Visiting an Old Friend
Grunsfeld, in a white spacesuit, holds a tool

Grunsfeld performs work on the Hubble Space Telescope during the STS-109 mission in 2002. Image Credit: NASA

When the STS-125 mission of space shuttle Atlantis launches later this year, its goal will be to bring new life to an old friend.

The 11-day flight will be the last time a space shuttle will visit the Hubble Space Telescope. The crew will install two new instruments, repair two inactive ones and perform the component replacements that will keep the famed scientific instrument telescope functioning to at least 2014.

Among the crew will be astronaut John Grunsfeld, who will have flown on three of the five Hubble servicing missions since the telescope first was launched in April 1990. Two other crew members, Commander Scott Altman and fellow Mission Specialist Mike Massimino, will be taking their second trip to the telescope. Pilot Gregory C. Johnson and mission specialists Andrew Feustel, Michael Good and Megan McArthur will be making their first spaceflight.

During five spacewalks, the astronauts will replace the telescope's batteries, orientation-control gyroscopes and other hardware. The crew also will add two powerful new scientific instruments -- the Wide Field Camera 3 and the Cosmic Origins Spectrograph.

During an interview, Grunsfeld talked about why the STS-125 mission to service Hubble is important, and what it will be like to visit his old friend one last time.

To put the mission in a little bit of perspective, what, for you, is the most interesting, amazing or otherwise cool thing about Hubble or its results?

Wow. That's going to take a while. I think there are two things. It's kind of what's amazing about astronomy.

Grunsfeld in a white spacesuit, holding his helmet

Grunsfeld will be making his fifth spaceflight on the STS-125 mission. Image Credit: NASA

Hubble uniquely has been able to look in the atmosphere of a planet orbiting a nearby star and figure out what's in that atmosphere. When I grew up as a kid, we didn't know there were any other planets outside of our own solar system. It was widely speculated that planet formation was an incredibly rare event, and that it's possible that other planets just don't exist in our galaxy, and it's just this special situation where we happen to have planets around our sun. And, of course, that's the typical, human-centric "We're so special."

Because of Hubble and other telescopes, we've now discovered that there are probably planets around every star, or virtually every star. There are solar systems around most stars. And the fact that we're here on a planet, Earth, means that it's likely there's lots of other Earths out there. But we've only learned that in the last decade. And we know of almost 300 planets outside of our own solar system now, our neighbors.

Hubble has uniquely been able to actually look at one of those planets, and determine that there are sodium and methane and water vapor. So we're starting to look at other planets. And it's not very far-fetched to think that it will be soon that we're able to find an Earth-like planet and know what's in its atmosphere and be able to detect the signatures of life if they exist. So that's pretty amazing.

The other (interesting thing about Hubble) is that using Hubble and ground-based telescopes and other NASA satellites -- but Hubble was really the fleet leader -- we've determined that three-quarters of the universe is filled with a mysterious "dark energy." And we don't know what it is. The way we found this out is, we looked at the Hubble expansion -- the big bang and the expansion of the universe -- and found out that it's accelerating. We all thought as scientists that it would be slowing down, but it's actually accelerating. And there's no known cause for it. Astronomers, being really clever, if you can't see what the cause is, they call it "dark." And if it's a pressure -- which in this case it is, it's a cosmic pressure -- it's an "energy." It's a "dark energy."

So if you tally up what's in the universe, three-quarters, or 71 percent, of the universe is dark energy. About a quarter of the universe is "dark matter." We know it interacts with gravity, but we don't see it. So, of course, it's "dark." And because it has mass, or interacts with other things that have mass through gravity, we call it "matter." That only leaves 4 percent for the rest of us. So everything we see in the universe -- all the stars, galaxies, gas, us, the Earth, our food -- only accounts for 4 percent of what's in the known universe. It's a tiny fraction.

So there's a lot to learn. It's a good opportunity. If you want to be a scientist, there's a lot you can figure out.

As a scientist, is there any particular research or discoveries that you hope this servicing mission will enable?

Hubble above Earth

The STS-109 crew took this picture of the Hubble Space Telescope after completing the last servicing mission. Image Credit: NASA

There are lots of incredible things this mission is going to do. I think this mission will enable (three things): more research into what is the mysterious dark energy and dark matter; looking at more planets around nearby stars to maybe find the signatures of life; and the last one, each time we visit the telescope and put new scientific instruments -- in this case the Wide Field Camera 3 and the Cosmic Origin Spectrograph -- we reinvent the telescope by making it 10 or 100 times better. Whenever you do that, there are always discoveries that you couldn't have anticipated that are enabled, and that's been true every single time we've done a servicing mission.

We put in the STIS instrument, Space Telescope Imaging Spectrograph, and suddenly we proved that black holes exist; we proved that the center of every galaxy has a massive black hole. We also discovered that we could see the atmosphere of a planet around a nearby star -- that kind of stuff -- with STIS.

With ACS, the Advanced Camera for Surveys, which Mike Massimino and I installed on the last mission, we put that in, and suddenly we were able to see these distant supernovae that showed that the universe is accelerating, and dark energy was discovered.

So we're putting two new instruments that can see even further back in the past, closer to the big bang, and also that can do the physics of the universe in unprecedented detail, that being Wide Field Camera and COS. Who knows what we'll discover.

You touched on that you've been there before. Since this is planned now as probably the final servicing mission, are you excited about going back, and is there any sense of bidding farewell to an old friend?

When I first went to Hubble, as an astronomer and as a scientist, it was a dream come true. And as an astronaut, the Hubble missions are premiere missions because Hubble is so important to science, so important to humanity, that it's just a very special event. But as an astronomer, it was sort of the holy grail of missions.

A montage of Hubble images

These images of (clockwise from top left) the Helix Nebula, Mars, the Eagle Nebula and the black hole at a galactic center are just a few of the incredible vistas captured by Hubble. Image Credit: NASA

I got up there, and it was just phenomenal. I couldn't believe my incredible good fortune, so to speak, or privilege, that I was able to be up close and hug the Hubble Space Telescope. And after just a short number of days being up on the telescope, when we deployed the telescope, I kind of felt like I'd met this new friend, and just after spending a few days had to leave, and that I would likely never see the telescope again.

Fortunately, I guess I did a good job; they let me go back. When we got back to orbit, it was like seeing an old friend. I was just so thrilled to be there and spend a few days with Hubble, and bring it up to date, and renovate it so it could go off and do new science. As it floated off in the distance, I was convinced I would never see it again. And here we are going back.

So I suspect I'll feel like I'm visiting a very dear and close friend. When we'll deploy it, I can't really anticipate how I'll feel. But I think actually I'll be pretty happy because of the fact that, at one point in 2004, we were told we couldn't go back to Hubble. The thought then was, Hubble's not going to last very long.

By the end of the mission, we will have given Hubble something like 5 to 10 more years of useful scientific lifetime. And I'll just feel that that'll be an incredible thing that we will have accomplished as the big NASA team to pull the mission off. It's a very complex mission and a very difficult mission. And when we pull it off as a NASA family, I think it's something NASA's going to be very proud of, and will enable incredible science.

So instead of being sad, I think I'm going to feel like, "Wow, this was quite the experience." Because, in the end, Hubble's not a living being: it's a satellite. Even though I'm sure I'll feel -- it's not even remorse, I can't find the right word for it -- a little bit of sadness that we're deploying Hubble, because I have already gone through that sadness that we would never see Hubble again, and then having that turned around, I think I've already got that emotion past me. I think I'll just be thrilled that we were able to go up and fix Hubble.

Since you've talked about the discussion in 2004, this obviously is the last non-station mission, with all the safe-harbor issues that involves, why is this mission worth the risk?

The crew of STS-125 with a model of the Hubble Space Telescope

The astronauts selected for the final shuttle mission to perform work on the Hubble Space Telescope are (from left) Megan McArthur, Michael Good, Gregory C. Johnson, Scott Altman, John Grunsfeld, Mike Massimino and Andrew Feustel. Image Credit: NASA

All of spaceflight is risky. The first thing you have to get over is, is spaceflight worth the risk of any kind? And I think the answer is yes. I think exploration, and humans pushing our limits, and specifically Americans pushing our limits and developing a challenge in space and new frontiers under the oceans, are an intellectual and a human imperative.

Then you have to ask, we don't want to take reckless risks to go explore. We're not doing this for bragging rights. We're doing it to improve life on Earth and to improve the future of humans. So what kinds of missions are worth doing that for? And Hubble is certainly in the category of a mission that's worth risking lives for, and that I feel personally is worth risking my life for. Hubble is perhaps the most significant scientific instrument ever created by humans. And science is the quest for knowledge, to find fundamental questions. Where did we come from? And by extension, where did the universe come from? How old is it? Where are we going?

For students who want to be a part of that, or want to get involved in NASA or space exploration, what advice do you have?

Well, my advice to students, regardless of what they want to do, whether it be space exploration or science or engineering, in general, my advice for life is, find something you love to do, and work hard to be really good at it. My motto is kind of "Work hard, play hard, have fun."

The STS-125 patch depicts the Hubble, the shuttle, stars and galaxies, and the names of the crew members

The black background of the STS-125 patch symbolizes dark energy and dark matter. Image Credit: NASA

I think if you find something you love doing, then you'll find that it's fun to do, almost by definition. So I encourage students to work really hard in math, because math is the language of science and engineering. Once you understand science and engineering, you can do anything, whether it's inventing new things, whether it's saving lives in biology and medicine, even in business, the very high-tech world that we live in.

And hopefully some students will say, it's great for humans to go and explore other planets, but we also ought to have a planet here that we can explore. I'm going to work on inventions to help save the planet.

You know, after all, planet Earth is a spaceship as well. Anybody who ever operates in or around spaceships knows that whatever you put in the spaceship is what you're going to be eating and breathing. And here we are on spaceship Earth, putting stuff in our atmosphere and our water that we may not want to eat and breathe. So we need to be smart about that, too.

As someone who was involved in shaping the new plans for space exploration, what would you like to share with today's students about where we're going?

When I was in school, I was inspired by our country trying great things. Those great things were going to the moon and building spaceships to take people there. We went to the moon, and we built the International Space Station, and we repaired Hubble. These are things we should all be proud of. Their generation is going to take it even further, beyond the Earth-moon system, to visit near-Earth asteroids, to go to Mars, to find out what's out there.

If there's any science fiction fans, Star Trek talks about, "to go where no human has gone before." I took some editorial license there; I think it said "to go where no man has gone before." The universe is an incredible place. It really is limitless, and the exploration program is a start of going out and beginning that exploration of the universe with people.

Hubble is a part of that.

Related Resources
John Grunsfeld   →
STS-125: Mission Information
STS-125: Servicing Mission 4 Essentials
Hubble Space Telescope
NASA Education Web site

David Hitt/NASA Educational Technology Services