Tag Archives: interstellar

100-Year Starship Project

As Voyager 1 embarks on its interstellar voyage, having recently left the confines of our solar system, NASA and the Pentagon are collaborating with the 100-Year Starship Project. This effort aims to make human interstellar travel a reality within the next 100 years. While this is an admirable goal, let’s not forget that the current record holder for fastest man made object — Voyager 1 — would still take around 50,000 years to reach the nearest star to Earth. So NASA had better get its creative juices flowing.

From the Guardian:

It would be hard enough these days to find a human capable of playing a 12-inch LP, let alone an alien. So perhaps it is time for Nasa to update its welcome pack for extraterrestrials.

The agency announced earlier this month that its Voyager 1 probe has left the solar system, becoming the first object to enter interstellar space. On board is a gold-plated record from 1977.

It contains greetings in dozens of languages, sounds such as morse code, a tractor, a kiss, music – from Bach to Chuck Berry – and pictures of life on Earth, including a sperm fertilising an egg, athletes, and the Sydney Opera House.

Now, Jon Lomberg, the original Golden Record design director, has launched a project aiming to persuade Nasa to upload a current snapshot of Earth to one of its future interstellar craft as a sort of space-age message in a bottle.

The New Horizons spacecraft will reach Pluto in 2015, then is expected to leave the solar system in about three decades. The New Horizons Message Initiative wants to create a crowd-sourced “human fingerprint” for extra-terrestrial consumption that can be digitally uploaded to the probe as its journey continues. The message could be modified to reflect changes on Earth as years go by.

With the backing of numerous space experts, Lomberg is orchestrating a petition and fundraising campaign. The first stage will firm up what can be sent in a format that would be easy for aliens to decode; the second will be the online crowd-sourcing of material.

Especially given the remote possibility that the message will ever be read, Lomberg emphasises the benefits to earthlings of starting a debate about how we should introduce ourselves to interplanetary strangers.

“The Voyager record was our best foot forward. We just talked about what we were like on a good day … no wars or famine. It was a sanitised portrait. Should we go warts and all? That is a legitimate discussion that needs to be had,” he said.

“The previous messages were decided by elite groups … Everybody is equally entitled and qualified to do it. If you’re a human on Earth you have a right to decide how you’re presented.”

“Astronauts have said that you step off the Earth and look back and you see things differently. Looking at yourself with a different perspective is always useful. The Golden Record has had a tremendous effect in terms of making people think about the culture in ways they wouldn’t normally do.”

Buoyed by the Voyager news, scientists gathered in Houston last weekend for the annual symposium of the Nasa- and Pentagon-backed 100-Year Starship project, which aims to make human interstellar travel a reality within a century.

“I think it’s an incredible boost. I think it makes it much more plausible,” said Dr Mae Jemison, the group’s principal and the first African-American woman in space. “What it says is that we know we can get to interstellar space. We got to interstellar space with technologies that were developed 40 years ago. There is every reason to suspect that we can create and build vehicles that can go that far, faster.”

Jeff Nosanov, of Nasa’s Jet Propulsion Laboratory, near Los Angeles, hopes to persuade the agency to launch about ten interstellar probes to gather data from a variety of directions. They would be powered by giant sails that harness the sun’s energy, much like a boat on the ocean is propelled by wind. Solar sails are gaining credibility as a realistic way of producing faster spacecraft, given the limitations of existing rocket technology. Nasa is planning to launch a spacecraft with a 13,000 square-foot sail in November next year.

“We have a starship and it’s 36 years old, so that’s really good. This is not as impossible as it sounds. Where the challenge becomes ludicrous and really astounding is the distances from one star to another,” Nosanov said.

Read the entire article here.

Image: USS Enterprise (NCC-1701). Courtesy of Star Trek franchise.

Interstellar Winds of Change

First measured in the early-seventies, the interstellar wind is far from a calm, consistent breeze. Rather, as new detailed measurements show, it’s a blustery, fickle gale.

From ars technica:

Interstellar space—the region between stars in our galaxy—is fairly empty. There are still enough atoms in that space to produce a measurable effect as the Sun orbits the galactic center, however. The flow of these atoms, known as the interstellar wind, provides a way to study interstellar gas, which moves independently of the Sun’s motion.

A new analysis of 40 years of data showed that the interstellar wind has changed direction and speed over time, demonstrating that the environment surrounding the Solar System changes measurably as well. Priscilla Frisch and colleagues compared the results from several spacecraft, both in Earth orbit and interplanetary probes. The different positions and times in which these instruments operated revealed that the interstellar wind has increased slightly in speed. Additional measurements revealed that the flow of atoms has shifted somewhere between 4.4 degrees and 9.2 degrees. Both these results indicate that the Sun is traveling through a changing environment, perhaps one shaped by turbulence in interstellar space.

The properties of the Solar System are dominated by the Sun’s gravity, magnetic field, and the flow of charged particles outward from its surface. However, a small number of electrically neutral particles—mostly light atoms—pass through the Solar System. These particles are part of the local interstellar cloud (LIC), a relatively hot region of space governed by its internal processes.

Neutral helium is the most useful product of the interstellar wind flowing through the Solar System. Helium is abundant, comprising roughly 25 percent of all interstellar atoms. In its electrically neutral form, helium is largely unaffected by magnetic fields, both from the Sun and within the LIC. The present study also considered neutral oxygen and nitrogen atoms, which are far less abundant, but more massive and therefore less strongly jostled even than helium.

When helium atoms flow through the Solar System, their paths are curved by the Sun’s gravity depending on how quickly they are moving. Slower atoms are more strongly affected than faster ones, so the effect is a cone of particle trajectories. The axis of that focusing cone is the dominant direction of the interstellar wind, while the width of the cone indicates how much variation in particle speeds is present, a measure of the speed and turbulence in the LIC.

The interstellar wind was first measured in the 1970s by missions such as the Mariner 10 (which flew by Venus and Mercury) from the United States and the Prognoz 6 satellite from the Soviet Union. More recently, the Ulysses spacecraft in solar orbit, the MESSENGER probe studying Mercury, and the IBEX (Interstellar Boundary EXplorer) mission collected data from several perspectives within the Solar System.

Read the entire article here.

Image: Local interstellar cloud. Courtesy of NASA.

Voyager: A Gift that Keeps on Giving

The little space probe that could — Voyager I — is close to leaving our solar system and entering the relative void of interstellar space. As it does so, from a distance of around 18.4 billion kilometers (today), it continues to send back signals of what it finds. And, surprises continue.

[div class=attrib]From ars technica:[end-div]

Several years ago the Voyager spacecraft neared the edge of the Solar System, where the solar wind and magnetic field started to be influenced by the pressure from the interstellar medium that surrounds them. But the expected breakthrough to interstellar space appeared to be indefinitely put on hold; instead, the particles and magnetic field lines in the area seemed to be sending mixed signals about the Voyagers’ escape. At today’s meeting of the American Geophysical Union, scientists offered an explanation: the durable spacecraft ran into a region that nobody predicted.

The Voyager probes were sent on a grand tour of the outer planets over 35 years ago. After a series of staggeringly successful visits to the planets, the probes shot out beyond the most distant of them toward the edges of the Solar System. Scientists expected that as they neared the edge, we’d see the charge particles of the solar wind changing direction as the interstellar medium alters the direction of the Sun’s magnetic field. But while some aspects of the Voyager’s environment have changed, we’ve not seen any clear indication that it has left the Solar System. The solar wind actually seems to be grinding to a halt.

Today’s announcement clarifies that the confusion was caused by the fact that nature didn’t think much of physicists’ expectations. Instead, there’s an additional region near our Solar System’s boundary that hadn’t been predicted.

Within the Solar System, the environment is dominated by the solar magnetic field and a flow of charged particles sent out by the Sun (called the solar wind). Interstellar space has its own flow of particles in the form of low-energy cosmic rays, which the Sun’s magnetic field deflects away from us. There’s also an interstellar magnetic field with field lines oriented in different directions to our Sun’s.

Researchers expected the Voyagers would reach a relatively clear boundary between the Solar System and interstellar space. The Sun’s magnetic field would first shift directions, then be left behind and the interstellar one would be detected. At the same time, we’d see the loss of the solar wind and start seeing the first low-energy cosmic rays.

As expected, a few years back, the Voyagers reached a region where the interstellar medium forced the Sun’s magnetic field lines to curve north. But the solar wind refused to follow suit. Instead of flowing north, the solar wind slowed to a halt while the cosmic rays were missing in action.

Over the summer, as Voyager 1 approached 122 astronomical units from the Sun, that started to change. Arik Posner of the Voyager team said that, starting in late July, Voyager 1 detected a sudden drop in the presence of particles from the solar wind, which went down by half. At the same time, the first low-energy cosmic rays filtered in. A few days later things returned to normal. A second drop occurred on August 15 and then, on August 28, things underwent a permanent shift. According to Tom Krimigis, particles originating from the Sun dropped by about 1,000-fold. Low-energy cosmic rays rose and stayed elevated.

[div class=attrib]Read the entire article following the jump.[end-div]

[div class=attrib]Image: Voyager II. Courtesy of NASA / JPL.[end-div]