It’s been heartening to see renewed interest in the space program’s past. Neil Armstrong’s death surely had something to do with it, for the scattering of his ashes at sea, which occurred while the 100 Year Starship Symposium was in session, was a reminder of the dramatic days when public fascination with space was intense and the whole world rejoiced at Apollo 11’s success. The memorial ceremony held at the National Cathedral in Washington the day before had focused everyone’s gaze on that great mission, which remained in the air throughout, a continuing counterpoint to formal discussions and casual conversations in the hallways.
Larry Klaes has passed along another historical marker, the fact that today could be called the 60th anniversary of the interplanetary probe. As in so many eventful astronautical moments, the British Interplanetary Society was involved. Eric Burgess and C. A. Cross had come to a BIS meeting in 1952 to read a paper called “The Martian Probe,” which took the concept of an Earth satellite and extended it into a package of instruments that could be sent to Mars. Interestingly, this was at a time when Wernher von Braun was championing the huge manned expeditions that would be written up in Collier’s, along with Chesley Bonestell’s stunning artwork.
The Collier’s series began in March of 1952, and it’s likely that an unmanned probe wouldn’t have caught the eye nearly as well as the Olympian designs of von Braun as rendered by Bonestell’s talented brush. But small, realistic probes were in play in Burgess’ and Cross’ work that would lead to the later successes of Mariner, Venera and Voyager. A message from Paolo Ulivi on the FPSPACE mailing list speculates that it was this paper that began the use of ‘probe’ to refer to unmanned robotic craft. He wonders if this is true and perhaps readers here will know the answer.
If you want to see a bit of history, then, the Burgess and Cross paper appeared in a 1953 issue of the Journal of the British Interplanetary Society (Vol. 12, No. 2), and a subsequent lecture by Cross on ‘probe rockets’ was turned into a 1956 paper in JBIS (Vol. 16, No. 3). We can thus add yet another feather to the cap of BIS, the organization that studied moon landing missions as early as the 1930s and, of course, produced the first detailed study of a starship in Project Daedalus. As most readers of Centauri Dreams already know, JBIS has been at the forefront of interstellar studies for decades and we wish it continued success.
Sentinel in Solar Orbit
In the midst of the reflection on our past comes news from the B612 Foundation of what the organization is calling ‘major support’ from members of the business and financial community. The goal: To build, launch and operate a privately funded deep space mission called Sentinel. What B612 has in mind is placing a space telescope into a solar orbit up to 170 million miles from Earth, giving us a platform for discovering new asteroids and — as befits B612’s purpose — serving as an early warning mechanism for asteroids that could impact our planet.
On announcing the original mission in June of this year, B612’s CEO had this to say:
“The orbits of the inner solar system where Earth lies are populated with a half million asteroids larger than the one that struck Tunguska (June 30, 1908), and yet we’ve identified and mapped only about one percent of these asteroids to date, said Ed Lu, Space Shuttle, Soyuz, and Space Station Astronaut, now Chairman and CEO of the B612 Foundation. “During its 5.5-year mission survey time, Sentinel will discover and track half a million Near Earth Asteroids, creating a dynamic map that will provide the blueprint for future exploration of our Solar System, while protecting the future of humanity on Earth.”
Image: Sentinel’s orbit and field of view. Credit: B612 Foundation.
The organization is saying that in its first weeks of operation, Sentinel will surpass the total of Earth-crossing asteroids catalogued in all previous efforts, and in five years of operation, relaying data to the Deep Space Network, it will track 100 times more asteroids than have been found by all other telescopes combined. The infrared space telescope is being developed at Ball Aerospace by the same team that developed the Spitzer and Kepler space telescopes, with launch aboard a SpaceX Falcon 9 currently planned for 2017-2018. The mission will perform a gravitational slingshot maneuver around Venus before settling into its final orbit around the Sun.
As we enter the age of commercial spaceflight, we can look back to the scientists, engineers and astronauts who made missions like these possible. It would be interesting to know whether Eric Burgess or C. A. Cross would have assumed probes like the ones descended from their model would emerge out of government or from private funding — we can remember the commercial streak in much science fiction of the era, like Heinlein’s “The Man Who Sold the Moon” (1950) in which the first lunar expedition is mounted by a businessman. Whatever the case, their probe ideas continue to resonate as private money now turns to deep space.
Sentinel should go a long way towards protecting Earth from the impact of an unexpected large asteroid strike. It is said that it will be able to detect nearly all of the 50 meter or larger NEA’s. That is approximately the size of the Tunguska event. Meteors less than 25 meters typically burn up in the atmosphere. Many of those are being detected with at least days to week’s notice. So the window of unexpected strikes will become considerably smaller thanks to Sentinel.
Since NEA’s are close to 1 AU orbits, they have more frequent opportunities to take a shot at Earth. So most of the PHAs are NEAs. By knowing the orbits of NEAs, collision paths can typically be calculated decades in advance giving adequate time to slightly nudge them so that they will eventually completely miss the Earth. Otherwise, at a minimum, we could at least know when and where an NEA were going to hit. so, for example, it is often said that, had the Tunguska event struck a few hours earlier it would have destroyed St Petersburg. True, but if the date and location of that happening had been known for decades, years, or even just months, everyone from that city could have been safely evacuated and some of the movable property (e.g. cars) could have been moved as well. Not a good day but at least no one would have died.
However, the discovery of so many NEAs raises the possibility that many of them will have some initial assessment of risk to the Earth. This could introduce quite a lot of confusion and anxiety when we know that most of those threats will turn out not to be a real threat with further observations. But with so many potential threats hitting the news all at once, I could imagine a public push for the development of a deflection program. I just hope that such threats will be handled strictly rationally rather than just assuming the worst- case scenario.
In addition to Sentinel (good thing they didn’t call it Skynet :^)), we might also want to try what Arthur C. Clarke proposed in his 1993 SF novel Hammer of God: Detonate a nuclear bomb deep in the Sol system; the resulting pulse will display every object in our celestial neighborhood.
Here is the short story where the novel came from:
http://www.lightspeedmagazine.com/fiction/the-hammer-of-god/
As I recall, the explosion also caught the attention of some ETI, who sent a reply which oddly enough contained no information, more like a ping.
And while we are transporting nukes into space, let’s start Orion. Note that unlike with Cassini in 1997, I recall no noise over Curiousity’s RTG. Maybe attitudes are finally starting to change regarding nuclear space power. Or at least people have other things to worry about.
The idea that we are just now “entering the age of commercial spaceflight” is I am afraid NASA contractor hype. We entered the age of commercial spaceflight with the birth of the comsat industry in the 1960s. On the other hand, the current efforts being hyped as “commercial” are nothing more than NASA contracts for the traditional von Braunian economic fantasies, quite far from being able to fund themselves through private customers.
http://www.spacedaily.com/reports/Mysterious_Case_of_Asteroid_Oljatos_Magnetic_Disturbance_999.html
Mysterious Case of Asteroid Oljato’s Magnetic Disturbance
by Staff Writers
Madrid, Spain (SPX) Sep 28, 2012
Russell and his team believe that the answer to this discrepancy lies with collisions between Oljato and debris in its orbit.
Back in the 1980s, the arrival of asteroid 2201 Oljato inside the orbit of Venus heralded a flurry of magnetic activity. Now, results from ESA’s Venus Express spacecraft suggest that Oljato has lost its magnetic mojo. Dr. Christopher Russell will present an explanation for Oljato’s strange behavior at the European Planetary Science Congress in Madrid on Tuesday 25th September.
Oljato orbits the Sun once every 3.2 years. During its lifetime, NASA’s Pioneer Venus Orbiter observed three passages of Oljato between Venus and the Sun. Each time, there was a marked increase in the region of unusual magnetic peaks known as Interplanetary Field Enhancements (IFEs), both ahead and behind the asteroid.
Russell said, “This is not typical asteroidal behavior! These magnetic increases are rare, occurring in Venus orbit about 10 times per year. Pioneer observed that when Oljato was just in front or just behind Venus, the rate of IFEs approximately trebled.
“And yet, in more recent observations with Venus Express, the occurrence of IFEs is now lower than the average we find outside this region.”
Russell and his team believe that the answer to this discrepancy lies with collisions between Oljato and debris in its orbit. When objects collide in interplanetary space, they become electrically charged and dust particles are accelerated by the solar wind.
Russell explained, “At one point in time Oljato shed boulders – mostly a few tens of meters in diameter – into its orbit and they formed a debris trail in front and behind Oljato. These impactors then hit other targets as they passed between Venus and the Sun.
“The large amount of fine dust released by these collisions was picked up by the solar wind, producing the IFEs observed by Pioneer, and was accelerated out of the solar system.”
The reduced rate of IFEs observed during the Venus Express epoch suggests that the collisions with Oljato’s co-orbiting material have reduced the general debris in the region as well as the co-orbiting material shed by Oljato.
“The IFEs observed by Pioneer suggest that more than 3 tons of dust was being lost from the region each day. Effects associated with solar heating and gravitational perturbations have gradually nudged larger chunks of debris away from Oljato’s orbit. From once being unusually crowded, the region has become unusually clear and free of IFEs,” said Russell.