The International Space Station residents were back at work Thursday after an ammonia leak indication sent the crew over to the Russian segment. Flight controllers determined there was no leak and NASA managers allowed the crew to resume normal activities and open the U.S. segment back up.
This week, the orbital residents kicked off several new experiments delivered Monday morning aboard the SpaceX Dragon commercial cargo craft. Italian astronaut Samantha Cristoforetti worked in Japan’s Kib [...]
There could be at least two unknown planets hidden well beyond Pluto, whose gravitational influence determines the orbits and strange distribution of objects observed beyond Neptune. This has been revealed by numerical calculations made by researchers at the Complutense University of Madrid and the University of Cambridge. If confirmed, this hypothesis would revolutionise solar system models.
Astronomers have spent decades debating whether some dark trans-Plutonian planet remains to be discov [...]
Inner planets Venus and Mercury can never wander far from the Sun in Earth's sky. This week you've probably seen them both gathered near the western horizon just after sunset, a close conjunction of bright celestial beacons in the fading twilight. The pair are framed in this early evening skyview captured on January 13 from the ruins of Szarvasko Castle in northwestern Hungary.
Above the silhouette of the landscape's prominent volcanic hill Venus is much the brighter, separated from Mercury [...]
As governments and corporations continue to engage space security, commerce, exploration and colonization, the Christian Church will not be far behind. Historically the Church has always been part of the first waves of explorers and colonizers, with its ideological interests being easily supported by generous resources and strong infrastructures. The exploring Church has not always been a friendly guest, however, and at times has initiated or condoned great harm. This paper offers a beginning framework as one way of insuring an appropriate presence in space for the Church. This framework is built with three common religious planks, namely, theology, ecclesiology and church worker vocation. Each of these is recast in terms of the off-planet scenario. This paper concludes that an appropriate off-planet Church will be founded on an "exomissiological" theology, will embrace an ecclesiology that emphasizes religious health, and will adequately select, train and monitor its off-planet church workers.
Frequently I wish I could afford to have a personal orbital dynamics minion that I could have run analyses for me whenever I have a complex orbital dynamics question and would like to test my intuition. Unfortunately, Altius isn’t successful enough yet for me to afford that luxury, and while we have friends and advisors with the relative skills, I don’t have enough money to have them run every analysis I’m interested in. So I figured maybe I could toss this out as a potentially useful topic for someone’s PhD dissertation instead.
Short version: I’d like to do an analysis to see how hard it is (in delta-V, travel time, and launch window frequency) to get from one NEO to another, versus going from a NEO to a planet and back.
I’ve got a lot of friends (bless their hearts) who like to turn up their nose at poor benighted planetary chauvinists, and who go on and on about “once you’re out of a gravity well, why would you want to go back into one?” My intuition suggests they may be wrong, but I’d like to see numbers to either back up my opinion, or shoot it down. My intuition suggests that without atmospheres or the Oberth effect, you’re going to pay big delta-V penalties at each end of the trip, unless the synodic periods are really really long.
My thoughts on how to run the analysis:
Before you start, pick some subset of the NEO population above a certain size (say 100m diameter, or maybe 1km depending on available computing resources). Gather ephemeri for all of them.
Pick a random NEO in that group.
Depending on computing resources pick some specific number of other asteroids to analyze (say 50 or 100 or 1000), and randomly select them from the population.
Calculate pork-chop plots for travel from the initial asteroid to the other asteroid, and then back again.
Automatically extract from the pork-chop plots say the minimum delta-V for both legs of the trip, and the associated trip times, stay times, and estimated revisit frequency.
Run steps 4 and 5 using the Earth, Mars, and Venus as destinations, both with and without aerocapture/aerobraking at the planet end.
Repeat steps 3-6 a bunch of times (say 100 or 1000 times depending on how much parallel computing capability you have, and how thorough you want to be).
Analyze the data.
My hunch says that especially if you have aerocapture, you’re going to find that most of the time it’s easier for a given NEO to regularly “trade” with planets than it is with other NEOs, because you can both take advantage of the Oberth effect on departures from the planets, and you can take advantage of aerocapture on the way in. But I’d love to see someone run the numbers–I could be completely wrong.
An analysis like this would be really useful for figuring out what trade networks might look like in the future between NEOs and other solar system entities. If it turns out it’s much harder to get from one NEO to another on a regular basis, as my intuition suggests, it would suggest planets may remain the trade hubs with NEOs being more mining bases. If my hunch is wrong, maybe I owe my NEO-chauvinist friends an apology.
Bonus points if you can run the analysis using both high-thrust impulsive maneuvers as well as low-thrust, high-Isp maneuvers (like Solar Electric Propulsion systems can provide), to see if SEPs noticeably change the equation–I really have no intuition on how realistic SEPs change or don’t change the equation for NEO transportation.
For the past half century the Drake Equation and the Fermi Paradox have provided the intellectual foundation for investigating the possible existence of extraterrestrial intelligence. But both the Equation and the Paradox are flawed and of questionable scientific utility. A replacement needs to be found, based on a different principle, and a parameter space for extraterrestrial intelligence is proposed as an improved tool of thought. This generates six distinct scenarios, whose implications for SETI are discussed.
Robotic spacecraft have been our primary means of exploring the Universe for over 50 years. Should interstellar travel become reality it seems unlikely that humankind will stop using robotic probes. These probes will be able to replicate themselves ad infinitum by extracting raw materials from the space resources around them and reconfiguring them into replicas of themselves, using technology such as 3D printing. This will create a colonising wave of probes across the Galaxy. However, such probes could have negative as well as positive consequences and it is incumbent upon us to factor self-replicating probes into our interstellar philosophies and to take responsibility for their actions.
Interstellar exploration will advance human knowledge and culture in multiple ways. Scientifically, it will advance our understanding of the interstellar medium, stellar astrophysics, planetary science and astrobiology. In addition, significant societal and cultural benefits will result from a programme of interstellar exploration and colonisation. Most important will be the cultural stimuli resulting from expanding the horizons of human experience, and increased opportunities for the spread and diversification of life and culture through the Galaxy. Ultimately, a programme of interstellar exploration may be the only way for human (and post-human) societies to avoid the intellectual stagnation predicted for the `end of history'.
A review of conceptual interstellar generation ships is followed by a presentation of optical and thermal properties of graphene and a discussion of kinematics/thermal-aspects of the solar-acceleration phase of a starship propelled by a graphene hollowbody solar-photon sail. The spacecraft departs from an initially parabolic solar orbit and the sail is oriented normal to the Sun during solar-acceleration. Perihelion is constrained to 0.1 AU because humans can tolerate ~3g for several hours without lasting effects. The 5 × 106 kg payload mass and 9.16 × 106 kg sail mass are applied as cosmic-ray shielding for the ship's 20-50 person population during the ~1,400-year cruise phase. Artificial gravity, the Coriolis Effect, closed-environment agriculture, illumination, on-board energy requirements, thermal dissipation, and hygiene/recreation are considered in a discussion of habitat design. Many concepts for mid-course trajectory correction are discussed including a new one that expels mass collected by a Cassenti toroidal ion scoop in a direction normal to the ship's trajectory. Although acceleration is affected by the unfurled sail, other options are discussed, as is the problem of protection from interstellar-dust erosion. As well as presenting the total mass budget, the conclusion reviews published variations and modifications on the generation-ship theme.
The Optical Search for Extraterrestrial Intelligence (OSETI) attempts to detect collimated, narrow-band pulses of electromagnetic radiation. These pulses may either consist of signals intentionally directed at the Earth, or signals between two star systems with a vector that unintentionally intersects the Solar System, allowing Earth to intercept the communication. But should we expect to be able to intercept these unintentional signals? And what constraints can we place upon the frequency of intelligent civilisations if we do? We carry out Monte Carlo Realisation simulations of interstellar communications between civilisations in the Galactic Habitable Zone (GHZ) using collimated beams. We measure the frequency with which beams between two stars are intercepted by a third. The interception rate increases linearly with the fraction of communicating civilisations, and as the cube of the beam opening angle, which is somewhat stronger than theoretical expectations, which we argue is due to the geometry of the GHZ. We find that for an annular GHZ containing 10,000 civilisations, intersections are unlikely unless the beams are relatively uncollimated. These results indicate that optical SETI is more likely to find signals deliberately directed at the Earth than accidentally intercepting collimated communications. Equally, civilisations wishing to establish a network of communicating species may use weakly collimated beams to build up the network through interception, if they are willing to pay a cost penalty that is lower than that meted by fully isotropic beacons. Future SETI searches should consider the possibility that communicating civilisations will attempt to strike a balance between optimising costs and encouraging contact between civilisations, and look for weakly collimated pulses as well as narrow-beam pulses directed deliberately at the Earth.
The concept of a long-term, open ended project like the starship raises questions about why the human race should engage in such an endeavour. Thinking about such a project inevitably means considering the effects of change not only in our technology, but also in our understanding of the world and even to ourselves. Project Daedalus was carried out in a time before the "Modern Age" with its instant communication, availability of information and massive computing resources, and the change is continuing. Considerations of possible encounters with extraterrestrials and even our evolution into "post-human" societies constrain us not to think about the future of an interstellar humanity but the future of creative consciousness.
The crew opened the hatch to the U.S. segment and returned inside at 2:05 p.m. Central time. Wearing protective masks, Virts and Cristoforetti sampled the cabin atmosphere and reported no indications of any ammonia.
The International Space Station mission management team, including all of the station Partners, met this afternoon and directed the station’s residents to return to the U.S. segment of the complex before the end of the day, systems permitting. The decision was made hours after t [...]
The six-member Expedition 42 crew is safe in the Russian segment of the International Space Station after an alarm went off in the U.S. segment of the orbital laboratory Wednesday morning.
Flight controllers are seeing no direct evidence of an ammonia leak and are exploring the likelihood a faulty sensor or computer relay set off the alarm.
NASA’s International Space Station Program Manager Mike Suffredini sat down with Public Affairs Officer Dan Huot to discuss today’s events. Suf [...]