Tullius

The German news site Spiegel.com just posted an article (http://www.spiegel.de/wissenschaft/weltall/exomars-softwarepanne-liess-schiaparelli-abstuerzen-a-1118370.html): Schiaparelli crashed due to a software problem: An error in the communication between the landing radar and the navigationnal computer caused the computer to think that it has already landed, while it was still 2-4 km up. They are still investigating what the exact cause of the error was.

I think the gravity is not much of an issue, since we already know that humans can survive in 0g for over a year without too much problems. So an expedition to Mars should not be problematic in terms of gravity, no matter how the reaction of the human body to 0.38g is. For longer stays, it would certainly be interesting, if 0.38g doesn't cause the same negative impact as 0g, but for a short stay, it is a non-issue. The real problem is the radiation: Only 27 humans have ever left Earths magnetic field that protects us from the radiation in interplanetary space, and those only left it for a couple of days. And that is what SpaceX needs to prove, besides that their ship technically works. They need to prove that humans can survive this radiation with acceptable negative impact, even if there is a giant solar storm. And so we need to test the spacecrafts radiation shielding and the resilience of the human body to the remaining radiation levels, without exposing people to unacceptable risks. We know that SpaceX plans an unmanned test flight before sending the first humans, i.e. a test of the technical part of the mission. But there is no statement about how they want to make sure that the crew is safe. Maybe they will add an additional crewed flight in high Earth or lunar orbit to check if the crew survives the radiation levels, or maybe they just add such a ridiculous amount of shielding that the radiation inside the crew compartment is no more than the radiation on ISS, removing the need for a separate test.

Just because you find real life Jebediahs that still want to go on a mission to Mars despite you telling them that half of them won't survive, doesn't mean the risk is acceptable. Explaining to the public that the first human to put a foot on Mars is dead and that the guy waving so nicely on the photo close to the flag can't participate in the parade, because he is currently in hospital, would be very hard. However, I want to stress out that to prove that the ITS or any other spacecraft is safe for an expedition to Mars is rather simple: Just put it with a crew for 1.5 years into lunar orbit or very high Earth orbit, if everything works fine, you can send the next one to Mars, if not, you can return the crew within a few days.

ITS is just SpaceX's idea how you could transport humans to Mars, without the huge costs that NASA's idea based on SLS would imply, i.e. so that a company like SpaceX may be able to pay for it. There are huge difficulties (ISRU, radiation,...) and SpaceX knows them probably better than we do, but, if they want to fulfill Musk's goal of sending people to Mars, a system like ITS is the only possibility since they as company only have so much money. If they don't succeed in surmounting these problems, they won't be able to fly to Mars with ITS or anything else. NASA has already paid 8 billion dollars for SLS and is expected to spend the same amount during the next few years. They probably won't be able to go to Mars unless they get at least 100 billion dollars to develop and build the necessary space craft, i.e. it would be just as, if not more, expensive as the Apollo program. If NASA gets the funding, they can probably do it with their technology, but it is a very big IF as in they need another space race to get the money. You'll need an awful lot of Dragon launches to ISS (133 million $ each) to earn enough money to fund a NASA style mission from the profits. So SpaceX needs a cheaper option and ITS is exactly that cheaper option. Will it work? We don't know and Musk probably not much more, but SpaceX thinks that ITS is their best option to get people to Mars in the next 10-15 years at a cost of not more than a few billion dollars.

Considering the post: It looks like Schiaparelli (EDM) had some trouble knowing where it actually was inside the atmosphere. Still, the amount of data ESA has already gathered about the failed landing is impressive. An considering they already asked NASA for pictures, I guess it won't take a long before we get some pictures of the remains.

According to nzz.ch (a rather reliable swiss news site), people at the ESA control center were cheering at 18:40 CEST (about 1.5 hours ago). So they look pretty confident that the signal from Mars Express was the proof of successful landing. The only thing that probably is still missing: In what shape is Schiaparelli? Probably good enough to send data, but how much better?

Not looking very good, but not too bad either: Now, they are waiting for Mars Reconnaissance Orbiter to try its luck with catching a signal from Schiaparelli. Unfortunately, that will take an hour or two. Edit: Newbie handicap preventing me from posting directly.

"Relativistic Mass" is only a concept within the theory of special relativity, it is only a theoretical concept (to simplify formulas) and has no real consequences. In particular, it is not the classical mass that creates gravity. That is also why about half of the physicists don't use this notion, since, despite its capability of simplifying formulas, it confuses people. Also special relativity doesn't include a theory of gravity, it only describes the relative movement of non-accelerated objects (as in no force is applied to them). Its relativistic mass would be close to infinity, but its classical mass not. However, telling how gravity behaves in the context of special relativity is impossible, since gravity is a form of acceleration and special relativity doesn't tell us anything about accelerating objects. Acceleration is what general relativity is all about, but unfortunately I don't have a single clue about it.

That is the problem with the term "relativistic mass", the particle doesn't gain any mass, just energy. In special relativity, the energy of an object is expressed as E = gamma*m*c^2 , where gamma depends on the speed (and increases to infinity, if the speed of the object approaches the speed of light), m is the mass of the object (in the classical sense) and c the speed of light. Any particle that orbits a black hole orbits at a ridiculously high speed, which means that it has a ridiculously high energy. The "relativistic mass" is defined as M = gamma*m. The advantage of this notion is that the famous E = M*c^2 holds also for moving particles and in general it simplifies the formulas. However, M is some kind of mass that depends on the speed of the particle in the reference frame of the observer, i.e. it is a mass that is not constant and, even worse, it depends on the position you are observing it from. That is why some physicists accept the notion of "relativistic mass", while others reject it.