Thursday, January 22, 2009

Manned Venus Flyby

There have been many planned flyby missions for Mars and-or Venus. Much effort was put into these plans, in part because it was expected that Russia would skip the moon in the 1970s and chose a new target which would give them a chance to be first. A manned mission would be one of the best choices. Here is one of the lightest manned missions I have yet uncovered, and it would have been a fairly simple extension of the Skylab program. I think that this would have been good practice for eventual manned landings. Other proposals vary in size, most are large indeed calling for several Saturn V launches, often in rapid succession. This is the most likely to succeed, then simply because it would cost so little money. A mission like this would be fairly practical in the next decade if it were to use a modified ISS section, an Orion class CEV, and several large engines that could be fired in stages (a few 25,000 lbs storable propellant motors would probably do the job, probably 4 for venus and 7 for mars). Please check out the information below, and the images. These have been essentially pulled directly from the Wiki page, making me your rocketry middle man.

"The proposed mission would use a Saturn V to send three men to fly past Venus in a flight which would last approximately one year. The S-IVB stage would be a 'wet workshop' similar to Skylab, first using the S-IVB engine to launch the mission on course to Venus, and then vented of any remaining fuel to serve as home for the crew for the duration of the mission. The Apollo SM engine would be used for course corrections on the way to Venus and back to Earth, and for a braking burn before the Command Module re-entered Earth's atmosphere. In order to free up more space in the Spacecraft Lunar Module Adapter for the docking tunnel connecting the CSM to the S-IVB, the SPS engine on the Service Module would be replaced by two LEM engines, providing similar thrust with smaller nozzles.

Precursors to the Venus flyby would include an initial orbital test flight with an S-IVB 'wet workshop' and basic docking adapter, and a year-long test flight taking the S-IVB to a near-geostationary orbit around the Earth.

One oddity of the Venus flyby mission is that, unlike trips to the Moon, the CSM would separate and dock with the S-IVB stage before the S-IVB burn, so the astronauts would fly 'eyeballs-out', the thrust of the engine pushing them out of their seats rather than into them. This was required because there was only a short window for an abort burn by the CSM to return to Earth after a failure in the S-IVB, so all spacecraft systems needed to be operational and checked out before leaving the parking orbit around Earth to fly to Venus."

Most interesting to me, again, is the small number of components and booster launches needed for this mission, which would fly downhill towards the sun. The idea that an abort after ignition of the escape stage would be required within hours, adds a real taste of danger and excitement. Flyby missions are, after all, more about adventure and practice than science.

"interplanetary experience comes only from interplanetary missions: less difficult flights, such as that to Eros, could significantly enhance experience acquired in Earth orbital and lunar activities, and could thereby increase the probability of success for the missions to follow."   - Eugene Smith (Via Altair VI)

"Phase A

Phase A of the plan would have launched a 'wet workshop' S-IVB and a standard Block II Apollo CSM into orbit on a Saturn V. The crew would separate the CSM from the S-IVB by blowing off the SLA panels, then perform a Transposition and Docking maneuver similar to that conducted on the lunar flights, in order to dock with the docking module attached to the front of the S-IVB. Optionally they could then use the S-IVB engine to launch them into a high orbit before they vented any remaining fuel into space and entered the S-IVB fuel tanks to conduct experiments for a few weeks. After evaluating the use of the S-IVB as a long-term habitat for astronauts, they would separate the CSM from the S-IVB and return to Earth.

Phase B

Phase B would test the Venus flyby spacecraft in a long duration mission in high orbit. A Saturn V would launch a Block III CSM designed for long-term spaceflight and a modified S-IVB with the Environmental Support Module required for the real Venus flyby, and following the transposition and docking maneuver the S-IVB engine would carry the spacecraft to a circular orbit at an altitude of about 25,000 miles around the Earth. This altitude would be high enough to be clear of Earth's radiation belts while exposing the spacecraft to an environment similar to that of a trip to Venus, yet close enough to Earth that the astronauts could use the CSM to return in a few hours in an emergency.

Power would probably be provided by solar panels similar to those used on Skylab, as fuel cells would require a very large amount of fuel to operate for a year. Similarly the fuel cells in the SM used to provide power on lunar flights would be replaced by batteries which would provide enough power for the duration of launch and re-entry operations.

Phase C

Phase C would be the actual manned flyby, using a Block IV CSM and an updated version of the Venus flyby S-IVB which would carry a large radio antenna for communication with Earth and two or more small probes which would be released shortly before the flyby to enter the atmosphere of Venus. The Block IV CSM has LEM engines replacing the Service Propulsion System engines, batteries to replace the fuel cells, and other modifications to support long-range communication with Earth and the higher re-entry velocities required for the return trajectory compared to a return from lunar orbit.

The Phase C mission was planned to launch in late October or early November 1973, when the velocity requirements required to reach Venus and the duration of the resulting mission would be at their lowest. After a brief stay in Earth parking orbit to check out the spacecraft the crew would head for Venus: in the event of a major problem during the Trans-Venus Injection burn, they would have roughly an hour to separate the CSM from the S-IVB and use the SM engine to cancel out most of the velocity they gained from the burn. This would put them into a highly elliptical orbit which would typically bring them back to Earth for a re-entry two to three days later. Beyond that time the SM engine would not have enough fuel to bring the CSM back to Earth before the SM batteries ran out of power: it would literally be 'Venus or Bust'.

After a successful S-IVB burn, the spacecraft would pass approximately 3000 miles from the surface of Venus about four months later. The flyby velocity would be so high that the crew would only have a few hours for detailed study of the planet. At this point, one or more unmanned probe landers would separate from the main craft and land on Venus.

During the rest of the mission the crew would perform astronomical studies of the sun, the sky and Mercury, which they would approach within 0.3 Astronomical Units."

Many mars flyby missions carry a sample return probe that would either go directly to the earth (then using the manned craft only to carry the heavy mass at the same time, which is of dubious value), or better yet launch the sample back up to the flyby spacecraft where it could be stored or even studied during the boring flight home! Major concerns for any deep space mission, particularly a Venus mission (or a long mars landing) is radiation. The crew should have a safe house at the center of the craft, probably surrounded by propellants and-or water. Maybe food stores also? Radiation does not appear to be, however, severe enough to prevent these missions provided they are designed with some care.

Here is the source for this particular story, including lots of links at the bottom. Many of these have far more information. This is often the best part of a
Wiki entry. Also check out the Altair VI blog archives, there are several flyby missions in there.

Manned Venus Flyby


DTH Rocket said...

Wow! I never really saw it as being as simple as this before. Several months ago I wrote a twelve page book called "How to get to Mars and back in 12 easy steps." My mind was boggled by how much hardware it would take to land a crew of 2 or more on Mars and get them home safely. But a simple flyby mission would make so much more sense! I never realized how feasible that really is.

Thanks for the post.
~DTH Rocket

R2K said...

Indeed far quicker and cheaper, but at the same time the results are very different. A flyby is, in my mind, a very important step between apollo (yeah that program from the 1960s) and a mars landing (now sadly pushed back to "the 2030s" which might be ok for you DTH but at 26 I am already worried I wont live to see a mars landing).

We should have flown additional skylab missions, then moved on to these flyby missions in addition to getting to apollo 20 at the moon. Then we should have moved towards mars landings in the 1980s. All of these things could have been done, I am convinced, in the place of the space shuttle. Continued trips to mars would have used the cost of the ISS. Just horrendous planning.

The EGE said...

What about solar heating? It seems to me that being roughly 40% closer to the sun would get you several times the solar radiation, both heating and nasty particles traveling at relativistic velocities. Still, that sounds like a very cool - and possibly workable - idea.

R2K said...

Solar heating isnt a huge issue... you have highly reflective surfaces, and active cooling.

I would argue for artificial gravity on such a mission. They did not plan for it and you do not need it, but for the sake of sanitation and comfort, one would really appreciate a few fractions of a G, perhaps .1 G. This kind of slow rotation would also help balance solar heating.

Radiation is a big deal. Not during normal flight (though some shielding is always nice) conditions, but during powerful solar activity. There would have to be a "storm shelter". Water, food, supplies, these things should be stored around a small space that would be able to house the crew for a few days.

Again all research indicates that radiation is a concern, but not a show stopper.