus by us Earthlings of various nationalities – not all of them successful but most were! http://en.wikipedia.org/wiki/Venus There’s a nice tabular layout of all the missions so far – you can count them!
There is talk at NASA of exploring Venus by way of airship – since the atmosphere is thick you could conceivably make a kind of dirigible with air as the lifting gas and at around 31 miles above the surface which is about where you’d end up, it’s pretty nice. Not too hot, not too cold… http://www.universetoday.com/117434/exploring-venus-by-airship-cool-concept-but-certainly-not-new/
Here’s a nice video:
There’s, of course, the usual naysayers, but I think it’s a cool idea.
Surface of Venus – NASA