One of the major limting factors in space exploration, especially robotic exploration, is power. Sprit and Opportunity are carrying out their amazing exploration of Mars running on the power used by just a bit more than a 100-watt bulb. Hopefully, that's about to change. Aviation Week is reporting that NASA is gearing up to propose a series of missions that will use nuclear power. They're starting off relatively simple, using Sterling cycle power sources, which the article says are 4X as powerful as a standard Radioisotope Thermoelectric Generator (RTG), building over time to nuclear reactors in space. That sort of power will be critical if we're going to put people on Mars, or even on the moon for long periods. In the case of the moon, long periods means "more than two Earth weeks," because the lunar night is punishingly cold, and I've not seen one realistic design for a lunar base that can use solar power and batteries.

Missed seeing the launch live on TV by a couple minutes, but I'm really glad that Dawn got underway. Keep an eye on the web page, beause now that the craft has launched, they should be able to announce what other asteroids they'll be able to visit en route to Ceres and Vesta.

I've had a chance to think about the Google Lunar X-Prize a bit. I won't take the tack that others have, saying it's impossible, but I will list a few things that anyone thinking of going for the prize will have to keep in mind.

• Mass. This will be the biggest thing to keep in mind, like it is in most space missions. The $20M prize limits users to Falcon 1 (or Falcon 1e) class boosters if there's any interest in covering the cost with the prize. I think the idea of people wanting to recoup their investment has been overblown, though. Russia may have something more capable for the money. A Falcon 1e can lift about 700kg to low Earth orbit. The most it could lift to the lunar vicinity is 300kg, with another hit being taken for landing. Further calculations are required to validate even that number.
• Launch vehicle interface. This is related to weight, in that a very small rover will still have to connect to the relatively large payload interface for the booster. This can be worked through creative craft design or an additional adapter, though the second option includes a mass penalty (see first bullet)
• Guidance. The spacecraft can only count on GPS for the first few hours of flight assuming a direct injection to the lunar vicinity. This is enough time to get a solution on the injection orbit, but will be useless for further adjustments and landing without a quick adjustment in the first hours after injection while still below or just above the GPS constellation.
• Reaction wheels. They will be useful for attitude control, minimizing thruster firing in transit. Of course, they'll be useless once the craft lands on the moon, unless...
• High definition cameras. These are going to provide an interesting challenge. I've done no research on how much they weigh or how much power they use. The cameras can potentially serve double duty as star trackers, since they'll need to be radiation-hardened anyway.
  
• Travel speed. Many people may have heard of the 500 meter travel requirement and be thinking 'no big deal' due to the amazing travel distances covered by the Mars exploration rovers. When their travel time is divided by the time they spent on the surface, their rate of travel is quite low. A rover on the moon is limited to a maximum of 14 Earth-days of sunlight before the lunar night kicks in. Granted, the sunlight is full time for those 14 days, but you only get the full 14 days if you land at sunrise and immediately start roving.
• Lunar orbit. In my first estimation, it's unnecessary. Entering orbit would allow time to form an orbital position solution, but the landing approach would mess it up anyway. A flight right up to the equigravisphere (Earth/Moon balance point) then falling down towards the surface may limit landing site options (more work required), but should minimize propellant load.
• Precision landing. One of the bonuses includes landing at a previously-visited (i.e., Apollo) landing site. Very cool concept, though it will be difficult in practice. Such a small craft will be very susceptible to thrust variances impacting its landing location. Precision landing will require a mix of active ground control, on-board inertial guidance, and terrain tracking.

All that said, this challenge is difficult but achievable (like anything worthwhile), and I wish anyone giving it a try luck. Watch this space, as I may actually have something to offer teams entering. If you have any questions or comments on these ideas, shoot me an email.

Rand Simberg has an article on orbital fuel depots at Popular Mechanics. I just glanced through it, and it covers many of the same themes that make depots a good idea, though I have one issue with his discussion of letting anyone deliver to the depot. Chosing the orbital inclination of the depot can allow anyone to reach it easily (though making it more difficult to reach than necessary for others), and that must be factored in. Another quick nit deals with the artist's concept (assuming it's correct):stages mounted along different axes will complicate propellant flow. Guess I should look at the comments...good reading on the plane.

My latest article in The Space Review can be found here. I find it funny to hear from old friends that catch one of my articles and contact me with projects they've had in mind for some time. It's one of the reasons why I write.

I got a news release a couple days ago from JPL, announcing the discovery of cave skylights on Mars. I was hoping that the release was going to announce pictures of the skylights taken by the Mars Reconnaissance Orbiter, but it appears to simply be the announcement of the skylights themselves.

The thing is, this is old news. These cave skylights were announced at the Lunar and Planetary Conference in March. It appears as though JPL is doing the news release to coincide with a journal publication. Did someone miss the original announcement or is there some subtlety in the requirements for releasing news?

Something landed in Peru last weekend. According to news stories, the event made people sick and rained rocks on the area for several minutes after a fireball was visible. First reports where that it was a meteor, though later discussion talked about the possibility of it being a badly aimed SCUD missile, with unburned propellants producing the mystery ailments. The latest info in comes from scientists on the scene, and they say that it is indeed a meteor.

I'm thinking that the final word isn't in yet. I hope people are still following the story when it comes in.

Update a few minutes later: National Geographic weighs in saying that it was a rare stony meteorite. I do find it interesting that most articles go out of their way to say that no radiation was found at the site. The Nat Geo article sets the record straight:

"Everything has radioactivity, even underground rocks," Montoya said. "But nothing out of the ordinary was found."

I'm most of the way through watching the PBS special Seeing in the Dark. Quite cool. It's based on this book, and the author was heavily involved in the show's making (including starring and narrarating it). The focus of the show is how technology allows hobbyists to do serious work in astronomy. The work is appreciated because the professionals don't have enough telescopes to monitor all that needs to be monitored. One place mentioned in the show that I hadn't heard of was New Mexico Skies, a place where you can rent telescopes for a period of time over the internet or go there to carry out your own observations on-site. I'm guessing their services are more specialized than the more commercial (though still very cool) SLOOH.

The subtitle of the book speaks of "Guarding the Earth from Interplanetary Peril", I assume that deals with discovering asteroids, but it hasn't been mentioned yet in the show.

Winners of the Nobel Prize are usually a pretty classy lot. Many of them don't really seek the spotlight. That fact combined with the fact that a controversy always makes for better news than "business as usual" brought about a definite story when Nobel laureate Steven Weinberg spoke out against the International Space Station (ISS) and crewed spaceflight in general. I particularly like the use of the street term "disses" in the article title.

So, let's see. Here we have a top particle physicist who doesn't think we're going to get much science out of the ISS, but thinks that uncrewed missions are doing great. My guess is that one way this man gauges the usefulness of an item is by counting scientific papers. That is a valid metric for the scientific usefulness of something. If our only goal for the ISS was to produce scientific papers, then his moniker of "orbital turkey" would fit. One other thing to note is that Dr. Weinberg connects continuation of the ISS with cancellation of the Superconducting Super Collider, though the Wikipedia article cites a number of other possible reasons for the cancellation. It's possible that such a cancellation would make a particle physicist a little...bitter.

But long-term, our goals are (or if they're not, they need to become) much broader than a large number of scientific papers. We need to set those goals and then choose the right mix of robotic and crewed missions to meet the goal. Here are some goals that, I think, are very useful, and that remain the realm of crewed missions. I also grant the fact that the role of the ISS in their achievement is questionable, other than building our experience base:

• In-depth scientific study - you want to know about Mars metamorphic rock? Steve Squyers, leader of the Mars Exploration Rover project himself, said that a crewed mission with a rover and equipment at either location where are rovers are today would have achieved the same amount of science in days as opposed to the years it took Spirit and Opportunity.
• Resource exploitation - mining asteroids or any other celestial body will take old-fashioned gruntwork.
• Colonization - personally, I'd much rather see humans migrate off this planet than our robot posterity, though if robots were to colonize, I'm sure it would be worth several scientific papers!

NASA has put out the call for the next round of astronauts. They'll be the class of 09.

There are those who bemoan the fact that you have to apply through the US Government's civil service application process USAJobs.gov. They claim that this makes being an astronaut "just a job." I have news for them. It is just a job. It's a job that's different than many others, combining physical danger, tedious memorization of procedures, long waits for a chance to 'prove yourself' in a mission, elements of being a "rock star" or other famous person, and an awesome view for a few days when you actually get to do what you've been trained to do, but it is just a job.

That won't stop me from applying.

My initial excitement has passed over the Google Lunar X-Prize, announced yesterday as a $20M prize for landing on the moon and roving 500m. There's a $5M second prize and $5M in bonuses for doing cool stuff like photographing Apollo hardware already sitting on the surface. There's a news story on it here, and plenty of discussion about it here and here, and the reception is best described as tepid in my opinion.

There are some complaints that the dollar amount is too low. It is less than I expected, give the pre-release hype that it was going to be the largest prize offered (it isn't, America's Space Prize is), but I think there's enough there that someone will be willing to try for it, and someone will be willing to get their name up in lights along with Paul Allen as the investor who helped make it happen.

Some of the partnerships mentioned in the announcement are intriguing. Elon Musk is offering cheap rides on his Falcon rockets (I'm assuming Falcon I, since the others cost more than the prize is worth) and free command and control through the Allen Telescope.

This is very cool stuff, and I hope several teams take it on. Just the fact that the first X-Prize succeeded increases the chances that this one will as well. For example, the first X-Prize was announced before it was funded, and this one is funded from the start. I've written about prize fatigue in the past, but with Centennial Challenges mired in Congressional language and perhaps agency neglect, I think fatigue is less of an issue.

The recent post on Iapetus reminded me of the role Jupiter's moon Io played in our understanding of the speed of light. There's more to the story, according to this book, including a challenge laid down by a grad-student equivalent challenging his mentor in public.

Looks like Cassini entered safehold after its close encounter with Iapetus. Apparently, all the data was captured and will eventually be beamed down, but it took some extra commanding to do so. Details, including Iapetus' role in the book version of 2001: A Space Odyssey described here.

Old news, I know, but I didn't think of anything original to comment on until I saw this picture at NASA Spaceflight. Looks like a Kistler K-1 (or whatever the latest designation is) second stage on its side in a hangar, ready to go, if only we had a couple more million dollars. Just one problem...it looks computer generated to me. This all goes to the question of how complete their system ever has been. If hardware of that size existed, it would be a simple matter to post pictures of it on the web, as others have done. The RpK website has one picture in their gallery of actual hardware, and it was an engine test firing. They bought their engines from Russia, pre-built.

Remember, I'm one of the ones who really wants to see someone succeed at this business. I just haven't seen anything to show me that these guys would have been the ones to succeed given any amount of money.

I'd really like to know what was actually built for the hundreds of millions of dollars the company's been through.

The Dawn spacecraft is back at the launch pad. After a delayed set of launch attempts a few months ago (interrupted by the launch of the Phoenix mission to Mars), the spacecraft was taken back to a hangar for storage. Now a new launch date is set for September 26. This is one cool mission, using ion propulsion to visit two of the largest asteroids, each of which has a radically different makeup. Also, the craft will likely be able to fly by a bunch of other asteroids, but they don't want to start predicting which ones or how many until the launch, because the list is highly dependent on launch dates.

That's how I describe my enthusiasm for Photonic Laser Propulsion from the Bae Institute. I just received a press release making some pretty big claims through an email list that I'm on. If I read it correctly, the propulsion system aplifies laser light 3000 times to generate thrust and uses no propellant. 3000 times a very very very small number (the thrust generated by a laser) is still a very very small number. Scalability will be the key.

In curiousity, I wore my GPS Receiver (a Garmin Forerunner 205) while I followed my daughter around a kids activity center a few weeks ago. The resulting plot is shown on the right. We covered about a mile and half of distance overall in 45 minutes, but of course most of it was running. GPS, a program I worked on, is the reason this post counts as a space post.

Looks like it won't hit us here in the DC area, but tropical storm Gabrielle (this plot will be altered as upadates come in. When I made this post, all but one of the models had Gabby nicking the coast and heading northeast. The dissenting model has here shooting west-northwest into the United States) is definitely giving North Carolina a brush. Just a reminder that if you ever want to see what the Eastern Seaboard of the US looks like from space, go to this page, which has a colorized version of the latest GOES satellite image.

There's no shortage of predictions about what the next 50 years of space activity will bring. The names of the people offering these opinions may inspire you to pay a bit more attention.

The X-Prize Foundation is creating buzz about a new prize they will announce on Sept 13th. They're claiming it to be the "largest international prize in history," which means it would have to beat out America's Space Prize, which is set at $50M. Ought to be exciting.

My son was asking me what the space station looked like after I showed him this movie of it flying past the moon. In looking for an image, I came across this one, taken by the Endeavour crew as they left. Note the orbiter's shadow cast on the station itself.

Amidst the celebration for other spacecraft, another mission celebrated a milestone which probably won't get as much press, but has some close-to-home impacts. Landsat 5 passed 125,000 orbits on Saturday morning ET. It was actually about 0445 ET, but I wasn't going to get up for it. 125,000 trips around the Earth is equivalent to:

• 5,558,262,802 km (3,446,122,937 mi) Note: Neptune is 4,553,946,490 km from the sun at aphelion
• 14,459 trips to the moon (1-way)
• 60,458,297 trips around the beltway
• 31,000,000 scenes flown over (not all of the scenes were land scence, and not all the land scenes were imaged) Scenes are described here.

The past doesn't matter, however, because Landsat 5 and/or its sister craft, Landsat 7 need to keep operating for about 25,000 more orbits when their replacement, the Landsat Data Continuity Mission is flying.

There's not a whole lot of space news going on out there. I see that CNN has a news article up in their front-page science section (where they usually put their space stuff) from August 20th.

There is an article about satellite imagery of Noah's Ark, which reminded me of my own brush with biblical archaeology. While I was in Turkey, a man came and spoke at the chapel. The topic was the search for Noah's Ark, and I was bored so I went. His talk dealt with his privately-financed expeditions to the region, and how if he could prove the location of the ark, then lots of people would want to travel there, generating tourism trade for Turkey and everyone would win. While remaining skeptical of his methods and overall goal, his talk was entertaining until the last couple lines, where he said it was important to prove that Noah's Ark was true, so that the word of Christianity could spread through the internet and bring the end of the world, when the UFOs would arrive. The last part of his talk is why I don't have a link to the site, but his name is Charles Willis. If you'd like to search for yourself, go ahead.

As part of the 30th anniversary of the first Star Wars movie, the next shuttle mission will take Luke Skywalker's lightsaber into space with it.

While I'm not as cynical as the (aptly named) space cynics about this, it does strike me as a bit lame.

No word whether astronauts will try to re-enact a battle, though the lack of gravity (and lack of really big pits to fall into, which seem to be a standard feature of lightsaber battles) would make things look quite different.

The Mars Rovers are slowly revving up for some activity. Here's a quick summary of some of their recent news:

• Spirit becomes the second-longest running craft to operate on Mars. It beat out a 70's superstar
• Talk about the rovers not liking the cold as they age, including early indications that Opportunity's front right wheel might go the way of Spirit's and stop working soon.
• Discussion about what would happen if battery levels got too low (the article is from a month ago, so it looks like things have gotten better)
• Brightening skies, always good news for a solar-powered craft. If only we'd get a cleaning event that takes dust off the arrays.

In other news, the Mars Reconaissance Orbiter confirmed the existence of a veritcal shaft in a lava flow. Very cool stuff for potential living spaces on Mars.