I sometimes imagine Claudio Maccone having a particularly vivid dream, a bright star surrounded by a ring of fire that all but grazes its surface. And from this ring an image begins to form behind him, kilometers wide, dwarfing him and carrying in its pixels the view of a world no one has ever seen. The dream is half visual, half diagrammatic, but it’s all about curving Einsteinian spacetime, so that light flows along the gravity well to be bent into a focus that extends into linear infinity. My slightly poetic vision of what happens beyond 550 AU or so doesn’t do justice to the intrinsic beauty of the mathematics, which Maccone learned to unlock decades ago as he explored the concept of an 'Einstein ring' as fine-tuned by Von Eshleman at Stanford. When I met him (at one of Ed Belbruno’s astrodynamics conferences at Princeton in 2006), we and Greg Matloff and wife C talked about lensing at breakfast one morning. Even then he was afire with the concept. He’d been probing it since the...

My last look at laser communications inside the NASA playbook was a year ago, and for a variety of reasons it's time to catch up with the Laser Communications Relay Demonstration (LCRD), which launched in late 2021, and the projects that will follow. LCRD has now been certified for its mission of shaking out laser systems in terms of effectiveness and potential for relay operations. Ideally, we’d like to receive data from other missions and relay to the ground in a seamless optical network. How close are we to such a result? Image: The Laser Communications Relay Demonstration payload. Credit: NASA Goddard Space Flight Center. LCRD is now in geosynchronous orbit almost 36,000 kilometers above the equator, poised for its two year mission, but before we proceed, note this. The voice is that of Rick Butler, project lead for the LCRD experimenters program at NASA GSFC: “We will start receiving some experiment results almost immediately, while others are long-term and will take time for...

Recent updates to the Deep Space Network have me thinking about the data capabilities of laser communications, and how they will change the way missions operate. In late October, a payload called the Laser Communications Relay Demonstration (LCRD) is scheduled for launch aboard an Atlas V from Cape Canaveral. LCRD will begin its work by receiving radio frequency test signals from the mission operations center and responding with optical signals. Ultimately, the mission should be able to receive data from other missions and relay to the ground. What we have here is NASA’s first technology demonstration of a two-way laser relay system, one that will test laser capabilities to find out, for example, about the potentially disruptive effect of clouds. Because optical signals cannot penetrate them, plans are for LCRD to transmit data from missions to separate ground stations, one in Table Mountain, California and the other at Haleakal? in Hawaii, both chosen because of their low degree of...

NASA's Orbital Test Bed satellite is scheduled for launch via a SpaceX Falcon Heavy on June 22, with live streaming here. Although two dozen satellites from various institutions will be aboard the launch vehicle, the NASA OTB satellite itself houses multiple payloads on a single platform, including a modular solar array and a programmable satellite receiver. The component that's caught my eye, though, is the Deep Space Atomic Clock, a technology demonstrator that points to better navigation in deep space without reliance on Earth-based atomic clocks. Consider current methods of navigation. An accurate reading on a spacecraft's position depends on a measurement of the time it takes for a transmission to flow between a ground station and the vehicle. Collect enough time measurements, converting them to distance, and the spacecraft's trajectory is established. We know how to do atomic clocks well -- consider the US Naval Observatory's use of clocks reliant on the oscillation of atoms in...

We need to improve the way we handle data tracking and deep space navigation. While the near term is always uncertain because of budgetary issues, we can still take the long view and hope that we're going to see a steadily increasing number of robotic and human spacecraft in the Solar System. That puts a strain on our existing facilities, and a premium on any methods we can find to make data return more precise and navigation more autonomous. With these ideas in mind, keep your eye on the Deep Space Atomic Clock (DSAC). It's a NASA technology demonstrator mission being built to validate a miniaturized, ultra-high precision mercury-ion atomic clock that researchers believe will be 100 times more stable than today's best navigation clocks. Managed at the Jet Propulsion Laboratory, the DSAC has been tweaked and improved to the point where it allows drift of no more than a single nanosecond in ten days. Image: Drawing of the DSAC mercury-ion trap showing the traps and the titanium vacuum...

Best wishes for the New Year! I got a resigned chuckle -- not a very mirthful one, to be sure -- out of a recent email from Adam Crowl, who wrote: "Look at that date! Who imagined we'd still be stuck in LEO in 2014???" Indeed. It's hard to imagine there really was a time when the 'schedule' set by 2001: A Space Odyssey seemed about right. Mars at some point in the 80's, and Jupiter by the turn of the century, a steady progression outward that, of course, never happened. The interstellar community hopes eventually to reawaken those dreams. Yesterday's post on laser communications makes the point as well as any that incremental progress is being made, even if at an often frustrating pace. We need laser capabilities to take the burden off a highly overloaded Deep Space Network and drastically improve our data transfer and networking capabilities in space. The Lunar Laser Communication Demonstration (LLCD) equipment aboard the LADEE spacecraft transmitted data from lunar orbit to Earth...

A recent email from Centauri Dreams regular Carl Keller reminded me about the laser communications tests conducted aboard a NASA satellite. The Lunar Atmosphere and Dust Environment Explorer satellite (LADEE) carried a laser package that demonstrated excellent download and upload rates and successful transmission of two simultaneous channels carrying high-definition video streams to and from the Moon. The fast transmission of large data files shows how useful laser methods will become. Image: NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) observatory launches aboard the Minotaur V rocket from the Mid-Atlantic Regional Spaceport (MARS) at NASA's Wallops Flight Facility, Friday, Sept. 6, 2013, in Virginia. Image Credit: NASA/Clara Cioffi. All this is heartening because we need better communications as we begin to build a true infrastructure in the Solar System, while the demands of interstellar communication we'll eventually need for probes of other stars are even more...

Greg Egan, a jewel in Australia's science fiction crown, writes in his 1997 novel Diaspora about a mind-bending far future scenario for interstellar travel. The human race has split into those still in biological bodies, those embedded in humanoid robots, and those who choose to live as software running on central computers. I won't get into the rich details of the novel this morning, but suffice it to say that the diaspora portrayed here involves a thousand clones of a future Earth community sent to explore nearby stars. Different digitized copies of the same characters spin out their own story lines over a background that spans hundreds of light years. This is one way to get to the stars, reminiscent of Robert Freitas' nanotech probes that house thousands of human intelligences in spacecraft no larger than needles. It's a reminder that highly advanced future cultures may have means at their disposal for star travel even if we find no way of getting up to more than a small...

Tracking spacecraft from Earth is an increasingly cumbersome issue as we continue to add new vehicles into the mix. The Deep Space Network can track a Voyager at the edge of the Solar System, but using round-trip times and the Doppler shift of the signal is a less than optimal solution for accurate tracking. What we'd like is a method that would allow the spacecraft to calculate its position on its own, taking precise readings from some system of celestial markers. Pulsars have been in the mix in this thinking for some time. After all, these remnants of stars rotate at high speed and put out radiation beams that blink on and off at regular intervals. They've been called 'celestial lighthouses' because of this effect, and they're usefully consistent, producing their pulses in intervals that vary from milliseconds to seconds. The easiest analogy is with the global positioning system, and in this recent article in IEEE Spectrum (thanks to Frank Smith for the pointer), that's exactly how...

Back when I was working on my Centauri Dreams book, JPL's James Lesh told me that the right way to do communications from Alpha Centauri was to use a laser. The problem is simple enough: Radio signals fall off in intensity with the square of their distance, so that a spacecraft twice as far from Earth as another sends back a signal with four times less the strength. Translate that into deep space terms and you've got a problem. Voyager puts out a 23-watt signal that has now spread to over one thousand times the diameter of the Earth. And we're talking about a signal 20 billion times less powerful than the power to run a digital wristwatch. Now imagine being in Alpha Centauri space and radiating back a radio signal that is 81,000,000 times weaker than what Voyager 2 sent back from Neptune. But lasers can help in a major way. Dispersion of the signal is negligible compared to radio, and optical signals can carry more information. Lesh is not a propulsion man so he leaves the problem of...

In a world of search engines, GPS and always-on connectivity, I sometimes wonder what's happening to serendipity. Over the years, I've made some of my best library finds by browsing the stacks, just taking some time off and walking around scanning the book titles. Odd ideas show up, mental connections get forged, and new insights emerge. Targeted searching is generally what we do (think Google), but never forget the value of the odd juxtaposition that comes from random wanderings. Too much targeting can produce tunnel vision. For that matter, have you noticed how hard it is to get lost these days? I'm just back from Oakland, where Marc Millis and I went for interviews with the History Channel in the gorgeous setting of Chabot Space & Science Center in the hills above the city. The view on the drive up was spectacular, and my guide used an iPad to continually update our position on the map, so getting lost was impossible. My son Miles drove up from his home south of San Francisco and...

The news that a message has been sent using a beam of neutrinos awakened a flood of memories. Back in the late 1970s I was involved with the Society for Amateur Radio Astronomers, mostly as an interested onlooker rather than as an active equipment builder. Through SARA’s journal I learned about Cosmic Search, a magazine that ran from 1979 through 1982 specializing in SETI and related issues. I acquired the entire set, and went through all 13 issues again and again. I was writing sporadically about SETI then for Glenn Hauser’s Review of International Broadcasting and later, for the SARA journal itself. Cosmic Search is a wonderful SETI resource despite its age, and the recent neutrino news out of Fermilab took me right back to a piece in its third issue by Jay Pasachoff and Marc Kutner on the question of using neutrinos for interstellar communications. Neutrinos are hard to manipulate because they hardly ever interact with other matter. On the average, neutrinos can penetrate four...

You would think that Internet pioneer Vint Cerf would be too busy with the upcoming transition from Internet Protocol version 4 to IPv6 -- not to mention his other duties as Google's Chief Internet Evangelist -- to keep an eye on space communications. But the man behind the Net's TCP/IP protocols never lets the human future off-planet get too far from his thoughts. These days the long hours he has already spent on developing a new methodology that lets us network not just Earth-based PCs but far-flung spacecraft have begun to pay off. 2011 should be a banner year for what many have already begun to call the InterPlanetary Internet. At issue is a key problem with the way the Internet works. TCP/IP stands for Transmission Control Protocol/Internet Protocol, and it describes a method by which data are broken into small data envelopes and labeled for routing through the network. When they reach their destination, the packets are then reassembled. We know how the Net that grew out of...

We've seen some remarkable feats of celestial navigation lately, not the least of which has been the flyby of comet Hartley 2 by the EPOXI mission. But as we continue our push out into the Solar System, we're going to run into the natural limits of our navigation methods. The Deep Space Network can track a spacecraft from the ground and achieve the kind of phenomenal accuracy that can thread a Cassini probe through a gap in the rings of Saturn. But positional errors grow with distance, and can mount up to 4 kilometers per AU of distance from the Earth. To go beyond the Solar System, we'll need a method that works independently, without the need for ground station assistance. Pulsar navigation is one way around the problem. Imagine a spacecraft equipped with a radio telescope that can determine its position by analyzing the signals from distant pulsars. These super-dense remnants of stellar explosions emit a beam of electromagnetic radiation that is extremely regular, and as we've...

If we can get the right kind of equipment to the Sun's gravitational focus, remarkable astronomical observations should follow. We've looked at the possibilities of using this tremendous natural lens to get close-up images of nearby exoplanets and other targets, but in a paper delivered at the International Astronautical Congress in Daejeon, South Korea in October, Claudio Maccone took the lensing mission a step further. For in addition to imaging, we can also use the lens for communications. The communications problem is thorny, and when I talked to JPL's James Lesh about it in terms of a Centauri probe, he told me that a laser-based design he had worked up would require a three-meter telescope slightly larger than Hubble to serve as the transmitting aperture. Laser communications in such a setup are workable, but getting a payload-starved probe to incorporate a system this large would only add to our propulsion frustrations. The gravitational lens, on the other hand, could serve up...

If we can use GPS satellites to find out where we are on Earth, why not turn to the same principle for navigation in space? The idea has a certain currency -- I remember running into it in John Mauldin's mammoth (and hard to find) Prospects for Interstellar Travel (AIAA/Univelt, 1992) some years back. But it was only a note in Mauldin's 'astrogation' chapter, which also discussed 'marker' stars like Rigel (Beta Orionis) and Antares (Alpha Scorpii) and detailed the problems deep space navigators would face. The European Space Agency's Ariadna initiative studied pulsar navigation relying on millisecond pulsars, rotating neutron stars that spin faster than 40 revolutions per second. The pitch here is that pulsars that fit this description are old and thus quite regular in their rotation. Their pulses, in other words, can be used as exquisitely accurate timing mechanisms. You can have a look at ESA's "Feasibility study for a spacecraft navigation system relying on pulsar timing...

Networking deep space should be a priority for future missions. If we can set up robust networking between spacecraft, we relieve the Deep Space Network of a huge burden, that of having to communicate directly with each spacecraft for tasks that are essentially routine. No more maneuvering huge dishes to catch one fleeting signal, at least not for missions to come. Instead, we could rely on spacecraft to create their own file transfers, move their own traffic to astronauts (remember the video mail in 2001: A Space Odyssey?), and manage local operations. Why not use the Internet we've already got? Unfortunately, the TCP/IP (Transmission Control Protocol/Internet Protocol) tools we use today are 'chatty,' a term that means the computers that run them exchange data over and over again through the course of a transaction. Suppose you want to send a file through FTP (File Transfer Protocol). Doing so takes eight round trips of data between the computers involved before the file can be...

Bringing computer networking to space exploration is a major step forward. It allows us to go beyond the old model of pointing radio dishes at a specific spacecraft and downloading information -- a time-consuming process as we move from one spacecraft to another -- to communicate instead with a single hub vehicle that could be processing data from a cluster of sources. That maximizes precious communications resources here on Earth and allows us to connect planetary rovers, for example, with base stations, orbiting spacecraft and other nearby vehicles. We've talked about interplanetary networking before in terms of the InterPlanetary Internet Project (IPN), a key player in which is Internet legend Vinton Cerf. But extend the idea further, as John Barker (University of Glasgow) is doing today at the Royal Astronomical Society's national meeting in Lancashire (UK). What Barker has in mind is using 'smart dust' -- tiny computer chips surrounded by a polymer sheath -- to form intelligent...