One site I read said that the launch date is dictated by a once-every-fifteen-years opportunity to flyby and return with minimum delta-V. Since the synodic period of Earth/Mars is about 779 days, what other factors are in play here?
Although the synodic period (the period for which the Mars makes closest approach to Earth, or alternately makes the same relative conjunction) is ~780 days, you also have to consider the phasing of the mean anomaly and the differential inclination to the Laplace plane (1.58° for Earth, 1.67° for Mars) if you truly want to minimize the enery required to rendezvous. 0.09° may not sound like much out of plane difference to cover, but at planetary speeds and distances that still works out to an additional delta-V requirement of around 0.5 km/s; about the same as was required by the Apollo CSM to circularize into Lunar orbit. This is in addition to any impulse reqiurements to achieve Mars planar orbit (~10 km/s). So if you are straining the payload capacity of your launch and transorbital injection vehicle (as many Delta II-launched missions commonly did) that amount of additional required budget may break you.
Stranger
For a more realistic goal, see http://goldenspikecompany.com/
Thier goal is offering moon missions to countries who can’t do it on thier own (basically)
Brian
Their entire business model appears to be centered around space tourism and sale of novelties to space enthusiansts. Aside from a handful of dot.com tycoons there doesn’t seem to be the multi-billion dollar demand that would be required to sustain such an industry.
For private industry to develop fiscally viable commercial spaceflight (not for flush DoD customers or susidized by government agencies) it has so have some objective that provides a unique service that cannot be achieved by terrestrial operations, e.g. telecommunications, space surveillance, asteroid mining of rare elements, et cetera. Going to the Moon just to say we’ve been there was sufficient to open the national checkbook for the Apollo program during the Cold War, but that show doesn’t play today, and there isn’t enough science budget for Moon geology research in every university in the country combined to pay even a fraction of the cost of a manned Lunar mission, much less sustain a company.
There are economic opportunities in space, but not against the premium of carrying people around, any more than it would be worthwhile to send a photographer up in an orbiting capsule to map the Earth versus a satelite doing the same job.
Stranger
Did you miss the bit where they’re sending a married couple?
I may have misunderstood it, but I got the impression that somehow the launch date was critical for being able to gravity-boost past Mars to a return-to-earth trajectory without having to burn fuel (or at least very little). Is that correct?
Given that the spacecraft will be moving with essentially the save velocity vector as Mars at the point of intercept, there is almost no ability to use any kind of swing-by maneuver to accelerate the vehicle (at least, on interplanetary speeds, although more modest adjustments can be made within the planets sphere of influence as done by the Cassini spacecraft in the Saturnian system). Gravity assist requires a relatively high differential in velocity in order to achieve significant impulse transfer. A low energy transit to Mars and back, however, seeks to minimize delta-V changes, as it has to ‘stop’ (inject into orbit around Mars) and then start (injection to the return trajectory) approximately 262 days later. There are other “cycler” orbits occuring at synodic periods which are faster but require higher injection delta-V requirements, and are therefore not minimum energy.
Stranger
But the barebones mission wasn’t going into an actual repeated orbit around Mars, was it? I thought it was one pass, curving around past the planet and back to Earth. Is that even possible?
Chalk me up as another fan of a voluntary 1-way mission to Mars. Send enough crap with them to give them a fighting chance to make it for several years… and give them a couple cyanide capsules as well.
Sure, it is possible. It is also pointless. We can send objects to Mars; we’ve done so in the past. Sending an object with a couple of bodies in it isn’t terribly more impressive.
Seriously? Other than well deserved outrage from multiple quarters, what would that possibly achieve? The whole “Let’s send people because it will inspire the public about space,” is vastly overstated and demonstatably not sustainable. Armstrong and Aldrin had barely returned from the Moon when Apollo budgets were slashed and the cameras were turned off. NASA couldn’t even get funding to assemble and launch the remaining functional flight sets of the Saturn V rocket. After the first STS launch the public lost interest until the catastrophic loss of Challenger.
The general public could give fuck-all about science or space exploration, and sending a couple of people out to do nothing but die on another planet isn’t going to change that. A sustainable presence in space–and eventually, habitation and manned exploration–are predicated on getting something out of the effort that is useful to the public as a whole, and making such efforts self-sustaining.
Stranger
The proposed mission is indeed a no-orbital insertion flyby:
And not completely pointless: it would be the first manned interplanetary mission and could serve as a practice run for a more ambitious mission.
Thanks for this. Someone was discussing it on LinkedIn, and I had no idea what they were talking about.
In a space station, with room for exercise equipment and a large infrastructure on Earth providing resupply.
Understand the challenge of sitting in microgravity for extended periods is that the human body quickly begins to adjust to the lack of gravity loading. Muscles begin to atrophy. Bones begin to leach calcium and minerals into the bloodstream and weaken.
What the astronauts do to fight this includes a regimen of excercise including cardio, “weight lifting”, and running on a treadmill. These exercises are designed from the best dataset we have to prevent bone loss and muscle atrophy, so when the person comes home, they can actually walk and not collapse with a heart attack, not be a bedridden weakling, and not have bones ready to fracture just by regular moving around, nevermind by accidental falls (which are far more likely because the muscles are weaker).
There’s another element that is not well known, the vestibular system and the visual coordination. It has been shown that lack of practice can actually affect coordination and balance with respect to visual tracking and vestibular response. Don’t walk or run, lose ability to balance when trying to walk and run.
The current exercise equipment for ISS consists of a treadmill system (actually 2 different ones, one in the US side one in the Russian Service Module), an excercise bike apparatus, and a weight-lifting replacement system using resistance instead of gravity. Each of these requires a certain amount of space for the hardware and empty space for the person using the equipment. While empty space is reusable, hardware space is not.
In particular, the current weight lifting simulator (ARED) is a spacehog, takes up as much room as a refrigerator.
Of course the crew could just sit in their Apollo-sized capsule seats the entire 501 days, and return effectively 2 decades older with respect to bone loss, muscle loss, and balance issues.
Shit happens. Earth is a forgiving environment compared to space. You can’t just open the windows if something happens to the air conditioner.
Link to specific article.
A manned mission to Mars won’t be possible until we have nuclear propelled spacecraft…this will reduce the travel time to Mars , to less than a month. If we wanted, we could mount a Werner Von Braun-style multi-ship/multi year mission, but that would be beyond the capabilities of any private entity.
Wold it be nice? Yes…worth the cost-no.