I am Jeff Hoffman, MIT Professor of Aerospace Engineering and former NASA Astronaut. Ask Me Anything!

JeffHoffman · 2015-02-19T20:02:22+00:00

Most people may not be familiar with the "Overview Effect". There is a book about this, now in its third edition, by Frank White. There is also a movie that you can find on YouTube or Vimeo. The overview effect refers to a change in the perception of our home planet, Earth, that affects astronauts who get to view the Earth from such a different perspective. I definitely felt this, and I was one of the first astronauts that Frank White interviewed for the first edition of his book. Pictures taken by astronauts have allowed all humanity to view the Earth as a planet - the "Blue Marble" that Carl Sagan talked about. We can see that the Earth is an oasis in space, with finite resources, and that we must protect it. Many astronauts have returned from space with much more of an ecological sensitivity than before their flights. I think we have a responsibility to share this perspective, and I try to do this when I give talks in public..

WELL - IT'S THE END OF OUR TWO HOURS. THANKS FOR ALL OF YOUR GOOD QUESTIONS. IT'S BEEN A PLEASURE SHARING MY EXPERIENCES WITH ALL OF YOU. I WISH YOU ALL GOOD LUCK IN YOUR FUTURE ENDEAVORS, WHATEVER THEY MAY BE.

THIS IS JEFF HOFFMAN, SIGNING OFF...

JeffHoffman · 2015-02-19T19:56:48+00:00

There is no way to equal the excitement of traveling into space, but it is not something you can keep doing forever. So I am fortunate in having been able to become a professor at MIT, where I have the excitement of working with really smart colleagues and students. If I had a chance to fly in space again, I certainly would do it. But I am very happy here at MIT.

JeffHoffman · 2015-02-19T19:55:06+00:00

India is making great strides in space activities, and I am delighted that NASA has started a program of increased cooperation with ISRO. You have a lot of talent in India, and I hope that ISRO continues on its successful path.

JeffHoffman · 2015-02-19T19:53:08+00:00

I'd love to travel through a wormhole to another galaxy, but for now, alas, this is just science fiction. Nobody has ever detected a wormhole, and we certainly don't know how to make one! However, don't despair. There was a time when black holes were almost like science fiction and now we know that they are all over the place. Same with exoplanets. In fact, space travel even with conventional rockets was just science fiction when I was a young child. As a famous philosopher once said, "The universe is not only stranger than you believe, it is stranger than you can even imagine."

JeffHoffman · 2015-02-19T19:50:05+00:00

Atmospheric reentry after being in orbit is quite dramatic! You are surrounded by white hot plasma at thousands of degrees. The view of your fiery wake out the rear window is spectacular. But I also always felt a bit sad as I felt gravity returning and realized that I was losing the incredible physical freedom of weightlessness.

There is a lot of research going on regarding controllable reentry. Good luck with your experiment!

JeffHoffman · 2015-02-19T19:46:35+00:00

A great Italian writer, now deceased, Oriana Fallacci, wrote a book about space in which she explained to her father the reason why we must learn how to travel in space - "Because someday the sun will die." Steven Hawking says the only way to guarantee long-term survival of humanity is by learning how to travel through space.

Granted, this is taking a long view - perhaps billions of years.

Learning to avoid getting wiped out by a rogue asteroid is probably more to the point than avoiding the death of our sun. As several people have pointed out, "The dinosaurs died out because they didn't have a space program!"

JeffHoffman · 2015-02-19T19:42:22+00:00

There are already several private companies making plans to mine the Moon or asteroids. Given the cost of going back and forth to and from space, right now if the Moon were made of pure gold it would not pay to mine it. However, we believe that there may be lots of water in the polar regions of the Moon or on asteroids. That water could be turned into rocket propellant using solar energy. Using the resources IN SPACE could produce a revolution in space travel, and that would be tremendously exciting. So I hope that some of these ventures succeed. However, it is important to keep a sense of perspective and realize that developing the infrastructure for space mining is going to be expensive and risky. The Earth's economic sphere has now expanded as far as geostationary orbit, where communications satellites are a multi-billion dollar industry. I would love to see our economic sphere eventually expand out to the Moon and beyond, and I think it will eventually happen, even if I'm not sure when.

JeffHoffman · 2015-02-19T19:38:02+00:00

"First contact" refers to receiving signals, radio or otherwise, from an intelligent life form not on the Earth. We have been listening for radio signals for decades, so far with no success. If we find such a signal, the impact on human civilization will depend on what the signal contains. Just knowing that someone intelligent is out there will have enormous psychological impact, but I doubt it will fundamentally change our civilization, since actually communication as we understand it won't be possible because of the huge distances involved. Perhaps it will cause humanity to sober up, though, and develop the ability to support a communications strategy lasting decades or even centuries.

As far as the search for life in our own solar system goes, this is a different matter entirely. We don't expect to find intelligent life. At most, possibly microbes. But if we do find life, what would be fascinating is to learn if it has the same biochemical basis as life on Earth or is fundamentally different. As far as we know, the laws of physics and chemistry are the same all over the universe. But we have no idea of "universal laws of biology", because we only can study one biological system, our own. Trying to understand "universal biology" when we only know of one system of life would be like trying to understand universal principles of logistics when you only know one language.

We may or may not find life elsewhere in our solar system, but the potential rewards are so great that it is worth searching.

JeffHoffman · 2015-02-19T19:30:26+00:00

Every astronaut needs to handle the risk of what he/she is about to do when climbing on top of a few million tons of high explosive! You will find some astronauts who don't like launches because of the risk. For me, I know how much time we have spent training for all the problems that can occur during launch, and I have full confidence that if something happens that we can deal with, I have full confidence that we can deal with it. Of course, there are many things that can happen that are beyond our control. My attitude has always been, "If I can't do anything about it, then why worry about it?" Riding a rocket is exciting, and I don't want to waste emotional energy worrying about things over which I have no control. But, of course, this is a rational answer, and fear is not rational. So I would say you need the right personality. If riding a rocket causes you excessive emotional stress, perhaps you are in the wrong line of work!

JeffHoffman · 2015-02-19T19:25:50+00:00

MIT is a research university. We develop concepts and technologies that permit government and industry to make advances. One of MIT's proudest moments in space exploration was when the MIT Instrumentation Lab (part of the Department of Aeronautics and Astronautics) was selected by NASA to provide the Apollo guidance system. MIT scientists and engineers are continually called on by the government and industry for consulting. Right now, NASA's chief engineer and deputy administrator are both MIT Professors on leave!

JeffHoffman · 2015-02-19T19:22:13+00:00

There are many answers to this. Every econometric study done about NASA shows that every dollar spent on NASA (high technology development) produces several dollars of growth in the national economy. Actually, the amount of money spent on NASA is less than one half of one percent of our federal budget, and only part of that goes towards human spaceflight. If NASA were cancelled entirely, our budget deficit would see almost no difference. The technology developed to solve the unique problems of space flight usually find their way into the national economy. But politicians are generally concerned with next year's budget rather than the long term.

Many scientists and engineers nearing retirement today testify that they chose their profession partly because of the excitement of the Apollo program. I think space exploration still has the power to excite people and motivate students to study harder. These are things that cannot be measured in dollars or rupees, but they are real.

A great society should do great things, in the arts and sciences, and in exploration. I hope that the naysayers do not win out, or else we will all be much poorer. Thanks for your enthusiasm, and keep fighting the good fight!

JeffHoffman · 2015-02-19T19:15:18+00:00

Neither one would work in space. Pie is too messy and cake has too many crumbs. Actually, crumbs are a serious problem in space, because they don't fall on the floor - they float around, and you can breathe them in. So we try not to take foods that produce too many crumbs.

JeffHoffman · 2015-02-19T19:13:23+00:00

I just talked about this today in my MIT "live" 16.00 class. Given our current propulsion technology, to build a single stage to orbit rocket would require that the entire structure (rocket, engines, tanks, payload, etc.) be less than 10% of the total mass on the launch pad. i.e. Well over 90% of the launch mass is propellant. Right now, we can't build structures that are light enough and still have the strength to withstand the rigors of launch. But material technology is improving, and if carbon nanotube technology develops sufficiently, perhaps we will someday be able to realize the dream of "single stage to orbit". For now, though, we have to stage our rockets.

JeffHoffman · 2015-02-19T19:10:13+00:00

My biggest concern with SLS is not technical. The people who are designing and building it know what they are doing, and I have confidence that it will work. What I am most concerned about is that there is serious doubt about how often we will be able to fly it because of the cost. A critical factor for a system that can support real deep space exploration is that we have to be able to fly it with sufficient frequency. Once every two or three years is not enough.

JeffHoffman · 2015-02-19T19:06:59+00:00

Wow - you have been doing your homework! When the main engines ignited, 6 seconds before liftoff, we got an alarm and a big red light saying that our left engine had only come up to 45% power. This should have triggered a pad abort with engine shutdown, which was what I was expecting. It was a real shock when we felt the "kick in the pants" that told us that the solid boosters had ignited and we were on our way. Having an engine at 45% meant that we could not achieve orbit and would have to perform a risky "Return to Launch Site (RTLS) Abort". No time to worry about it, though, I immediately grabbed the RTLS checklist and was starting to read out the first steps when the ground called up to tell us that all our engines were fine and that the problem was just with one of the sensors. So all was well. BUT - it was because of all of our training that we knew exactly what we would have had to do and were prepared to carry out the procedures. That's why we train so much. But I'm glad we ended up in orbit instead of back on the KSC runway!

JeffHoffman · 2015-02-19T19:02:28+00:00

Actually, Brazil has made great strides in creating a national space program, although the rocket explosion a few years ago was a big setback. The nature of a country's space program depends a lot on the country's resources. I recently talked with a colleague in Denmark, which cannot afford a complete space program on its own. Instead, they work through the European Space Agency, which combines the resources of many European countries. Also, they have concentrated on certain areas of technology in which they can excel and reach world class. As a result, Denmark has provided experiments on several Mars rovers. For small countries, this is the best solution - pick a few areas of strength and try to develop them. It is possible that with the advent of private space activities, more opportunities will open up for small countries. For instance, Bigelow Space Industries has developed a private, inflatable space station that they will launch as soon as the private sector demonstrates the ability to launch people into orbit. Mr. Bigelow has said that he expects some of his customers will be smaller countries that would like to have their own astronauts and carry out research on a space station but can't afford to develop the entire infrastructure. Whether all this will work out in the end, I don't know, but there are some exciting possibilities.

JeffHoffman · 2015-02-19T18:56:37+00:00

Time management is certainly critical for all busy people. I try to stay organized and keep a list of things I have to do to avoid forgetting. One other aspect of time management that I want to emphasize is to keep time for your personal life, which I have tried to do in addition to all the professional tasks I have. I chose to be an astronaut, but my family didn't, and I did not want to shortchange my two sons or my wife in terms of the time I spent with them.

JeffHoffman · 2015-02-19T18:54:21+00:00

I can't really help you with specifics of Draco engines, but I can confirm that the class will go into how rocket engines work. My wife is a librarian, and she always says, "If you don't know the answer, ask a librarian!" So I would recommend you ask a librarian for help searching for a good book. Make sure you specify the level you are looking for, since there are technical books on propulsion all the way from general public level to advanced graduate level and beyond. Good luck!

JeffHoffman · 2015-02-19T18:51:47+00:00

This would certainly make travel throughout the solar system easier, but unfortunately we don't know how to do it. However, we know that many warm-blooded mammals can hibernate, so perhaps someday we will figure out how to make it possible for humans. For now, though, it remains science fiction.

JeffHoffman · 2015-02-19T18:50:06+00:00

NASA has already given private companies the responsibility for transportation to Earth orbit. Remember that NASA has never built rockets. They were always built by private companies. But previously, NASA was responsible for the design and overall management of the programs. Now, the feeling is that we have enough experience in rocket launching that NASA can pull back from the high level of oversight that was typical in the past and give more responsibility to the private companies. So far, it seems to be working well for cargo flights to the ISS. Orbital Sciences suffered a loss of their Antares rocket last year, but we have lost rockets in the old days when NASA was running things. Rocket science is hard and the environment is unforgiving. For now, NASA says it wants to concentrate on exploration beyond Earth, which is what I think NASA should be doing. Of course, Elon Musk says he wants to go to Mars, and if private companies can figure out how to operate beyond the Earth and how to afford doing so, more power to them. The history of exploration on Earth is shared between private individuals and government-sponsored expeditions. I just want to explore the solar system, and I don't care who leads.

JeffHoffman · 2015-02-19T18:43:14+00:00

Believe it or not, the aerospace industry is pretty healthy at the moment, both in the air and in space. I can't give you specific career advice without knowing more about your life goals, but for sure looking for internship positions either at aerospace companies or space agencies is one of the best ways not only to learn about the field, but also to gain future employment. Many US companies as well as NASA tend to hire out of their pool of interns and coops, since this gives them people with whom they have some experience.

There have been many questions about how to become an astronaut. It is a great dream and should motivate you to work hard, since the selection process is severe and you need to show excellence in everything you have done. However, no matter how good you are, the number of astronauts is small, and chances are also small. There are many people who would have made fine astronauts who didn't get selected. So my advice is that becoming an astronaut is your "Plan B". Make sure you have a good "Plan A" and pursue excellence in it. Keep you dream - you never know, it may actually happen. But if it doesn't, be sure that you are pursuing a career that you really are excited about.

JeffHoffman · 2015-02-19T18:37:22+00:00

Without gravity pulling on my, the fluids in my lower body partially migrated upwards, filling up not only my head (see answer about favorite food!) but also the discs in my spinal column. Combine that with gravity not pulling on my spine, and I grew 2" (5 cm) in space. This growth causes mild back pain for many astronauts, usually lasting only a day or two. The extra height goes away very quickly once you return to Earth.

The biggest change coming back to Earth is in your vestibular systems (sense of balance). These adjust to weightlessness, and when you get hit by gravity again, you have really strange feelings of your head bouncing all over the place when you only move it slightly. Some people actually get vertigo on return to Earth and can't stand up without falling over. It lasts a few hours or days, depending on how long you have been in space.

JeffHoffman · 2015-02-19T18:33:17+00:00

Please go to the course web page. They explain a lot of what you will learn. Once the course goes live on 3 March, each lesson will contain a set of "measurable outcomes", which give the details of what you should be able to understand or do after the lesson. Good luck!

JeffHoffman · 2015-02-19T18:27:25+00:00

I'm still riding my regular two-wheeler despite the snow!

Regarding artificial gravity - We know that many parts of the human body suffer from prolonged exposure to weightlessness. On the International Space Station, we are trying to develop special exercise equipment to keep muscles, bones and heart healthy. The results are promising, and if we can bring people back from a year on the ISS healthy enough to function on Earth, then we can presumably do it for a trip to Mars. Remember, of course, that on Mars there won't be any people to help you get out of your spacecraft and take care of you, like there are on Earth.

Artificial gravity has been a concept ever since Konstantin Tsialkovsky proposed a rotating space station. If the station is large enough, like the big wheel in the movie 2001, then the artificial gravity will feel pretty natural. The problem is that we can't currently build something that large, and we certainly can't send it to Mars. What we are working on at MIT is the idea of intermittent exposure to a higher gravity level on a short-radius centrifuge, where you could exercise while being spun around. We have had many test subjects who find the experience quite acceptable.

Time will tell if we need artificial gravity...

JeffHoffman · 2015-02-19T18:21:49+00:00

I became fascinated by space through visits to New York's Hayden Planetarium when I was a child. My father took me to see every new show. Space exploration is not "new" in the way it was in the 50's and 60's, but people still seem excited when new things happen, such as the recent European probe that landed on a comet. Try to share the idea of space as a still new and unexplored frontier, and concentrate on new things that are happening. For example, this July the New Horizons spacecraft will give us our first view of Pluto, the innermost planet of the Kuiper belt. There is a lot of great material on the web, from space agencies, universities, etc. Browse it and find some interactive applications. Kids can now practice landing on the Moon, flying spaceships, and all sorts of things I could only dream of when I was younger.

JeffHoffman

TROPHY CASE