A message from our CEO about the future of Stack Overflow and Stack Exchange. Read now.

# Tag Info

56

The reason is delta-v, which is a crucial concept in Spaceflight. It means change in velocity, and is the primary 'currency' that space mission have to expend in order to reach places in the solar system. On earth, if you want to go anywhere, you can get there at any speed, it just takes longer. Unfortunately, that is not how it works in space, because the ...

52

It takes surprisingly little delta-v to reach Venus for a flyby -- about 3850 m/s from LEO instead of the 3200 m/s or so required to get to the moon -- so while the payload would have to be reduced from the normal Apollo mission, it wouldn't have been impossible. For Apollo 17, if we consider the payload to be the CSM, LM, and LM adapter, the total is 48.6 ...

41

When will we send? We already did. In 1985 and 1986 the Soviet Union sent two Vega probes to Venus. Both included a robotic balloon (usually called aerobots). The two balloon aerobots were designed to float at 54 km from the surface, in the most active layer of the Venusian cloud system. The instrument pack had enough battery power for sixty hours of ...

35

We didn't know how hostile Venus's surface was, until we had landed there. The atmosphere of Venus makes it easier to land there than Mars. From Wikipedia, we learn: Before radio observations in the 1960s, many believed that Venus contained a lush, Earth-like environment. While there was some concept that Venus was hot, and had a high pressure, the exact ...

31

Why are people so fascinated about Mars and not about Venus at all? The trivial answer - Mars is moderate place. A human could easily get around with a spacesuit, and it is trivial for robots and equipment to exist on Mars. Venus is a swirling hell. The "atmosphere" is a sea of incredibly hot, ultra-boiling, 800+ F° sulfuric acid (!!!) (Indeed, Venus is ...

25

Buoyancy is a big problem. To stay aloft, the average density of the balloon envelope, lifting gas and gondola must be <= the density of the surrounding atmosphere. The pressure inside a balloon must be equal to or slightly greater than the surrounding atmosphere, otherwise the balloon will collapse. If you look at the ideal gas law you'll see that see ...

23

Based on saturation diving operations, it looks like the limits are as follows: Compressed air: Nitrogen narcosis limits you to around four times Earth's atmospheric pressure. Any gas mix: Hydreliox was used for the current depth record; insomnia and fatigue issues appear to limit you to around 65 times Earth's pressure regardless of gas mix. Neither Titan ...

22

There is one area of exploration on Earth that approximates conditions on Venus, namely that of deep oil and gas mining, and a few additional areas of technology, near avionics engines, and even auto engines. The stated goal for such electronics is to function at 200 C or higher. The most promising technology for surviving high temperatures is Silicon ...

22

Thanks to @MarkAddler for his search suggestions I've tried to balance length against completeness, and both lost here. However I have included enough material to try to be convincing that RTGs, singe-use storage batteries, and rechargable batteries for higher power events have all been investigated and solutions exist to provide at least the electrical ...

21

Nobody really knows for sure. And there's two, nay three more odd things about it's rotation on its own axis, namely: It is the only planet in the Solar system that rotates retrograde, i.e. clockwise, when all other planets rotate prograde, or anticlockwise, on their axes, Latest findings (merely a good month ago as of writing this answer) revealed that ...

20

An orbit has an angular momentum that is conserved. That angular momentum vector keeps the orbit at a fixed orientation in inertial space. As a planet orbits the Sun, the local time of the ascending node moves around the clock over that planet's year. The only way for an orbit to be Sun-synchronous is for there to be a torque applied to the orbit to ...

19

To some extent, we can answer the question for the tools currently available to life, using basic physical principles, and the answer to that is "no". This needs consideration of the atmosphere of Venus and the nature of photosynthesis. The goal of terraforming would primarily be to sequester (or "lock away") the extra atmosphere. So we mainly need to ...

19

The pressure exerted on a surface area under the ideal gas law is $P = \frac{\rho k_B T}{\mu}$ with the following notation: $\rho$ being the volume mass density (or simply density) $k_B$ is the Boltzmann constant $T$ is the temperature in Kelvin $\mu$ is the mean molecular mass in g/mol On Earth $\mu_E \approx 29$, while on Venus it is $\mu_V \approx 44$. ...

18

The mass of Mars is so small, and its magnetic field so weak that it cannot hold onto carbon for a long period of time, making almost all of it to escape. (Venus and Earth are close to identical in size, Mars is much smaller) Venus does not really leak that much of its atmosphere, the only noticeable exception is that all hydrogen compounds are virtually ...

18

One picture is worth all your base to us. Before we sent probes to Venus we had no pictures of its surface. Whether it lands or not you have to penetrate the atmosphere of Venus to take pictures of it, whereas the surface of Mars can be easily seen through its weak atmosphere from afar. Most of the information about Venus has been derived from the ...

18

No, because thermonuclear weapons don't make holes in clouds, they make clouds. First you have a fireball: And then you get a big mushroom cloud: Neither the fireball or mushroom cloud are see-through. Even if the bomb managed to push Venus' thick atmosphere out of the way all you'd see is fireball and mushroom cloud before it closed right back up again ...

18

Question: Why not bring cyanobacteria and fertilizer to the atmosphere of Venus to improve conditions for life there by producing oxygen ? ... Only a few scientists have speculated that thermoacidophilic extremophile microorganims might exist in the lower-temperature, acidic upper layers of the Venusian atmosphere. It has been speculated that the ...

16

According to Wikipedia launch windows to Venus occur every 19 months. In some cases multiple successful probes were launched with the same design at the same time so I'll group those together (the Soviets launched two similar/identical missions per launch window they actually used to ensure mission success through redundancy). I'll label each mission with ...

16

The simple answer is that taken as a whole the Venera missions didn't land particularly close together. Starting with Venera 4: The overall spread of Venera landing sites (when you include the probes that didn't survive to the surface) is nearly 110° of longitude. For comparison, the spread of Luna landing sides on the map you provided of the moon is ...

14

I'm going to only start calculating delta v from Earth Escape, using this Delta V table. Furthermore, I'll assume we are starting from LEO, and we want to get in to a low orbit of the appropriate planet. The numbers turn out to be: Venus- 3.5 km/s to Venus, 3.3 km/s to Low Venus Orbit Mars- 3.6 km/s to Mars, 2.1 km/s to Low Mars Orbit. Bottom line is, it ...

14

It's more a question of semantics, rather than a physical reality. An ocean would probably be thought to have a clearly defined surface. On the other hand, terminal velocity is only about 5m/s, which is a moderate running speed (Usain Bolt does 10 m/s). This gives you an idea about how thick the gas really is. In fact, one of the Pioneer Venus probes kept ...

13

No, there is no space race to Mars. The original space race was to orbit, for entirely military reasons. Sputnik was simply a demonstration of "we can drop a nuke anywhere we want, any time". The second space race to the Moon was a publicity exercise. It served no military purpose, and it didn't serve any scientific purpose either. (Science builds off ...

13

The early Venera probe hulls were designed for an atmospheric pressure of 25 bar. Barometers were designed for 10 bar. This was in line with what was then assumed to be the surface conditions. At the time, it was thought that the surface temperature of Venus was approximately 300C, with an atmosphere consisting mainly of carbon dioxide and nitrogen at ...

12

The key thing to doing this is to accelerate some of the mass of Venus outside of the planet, or alternatively bringing in some mass. Thus, there are 2 main things that could be done to alter the rotation speed. These ideas are explained in Wikipedia. Carefully plan a series of asteroid impacts in a direction where they can increase the rotational energy of ...

12

There's a lot to be said about circulation of Venusian troposphere first, but that's all nicely explained on Wikipedia. But please read it as background, if that's required; For easier reference though, and from that same Wikipedia page, here's a cross-section diagram of the atmospheric circulation in the atmosphere of Venus: An aerostat colony in Venusian ...

12

An RTG certainly can and would work on Venus, since the hot side is about 1200 C. It just wouldn't be as efficient as it would be with a colder cold side. Search for papers by Geoff Landis on this.

12

Note: @Conelisinspace's comment reminds me that the clouds don't begin at the surface. Double checking the plot, this happens at roughly ~30 km, at which point the pressure is almost 10x lower, but the (absolute) temperature drops by almost a factor of 2 as well, so we can't quite say we're above 90% of the mass. However, even if we could, the temperature ...

12

A Venus flyby does little to nothing towards the stated goal: a manned landing on Mars. because you get a lot closer to the Sun than on a Mars mission, you need to modify the spacecraft to reject all that extra heat. There goes the commonality in the spacecraft. A flight time of 5 months vs. 6 months (one way) for a Mars mission is not a significant ...

11

We have plenty of metallic materials that could stand the heat of Venus's atmosphere, including copper, nickel, cobalt, iron, titanium, tungsten, and chromium, to name but a few (here's a list of elemental melting points), as well as a large number of alloys including carbon steel and stainless steel. Even the sulfuric acid isn't a huge problem with some of ...

Only top voted, non community-wiki answers of a minimum length are eligible