Why? The challenge is primarily to land not to gather science. A primary ship reliant on a second simply doubles the cost and failure points. Fuel transfer in space is … I don’t think it’s ever been done and it certainly has never been done on an interplanetary transfer.
Searching for signs of life on Mars is almost certainly better done by remotely operated probes and rovers, because while we can reduce microbiological contamination on robotic vehicles to a bare minimum via thorough sterilization and clean handling technics, whereas it is essentially impossible to sterilize a crewed mission because of the sheer amount of microbiotic life climbing on and inside the human body that gets all over everything else in a short period regardless of precautions.
Sending two or more simultaneous missions to Mars has merit, albeit not for the reasons or scheme you state. As Grey notes, the transfer of bulk propellant between vehicles is well beyond the current state of the art and will be extremely challenging in freefall. (I have done considerable work on the issue and while there are several proposed methods none of them have been validated by even a limited engineering proof-of-concept, notwithstanding mitigation of hazard should propellants leak, freeze, or otherwise not behave as expected.) Sending multiple missions would allow for more flexibility in planning in selecting multiple landing sites and/or backup mission capability for a given launch window. The issues are cost and the ability to loft payloads into an interplanetary injection orbit almost simultaneously.
As for life on Mars, if it ever existed it is almost certainly microbal and buried well below the surface. Mars seems like the most “Earth-like” of planets in the solar system but it is really not much more hospitable to the development of actual life than the Moon. I personally do not have a lot of optimism about finding life on Mars, but I would give even odds for finding it potentially life-like non-equilibrium thermodynamic systems on at least one of the Jovian and Saturian moons (Titan, Europa, or Enceladus). I qualify the systems as being “life-like” because they may look nothing like organisms as we think of them but still fulfill the necessary qualifications for living organisms. So, if we really want to focus on looking for life, sending missions to the moon systems of Jupiter and Saturn is likely the best bet.
Stranger
If the mission is to search for signs of life, another strong argument for robotic probes is the number of them that can be sent for the same cost as a manned mission (ratio may exceed 100:1). Large numbers of relatively inexpensive probes could visit many different areas, whereas a manned mission’s range of operation would necessarily be restricted.
I will start to advocate for private space missions when one of them puts a person into orbit and lands them safely.
I got a great deal of hatred from believers when I said this on another forum. That was at least five years ago. I’m still waiting. I bet I’ll still be waiting in 2018.
Reminds me of a story I heard (don’t know the accuracy) about Walt Disney.
When he wanted something done (like animatronics that had not been invented yet), he WANTED IT DONE. If someone came to him with the 12 reasons why his request was simply impossible, Disney listened patiently, and then fired him. Then he got someone who said “this will be really really hard, and I’ll need more people and money”. And got it done.
Why would this goal be important for anything rather than a stunt? We can do so much with unmanned vehicles and probes - they can be of far, far more use than manned missions, which (I think) are somewhat akin to Evil Knevil jumping over canyons.
Yeah, that’s a really weird requirement. Manned flight should be pretty far down the list when it comes to the things that private companies do well. The first thing you want is cheap cargo transport to orbit. That’s something that NASA has shown that they can’t do effectively, while private companies have shown good promise here.
FWIW, the Dragon capsule has already safely transported live mice to the ISS and back again. Transporting live mammals isn’t that hard. Implementing all the necessary abort modes and doing the qualification is tedious, but straightforward.
The US and USSR have done all the manned “stunts” already, so there’s no need for private companies to repeat those. SpaceX is doing Dragon 2 because it’s a good-paying gig and because it helps their long-term goals, but it’s not like there’s some magical threshold when it comes to manned spaceflight.
Thanks; that sounds right to me. I think the STS is a good analogy. It is a pretty weird system, but is at least explainable when one understands the political factors that drove its development. I think you’re right that the PSLV is in the same boat, though I still wonder about the actual details here.
Well, that’s a nice story, but in practice even supposedly brilliant people often need someone to serve to check their wildly impractical schemes. In the case of sending vehicles to and ultimately “colonizing” Mars, I think the former is technologically possible but will not either deliver any significant return nor be as easy as Musk’s casual banter makes it appear to the casual viewer, and the latter is grossly impractical with the present technology of chemical combustion powered rocket engines and space habitation systems, notwithstanding the wide variety of issues with trying to extract resources, physiological responses to living in the much reduced gravity field of Mars, and the ever-present abrasive dust that has posed a problem to all of the rover vehicles.
Nor does the focus on Mars necessarily develop the necessary infrastructure to extract resources from space objects that is necessary to maintain a sustained human presence in Earth or solar orbit, or to send more elaborate missions (crewed or otherwise) to explore the outer planets and eventually other stars (at least by long range observation and parallax if not actually interstellar probes). SpaceX is, by inclination, focused on the propulsion aspect of getting to space and going to Mars, but there are many other issues that are equally challenging and will require revolutinoary developments in technology to overcome in order for interplanetary travel to become routine.
That being said, I hope SpaceX does make a 2018 attempt, and I hope they are successful if even not landing then in returning flight data from the attempt. I have to say that among all organizations I have seen, SpaceX is by far the best about capturing and returning as much high quality flight data as is physically possible, which is crucial to understand the actual flight environment and discover issues in the hardware. And they are not adverse to testing with known risks in order to gain knowledge, which is an increasingly and despiringly rare attitude in the current risk-adverse aerospace world.
Yeah, not only do I not have any more detail on the PSLV than you can find on Astronautix.com and Gunther’s Space Page, I don’t even know anyone who has worked with ISRO on a mission. Pretty much everything they launch is indigenously developed, and aside from some minor technology transfer from Russia in the 'Nineties, they’ve developed the rocket launch capability independently. For some time ISRO was widely thought to be a not very serious program, especially on early failures of their smaller launchers and the teething issues they’ve had with GSLV, but in comparison to the difficulties that both the United States and Soviet Union had in developing their rocket launch systems despite heritage from ICBM/IRBM programs with essentially a blank check, their history doesn’t look that bad, and they’ve actually deployed satellites and spacecraft doing real science and providing useful communications and remote imaging capability.
On the topic of odd mixing of propulsion systems, I have a toy model I’ve been playing with off and on for the past decade or so. While not intended to represent an actual rocket launch system I would propose, nor validated by any kind of subscale testing or independent validation, it serves as a useful exercise for comparative performance of various systems. One of the most successful configurations was a liquid hydrocarbon base stage with solid propellant boost augmentation, a cryogenic liquid upper/orbital boost stage, and then hybrid solid payload deployment modules to allow delivery of multiple payloads to various orbits. It’s an odd-looking duck that from a end-to-end performance standpoint doesn’t seem all that impressive, but the cost model that I’m using, which is a hybrid of that used in developing the current medium/heavy lift vehicles and my own experience, shows payload to LEO performance on the order of $500/kg, with bulk payloads making optimal use of the lift capability and payload envelop getting down around $200/kg. Again, this isn’t a specification for an actual operational vehicle (for one, it requires some technologies like base plug aerospike, and projecte aeroshock induction which are concepts that haven’t been proven out in full scale vehicles) but I believe it shows that there is a lot of trade space with different propulsion systems and configurations that get away from the high L/D cylindrical shape of most rocket launch vehicles. So, I’mnot inclined to be too critical of the PSLV if India has managed to make it reliable and suitably cost-effective. (I can only assume the latter; I have only the vaguest guess of what the vehicle costs to build and operate.)
Stranger
It goes to their public image and the ridiculously overstated promises that the private industry keeps making, along with the quasi-religious opposition toward doubters. The industry itself have made public relations an issue, trying to revive space fever. That requires people in space. Period.
I don’t disagree that robotic missions are the future of space. The space-happy are the ones who’ve confused the issue, trying to have it both ways. Want to do an unnecessary mission to Mars? Put some people in orbit and it will grease the path. It’s counterintuitive but that’s the way the public works.
SpaceX doesn’t need to grease any paths to send a robotic mission to Mars. They’re a private company and can just up and do it.
In the meantime, they’ve excited quite a lot of people with their powered landings and other successes. Their manned program will be frankly pretty boring in comparison; they’re just taking over a taxi service from the Russians.
In case anyone’s curious about the advantages and limitations of private space development, as opposed to arguing against a strawman, I’d recommend this series of videos by Dan Rasky of NASA.
He’s a NASA Senior Scientist that’s worked with SpaceX virtually from the beginning, as well as worked on the COTS (officially “Commercial Orbital Transportation Systems”, but in reality “Commercial Off the Shelf”) program. He’s also worked with Orbital ATK and has some insight into Blue Origin and ULA.
The talks are just a few minutes each and at a pretty high level, but he goes into many of the reasons why SpaceX was able to build the F9 1.0 for an order of magnitude less than their NAFCOM model suggested (~$400M vs. ~$4B). Plus, NAFCOM is considered a bit of a lowball estimate.
He also muses a bit on which development methodologies might be carried back to NASA and which cannot. Overall I’d say it’s a pretty level-headed and fair set of talks.
When Musk or someone else talks about “Silicon Valley engineering” or the like, it’s easy to be dismissive because it’s just vague marketing gobbledygook. Nevertheless, there are real differences between the “traditional” approach, which has origins in the military (and WW2 specifically) vs. the way software companies are run. These methodologies are not magic and do not work for everything, but they are real, and for some projects do enable order-of-magnitude cost reductions.
For my money, most of the key observations revolve around retaining design flexibility. The traditional approach is (in software, at least) called waterfall development, where you start with a very detailed and formal requirements document, and those directives flow “downward” into the implementation. This model works well for extremely large organizations, ones with a lot of geographical distribution, ones where expertise has become “siloed”, and so on. The military is obviously an example of this. But it is not a very efficient model, and if you can avoid all the things that cause rigidity, then you can allow compromise between teams. It may not be obvious how important this is but it’s really fundamental.
Rasky mentions a case at SpaceX where a bulkhead didn’t have enough structural margin, and there wasn’t room for reinforcement. However, the TPS (thermal protection system) did have extra margin that the bulkhead could use, and one team asked the other if they could use some of that margin. The TPS team said no problem, and so there was no need for redesign. Rasky said that kind of thing never would have happened at NASA–implying that the bulkhead would have to be redesigned, with both a monetary and schedule cost.
Again, this approach doesn’t work for everything, and sometimes can fail catastrophically. But for it the most part it is very efficient, especially if your organization can absorb a degree of failure.
The question the media is not asking or popular science or popular mechanics is asking is not can we go to Mars but can we bring space cost down enough to make it realistically!! I just don’t see the government or private sector pulling it off any time soon. After two or three mars trips people in congress will say enough is enough it is too costly. People living on Mars for 5 years or more seems prohibitively expensive.
Having 20 people living on Mars for 5 years will probably cost Billions and Billions of money. Even the super rich people may not have that kind of money.
A $500,000 one way ticket to Mars no way.
We tried single-stage-to-orbit (SSTO) and space planes in the 90’a it was too costly and did not work out. Read up on the X-33 and X-programs. The problem was heat tolerance in the aerospike engines. Composite and ceramic materials weren’t far enough along to stand up to the higher than standard temperatures.
In order for SSTO or space plane to become a reality.There will have to be a number things
- Better engines being ( more fuel efficient and or more powerful engine than what we have today.
- New better material.
With out that than there is no way SSTO or space plane will become a reality.
I was speaking of an SSTO from the Martian surface. Earth has an orbital velocity of 7.8 km/s and strong enough gravity that gravity drag is usually over 1 km/s. Along with aerodynamic drag, this means you need a delta-V of >9 km/s. Further, atmospheric pressure at the surface makes typical rockets inefficient (hence the aerospike and other advanced designs). This is very hard to reach with a single stage.
On the other hand, orbital velocity for Mars is 3.8 km/s, and gravity drag likely to be <500 m/s. The low pressure makes engines efficient even on the surface.
A Martian SSTO achieving 4.5 km/s, running on methane/LOX with a modest 340 s specific impulse, only needs a 0.74 propellant fraction–almost trivial by rocketry standards. The same vehicle on Earth (and ignoring sea-level effects) would need a 0.94 propellant fraction to reach the requisite 9.2 km/s. Virtually impossible and in any case leaving little payload.
Even with hydrogen fuel and a 450 s Isp, you need a 0.88 propellant fraction. Quite difficult when you consider the low density of hydrogen (and requisite large tanks) and low thrust-to-weight of hydrogen engines.
A Martian SSTO is actually easy enough that it may be possible to pack a small one into the Dragon 2 capsule itself (for a sample return mission). It would have a second stage, but used to get back to Earth–the first stage would get it to Martian orbit.