68

According to Wikipedia, Voyager 2's launch window was a once in 175 year opportunity - the planetary alignments allowing a visit to Jupiter, Saturn, Neptune and Uranus. Adding more planets to a Grand Tour alignments would make them rarer.


27

Comet West with its unpredictable but estimated at 558 000 years period is a good contender. Since launch windows can aim for the alignment of N objects, the answer obviously tend to infinity. You also need to remember than launch windows are just "optimal launch times" Using non Hohmann transfers, or long parking orbits, you can launch any time (using ...


24

First order analysis Given that we have practical ion thrusters, it's time to look at them. Deep Space 1 The DS1 probe massed 387kg, had 83kg of fuel, operated for 162 days, and generated 92mN. So, it generated about 0.2mm/s^2. The craft is not tanks-dry, either. It has approximately 6 months (180 days) of fuel per design. That's a roughly 20% fuel ...


22

Sometimes you don't want to hibernate the craft, because it has scientific operations to perform during the interplanetary transfer phases. But even when you don't: Deep space hibernation is risky. There is always the risk that the wake-up procedure - whether triggered by the vessel or by the ground station - won't work and the vessel will not recover. It ...


21

Edit as of August 31, 2015: Looks like 2014 MU69 will be the post Pluto target. Paul Gilster has a nice article on Centauri Dreams. Edit as of Jan. 3, 2015: This article says 3 potential candidates were found in December of 2014. This article says the New Horizons team is running out of time to find KBOs to check out after it passes Pluto. No post Pluto ...


21

Feel free to edit this answer to add more or adjust formatting. List may be incomplete. Ordered by launch date: Hayabusa 2 and MASCOT to 162173 Ryugu, Japan/Germany/France, launched 2014, landed four rovers in 2018, currently surveying, Hayabusa 2 will depart December 2019 and return to Earth December 2020 OSIRIS-REx to 101955 Bennu, USA, launched 2016, ...


19

Hohmann launch windows occur each synodic period. Or a more general version of a Hohmann transfer would be a transfer orbit tangent to both departure and destination orbits. This also occurs each synodic period plus or minus. Call period of departure orbit T1. Call orbital period of destination orbit T2. Synodic period = |(T1*T2)/(T1-T2)| So for example ...


18

It wouldn't be at all. Let's look at it in a couple of different ways: The delta v required is 5.93 km/s. That's not quite, but a similar level of difficulty as launching the station in the first place! Landing either the Shuttle or the ISS on the moon would be difficult. They just weren't meant for it! There might be some parts that are usable, but in ...


17

Possible US based future stations Bigelow Aerospace, has launched two pathfinder station models (Genesis I in 2006 and Genesis II in 2007). I think they are both still in orbit, not active. They licensed the Transhab technology from NASA and ran with it. The pathfinder modules were not human habitable. They have primarily been waiting for someone to be ...


16

Considering that Voyager 1 is already 126 AU from the Sun 36 years since launch, there should be no reason that it would not be possible energetically using a normal launch, small maneuvers, and planetary flybys. Just a Jupiter flyby should be sufficient. Jupiter will also provide the necessary change in inclination. Designing a probe that is assured to ...


15

You are forgetting Pioneer 10, Pioneer 11, and New Horizons. Pioneers 10 and 11 respectively operated for 28 years and 16 years after completing their primary missions. New Horizons, which has yet to perform its primary mission (Pluto flyby in July 2015) or secondary mission (TBD flyby of a Kuiper belt object) will reach the heliopause in about 2047. No ...


13

Per https://standards.nasa.gov/documents/viewdoc/3315318/3315318 . NASA Policy Directive COMPLIANCE IS MANDATORY NPD 1210.1G Effective Date: April 28, 2010 Subject: Acceptance and Use of Monetary Gifts and Donations Responsible Office: Office of the Chief Financial Officer POLICY The National Aeronautics and Space Administration (NASA) may accept and ...


13

The launch of New Horizons was very critical. The NASA scientists had 5 years to develop a space probe to Pluto and make sure it got a gravity assist through Jupiter, which is only possible if launched in the year 2005 to 2006: although they had 5 years of time to prepare and launch, they faced several problems fixing the Atlas 5 rocket, budget issues, ...


12

A colleague worked on the Titan Mare Explorer (the concept did not proceed beyond proposal stage). It was an ultra-cool idea that would include to lower a boat to sail the seas of Titan (doesn't that sound catchy?). Alas, it wasn't selected; instead, NASA selected the InSight Mars lander — NASA keep changing their priorities as to where they want to go. ...


11

Currently the US has a policy against participating with China in any space endeavors ("Due to U.S. obstruction, China now can only have limited international exchanges and cooperation on space technologies and activities." [1]) Elon Musk says that SpaceX could provide manned transport in 2016, a year early of NASA's plans. [2] This does leave 2015 as a ...


10

Your question touches on several factors that influence the length of a mission: Mission preparation time Flyby versus orbital missions Transit time Mission preparation time You're trying to apply the rapid advances in mass-produced computing to other fields. Yes, if you wait five years, computers will be much faster. But Moore's Law is an exception: ...


10

There are entities that hope to mine asteroids, Planetary Resources and Deep Space Industries. The proposed Asteroid Retrieval Mission is based upon the Keck Report, a paper outlining how a small Near Earth Asteroid (NEA) could be parked in lunar orbit. Co-authors of the Keck Report include Chris Lewicki (Chief engineer of Planetary Resources), J. S. ...


10

An interstellar mission does not need to visit more than two planets, since your interest by definition lies in objects beyond the Solar System. The Voyagers were first and foremost planetary exploration craft, albeit with symbolic messages to alien civilizations. As I wrote in an answer to another question, the best trajectory (a.k.a. the Krafft Arnold ...


10

The Russian medical monitoring of long term flight participants was not considered well done by the rest of the worlds medical establishment. The ISS has much more equipment, resources, and crew time to monitor than did Mir (Crew of 6 vs 3). This is a repeat with a larger (2 vs 1, yay!) sample set with better monitoring in place, using lessons learned ...


9

There's this proposal floated by Boeing: http://en.wikipedia.org/wiki/Exploration_Gateway_Platform And Russia has had some similar plans, although it was for a station in lunar orbit: http://www.russianspaceweb.com/los.html The Boeing proposal would use some structural elements left over from ISS construction, while also including modules similar to those ...


9

NASA's New Frontiers program has been calling for a Venus lander (Venus In Situ Explorer) on every solicitation. Venus landers are proposed every time, sometimes making it to Step 2 in the competition (e.g. SAGE), but a Venus lander has not been selected yet. Maybe next time. There are color images of the surface of Venus from Venera. I'm not sure what "...


9

"We should wait for all the problems on earth to be solved before going into space". I've seen this sentiment multiple times, and I disagree vehemently. 1. There are other much more worthy targets of this kind of argument Whenever a space mission has cost overruns in the billions, I convert the dollar amount into B-2 bomber equivalents. That is, 2 billion ...


8

The US plan is to buy launches for LEO, and develop its own capsule and launcher for harder missions. The options are Soyuz to the ISS, and if any of them work; SpaceX's Dragon, Boeing's CST-100, and SNC's Dream Chaser. With the COTS program, NASA solicited commercial offerings to provide cargo to the space station, trying to wean itself from reliance on ...


8

There are multiple plans for new space stations. Bigelow Aerospace plans on completing their next-gen commercial space station by 2014. However, the future of space stations lies with the Chinese who plan to build on the success of the Tiangong-1 with the Tiangong-2 and the Tiangon-3 with the expectation of large manned station by 2020. This is ...


8

The Russian Venera missions 9 (1975), 10 (1975), 13 (1982), and 14 (1982) all took images of the Venusian surface. Venera 13 and 14 took color images. Russia is also planning another Venera mission called Venera-D. It was initially proposed in 2003, but the initial proposal has gone through several changes. The plan is currently much smaller than it was ...


8

Getting back is not impossible, just very expensive. This site has a good explanation of the phenomenon.


7

The concept was not a glider, but powered. It used storable biprop propellant rocket thrusters to fly at best for 81 minutes at 140 m/s. That comes out to a 680 km flight. With margins applied for mass growth during development, the range would be at or above the science requirement of 500 km. Once the propellant runs out, then it is a glider, but not ...


7

Above are 4 ellipses. They all have a 400 km altitude perigee, but widely varying apogees. The blue ellipse has an ~1.5 million km apogee, about the distance to SEL1 or SEL2. The larger grey ellipse has an apogee at EML2 altitude, the smaller grey ellipse has an apogee at lunar altitude. The red ellipse has an apogee at EML1 altitude. A striking thing ...


7

Well, they prepared by writing a speech text for Nixon "In event of Moon disaster". The opportunities to "fix a problem" aren't that many in space. At least no one can hear them scream. And fewer than 20 out of 540+ have perished in space. The blackness is not as dangerous as it looks, when approached with care. When the space shuttle Columbia failed, NASA ...


7

It's a late answer but I was surprised nobody cited this: Titan Mare Explorer (TiME) The TiME lander was a part of cooperative NASA-ESA mission TSSM. The mission was not considered as highest priority by Planetary Decadal Survey 2013 so it's not being implemented now. Also it was studied as standalone Discovery class mission. ASRG generator was planned as ...


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