Voyager. The Longest Journey

Today is the 40th anniversary of the launch of the Voyager 1 spacecraft. On September the fifth in 1997 a Titan 3-C rocket took off from Kennedy Space Center carrying a 773 kilo spacecraft that has completely changed the way we see our solar system and even now is exploring the space between the stars themselves. How many things do you know of that are still working after 40 years. The picture below shows Voyager and the various parts of the spacecraft.

Voyage Spacecraft (Credit: NASA)

The original concept for the Voyager missions was to be a ‘Grand Tour’ of the outer solar system with flybys of four planets Jupiter, Saturn, Uranus and Neptune. Indeed, the Voyager 2 spacecraft did succeed in visiting them all giving us our first close up view of Uranus and Neptune.

The discoveries made by these two robot explorers are too numerous to mention. I can only mention a few: Jupiter’s Rings, volcanoes on Io, the ice covering on Europa, shepherd moons in Saturn’s rings, the dense hydrocarbon atmosphere of Titan, the broken moon Miranda of Uranus and the great black spot on Neptune. Before Voyager all of these places were at best hazy smudges in a telescope, it was Voyage that turned them into worlds for us. The mosaic picture below shows some of the images taken by the Voyager spacecraft.

Mosaic of Voyager Images (Credit: Don Davis, NASA)

Because their mission was planned to take them on a journey so far from the Sun the Voyagers could not be powered by solar cells as most spacecraft are. Instead, each of the two probes carries three Radioisotope-Thermoelectric-Generators (RTGs). RTGs are basically a rod of radioactive material surrounded by thermocouples that convert the heat into electricity. the three generators combined produced a combined 470 watts of power at launch and even today after 40 years they are still generating about half that amount. That is still enough power to enable the Voyager probes to remain in contact with Earth although most of the probe’s instruments, such as the cameras, have been turned off to conserve power. Only the magnetometer and the low and high energy particle detectors continue to operate, continue to give us information about the space through which Voyager still journeys.

Today Voyager 1 has entered interstellar space, the first object made by mankind to do so. When the Voyagers were launched 40 years ago no one had any idea what the edge of the solar system would be like let alone where it might be. It was Voyager 1 who showed how the solar wind, pushing out from the Sun, comes to a pause known as the heliopause. Beyond that the low energy particles from the Sun disappear while the magnetic field shifts to that of the Milky Way.

Voyager 1 entered interstellar space in August of 2012 and Voyager 2 will soon join it. NASA estimates that the power sources on the spacecraft will allow them to remain in contact with Earth until sometime around 2030.

When that contact is lost the long mission of these explorers will finally be over, but only for human beings! You see the scientists and engineers who built Voyager knew that their creation could travel between the stars for thousands if not millions of years and there was the remote but still exciting possibility that one of the Voyagers might someday be found by non-human intelligences.

So the men who built Voyager included a greeting to any aliens that might find it. A golden record was stored away in the Voyager spacecraft. This record contained some of the sounds of Earth, music and greetings, along with images of life on Earth. The cover protecting the record has instructions for playing the record and even a stylus to be used in the playback. It is possible that the messages sent on Voyager may one day be the only record of our ever existing!

In 40,000 years Voyager 1 will pass about 1.6 light years from the star Gliese 445 while at the same time Voyager 2 will pass about 1.7 light years away from the star Ross 248 (both are red dwarf type stars). Even then the Voyagers will continue on and where their journey will end no one can say.

As of this morning Voyager 1 was 20,884,724,316 kilometers from the Sun and getting 16.995 kilometers further every second. Voyager 2 was 17,178,385,861 from the Sun and moving at a velocity of 15.374 kps.

If you’d like to know more about the Voyager spacecraft NASA has two websites. The first deals with the entire voyager mission while the second is for ‘Voyager the Interstellar Mission’. Click on the links below to be taken to those sites.

https://www.nasa.gov/mission_pages/voyager/index.html

https://voyager.jpl.nasa.gov/

Space News for August 2017

There were some interesting news stories related to the exploration of space over the last month reaching from right here on Earth to the very limits of the observable Universe. I’ll start with some news that is both shocking and saddening about the legacy of the first man to walk on the Moon, Neil Armstrong.

In Armstrong’s hometown of Wapakoneta, Ohio there is the Neil Armstrong Air and Space museum. The museum was built by the State of Ohio as a place to honor Armstrong’s achievements and display for the public some of artifacts and tributes that were bestowed on the astronaut during his career. I’ve been there, it’s a wonderful little museum where you can learn about, or remember as the case may be, the early days of space exploration. I highly recommend it if you’re anywhere near northwestern Ohio.

Now on the night of Friday the 31st of July the museum was broken into and robbed by what authorities believe were three or four men. A number of exhibits were stolen including rare medals and coins but the most valuable item that was taken was a solid gold miniature model of the Lunar Module Eagle presented to Armstrong upon his return to Earth after his Moon landing.

Local police hope to recover the stolen items but right now they have no idea who the burglars were. The scariest thing is that the gold LM model could be melted down for the gold so that no one would ever know what it once was. Anyway it’s a sorry comment on our time that money and greed should in any degree tarnish the legacy of the greatest achievement in human history. The photo below shows Michael Collins’s model of the stolen LM replica.

LEM Replica (Credit: Nick Welsh)

My second story concerns our picture of the entire observable Universe and how much we’ve learned about it. A new study called the ‘Dark Energy Survey’ (DES) has released some very detailed results of the structure and distribution of matter in the Universe along with how the structure and distribution have changed over the past seven billion years.

The DES team employed a technique called gravitational lensing, a phenomenon first predicted in Einstein’s General Theory where the light from a distant object can be bent by the gravitational field of a closer object. This technique can be used to measure the mass of the closer object by how much it bends the light of the distant object. Using this technique 26 million galaxies, that’s right 26 million galaxies, had their mass measured allowing a map to be made of the mass distribution in a large section of the Universe, see photo below.

Mass Distribution in the Universe (Credit: Chihway Chang, DES Collaboration)

In previous posts (25Sept16 and 3Dec16) I have mentioned the Cosmic Microwave Background (CMB), the leftover heat of the Big Bang which gives us a ‘baby picture’ of our Universe about 380,000 years after the Big Bang. So with the addition of the new DES study we can now test our theoretical models of cosmic evolution. In other words, taking the CMB measurements as the initial conditions do our models give us the kind of Universe we see in the DES?

It turns out that the simplest model; known as Lambda-Cold Dark Matter (λ-CDM) is still an excellent fit. In the model the Dark Energy accelerating the expansion of the Universe is just a constant term (Einstein used the Greek letter λ in his equations) and the Dark Matter we can measure only by its gravity it composed of heavy particles of some kind.

This is a rather strange state of affairs. We don’t know what 95% of the Universe is (Dark Energy, Dark Matter) but when it comes to predicting how it behaves we’re spot on!

Finally, you may have heard that NASA has a job opening for a new Planetary Protection Officer. No, we’re not talking about fighting off the aliens, at least not with a ray gun. NASA has had a Planetary Protection Officer ever since the days of Apollo when there was a very real concern that Lunar microbes might be able to hitch a ride to Earth with our astronauts.

Today most of the Planetary Protection Officer’s job actually deals with protecting other planets, such as making certain that Earth bacteria don’t use one of our Mars Rovers to contaminate the planet before we can discover whether or not life originated there. (Imagine the first astronauts on Mars discover life!!!! Oh wait; it’s just a staphylococcus infection.)

Now if you think Planetary Protection Officer sounds like a fun job, well nine-year-old Jack Davis of New Jersey thought so to. He applied for the job in a hand written note which includes as a qualification “My sister thinks I’m an alien”. Anyway, Jack got a nice reply from NASA’s Director of Planetary Science Doctor James Green telling him to study hard and one day he can work for NASA. Hopefully one day he will.

 

Space News for May 2017

I guess the big news in space for this month is NASA’s decision that the Exploratory Mission 1 (EM1) will be unmanned as was originally planned. NASA had been asked by President Trump to consider the possibility of adding a crew to the first launch of the long awaited Space Launch System (SLS) along with the Orion spacecraft.

Space Launch System (Credit NASA)

In the end NASA decided to stick to the original mission plan in part because of the added costs in preparing the spacecraft for a crew (Estimated at between 600 and 900 million). Just as importantly however, was NASA’s desire to push the spacecraft to its limits on this first mission, something they did not feel comfortable doing with a live crew. In announcing their decision NASA also stated that the schedule for the EM1 mission will slip into early 2019!

This delay means that the scheduled first manned launch of the SLS/Orion will now take place no earlier that mid 2021 and you can expect that date to slip as well. If you’d like to read NASA’s official announcement click on the link below.

https://www.nasa.gov/feature/nasa-affirms-plan-for-first-mission-of-sls-orion

This decision by NASA means that the return of manned launches to Kennedy Space Center will now undoubtedly be by a commercial space company, either Space X’s Dragon capsule of Boeing’s Starliner. Both of these two companies hope to begin manned missions to the International Space Station  (ISS) late next year but you can expect one or both to slip into 2019.

Speaking of Space X just a couple of days ago Elon Musk’s company successfully launched the fourth satellite in the Inmarsat series. Inmarsat is a network of satellites built by Boeing to provide broadband connections for aircraft, ships at sea and mobile land users. This was Space X’s second successful launch in as many weeks but the notable fact about this launch was that Space X did not try to recover the rocket’s first stage! The Inmarsat satellite is so massive that the Falcon 9 rocket needed every bit of fuel to put it into orbit leaving nothing left for a recovery.

Inmarsat Satellite (Credit Boeing)

This says something of the sophistication of Space X’s technology that a mission where they do not recover the rocket is newsworthy.

In other news the Cassini spacecraft has continued to send back breathtaking images of the planet Saturn and it’s rings. Nothing really dramatic has happened to Cassini I just love those pictures!

Saturn-Mosaic (Credit NASA)

Also there was a bit of amusing news coming from the ISS as astronauts got to enjoy eating some fresh vegetables courtesy of crew member Peggy Whitson. Astronaut Whitson has harvested the first crop of Chinese Cabbage grown in the microgravity of space. This is the fifth vegetable to be grown aboard the ISS and more are planned in the future.

Cabbage in Space (Credit NASA)

These first attempts at farming in space may just be experiments to see what is and what isn’t possible but in the long run our ability to produce food on the Moon or Mars or wherever will determine if humanity actually has a future in space.

 

 

 

 

More Space News for April

Two days ago NASA held a press conference to announce some of the results that scientists have discovered from the Cassini spacecraft. Cassini is in orbit around the planet Saturn and is in the final few months of it’s twenty year long mission.

Cassini orbiting Saturn

The press conference mainly dealt with some new discoveries about Saturn’s moon Enceladus which we knew from earlier observations was an ice covered world similar to Jupiter’s moon Europa. For several years now NASA astronomers have speculated that, again like Europa, Enceladus might have a liquid ocean beneath the ice covering, an ocean that could support life.

Now the heat energy that keeps the ocean warm would come from the flexing and squeezing of the moon’s interior caused by the interacting gravitational fields of Saturn and it’s other moon’s, the tidal pulls. The same process is known to cause the numerous volcanoes on Jupiter’s moon Io and are suspected to keep the ocean on Europa warm. The heat generated by this process could also provide the energy for life on Enceladus.

Images taken of Enceladus by Cassini have discovered plumes of water spewing out of the Moon like geysers and now Cassini has even succeeded in flying through those plumes and identifying some of the chemicals contained in them. In their announcement NASA scientists stated that Cassini has detected considerable amounts of both Carbon Dioxide and Methane both of which are commonly associated with living processes. The image below details the processes going on at the moon.

Enceladus Geothermal Processes

These results give us another possible home for life in our Solar system. Along with Mars and Europa, Enceladus is another world we need to explore further. A specialized mission to search for life on Enceladus may take years to develop and launch however, but someday we’ll know whether or not we have close neighbors living around the ringed planet.

If you’d like to read more about NASA’s announcement click on the link below.

https://www.nasa.gov/press-release/nasa-missions-provide-new-insights-into-ocean-worlds-in-our-solar-system

There has also been another announcement from NASA concerning grant money being funded to a series of new technology programs. These grants are called the NASA Innovative Advanced Concept or NIAC program and are intended to study possible future technologies for spaceflight. The initial Phase I grants are about $125,000 dollars while Phase II grants can be as much as a half a million dollars.

The Phase I grants can be very interesting, even far out concepts while the Phase II grants tend to be a bit more realistic. In the Phase I group are included four completely new type of propulsion technologies, two are intended for interstellar travel, along with  a ‘vacuum balloon’ to drift over the surface of Mars and  Solar Surfing!

The Phase II grants include a probe of the interior of the planet Venus and a fusion enabled Pluto orbiter and lander. If you’d like to read a bit more about these possible future space technologies click on the link below.

https://www.nasa.gov/directorates/spacetech/niac/2017_Phase_I_Phase_II

There’s always something new happening in space so I hope you’ll be coming back soon.

 

 

NASA at a Crossroads. On to Mars or back to the Moon.

Over the last four presidential administrations NASA’s long term goals for human spaceflight have been pulled back and forth so drastically it almost appears as if we’ve been going backward rather than forward. While Bush#1 wanted to go to Mars, Bill Clinton said let’s build the Space Station that Ronald Reagan called for (at least that actually got done). Then Bush#2 said let’s go back to the Moon while Obama only suggested going to a near Earth asteroid as a stepping stone to Mars.

Now we have a new administration, one who seems to have even less of a plan for space than the ones I’ve just mentioned, so I’m gonna give’em one.

Of course my heart says Mars. I was fourteen years old when Apollo 11 landed on the Moon and I can’t accept that we haven’t already gotten to Mars. I desperately hope that we will reach Mars during my lifetime so my heart says Mars!

My head says back to the Moon and here are my reasons why. Next year NASA will launch it’s first Space-Launch-System/Orion capsule mission and there is now talk of making that first mission a manned mission. Now the SLS launch vehicle is really just a modified version of the Ares V rocket that was conceived as a part of Bush#2’s ‘Constellation Program’ for going back to the Moon, and the Orion capsule isn’t even modified as far as I know. So, late next year we could very likely have two of the three major systems for a Moon landing. All we’d need is the lander and if NASA were given the direction and funding that could be accomplished in six years or so. The pictures below show the original Constellation Program ‘Parts’ and the, almost completed SLS-Orion for comparison.

NASA Constellation Program

 

Space Launch System

The resemblance is obvious. Again all we need to get back to the Moon is the Altair lander shown below or a similar lander.

Altair Lander

To go to Mars however, we would be starting from scratch. The idea of the Orion capsule taking anybody all the way to Mars is ludicrous. Not only doesn’t the combined SLS-Orion have the delta vee necessary for a Hohmann orbit  to Mars (that’s the lowest energy required transfer orbit), but there’s no way for three or four astronauts to be stuck inside the small Orion capsule for the more than a year long journey to Mars.

To go to Mars we need a Spaceship, a real one. Maybe not as fancy as the Hermes in the Martian or Discovery in 2001 but still an actual spaceship! And then when we get into Mars orbit we’re going to need a lander to get down to the surface, and even before we send that spaceship everybody always assumes that there will be supplies ‘pre-positioned’ on the surface of Mars awaiting the astronauts. None of this equipment is anywhere past the drawing board, there is absolutely no hardware existing or in the process of construction or even funded. Nothing.

I have a few more reasons for recommending the Moon. As I mentioned above, NASA is studying the concept of pre-positioning equipment and supplies before astronauts land on a planet or satellite. Well we could practice that technique on the Moon a lot more cheaply than trying it on Mars. Indeed, the Moon could be a practice range for landing a big rover, a habitat module, working out regular resupply missions and lot of the techniques needed for a Mars mission could be learned on the Moon.

It’s often been said that the Moon can serve as a stepping stone to Mars and since we’re almost equipped to do that let’s just do it.

The chaotic politics of the last 30 years has resulted in a complete lack of direct in NASA’s goals for human spaceflight. If the current administration were to authorize NASA to build a lander, and provide adequate funding, we could actually accomplish something in just a few years. We could at least get back to where we were when I was a teenager.

I’m not holding my breath!

 

 

NASA Selects two new deep space missions to Asteroids. Meet Lucy and Psyche

Two days ago on January the 4th, NASA selected two new missions as a part of their discovery program for the exploration of deep space, away from Earth orbit that is. The new missions are named Lucy and Psyche and will carry out detailed examinations of a range of asteroids not yet studied. To read NASA’s announcement of the missions click the link below.

https://www.nasa.gov/press-release/nasa-selects-two-missions-to-explore-the-early-solar-system

NASA Deep Space Missions. Lucy (Left) and Psyche

Since I’m more interested in the Lucy mission I’ll talk about Psyche first. The Psyche spacecraft will travel to the unusual asteroid 16Psyche. The thing that makes 16Psyche so different, from measurements made here on Earth, is that it has a much higher content of Iron and Nickel than the asteroids we visited so far. In fact it looks a great deal like what we believe the core of our own planet is.

Astronomers have for over a hundred years speculated that the asteroid belt is actually another planet that failed to form because of the gravitational effects of massive Jupiter next door. If so then 16Psyche may be the core of that failed planet and by studying it we may learn something about how planets form as well as something about the core of our Earth.

On the other hand the Lucy mission intends to visit no less than seven different asteroids in the areas of space know as the Jupiter Trojan positions. The Trojan positions have always fascinated me; they are in fact the only stable three body solutions to Newton’s equations of planetary motion Solutions that were discovered by the French mathematician Joseph-Louis LaGrange in his search for a general solution to the “Three Body Problem”.

You see, although when Newton’s laws are applied to a star and a single planet they quickly lead to a nice simple function as a solution, when you add in the gravitational effect of a second planet, a third body, there is in general analytic no solution. After Newton’s death LaGrange and other mathematicians searched for solutions to the three body problem and even today there is work being done on the problem.

So, if there is no general solution how do astronomers calculate when an eclipse will occur, or when a comet will appear in the sky or how did they calculate the trajectory of the Voyager 2 spacecraft as it went past four planets. Well you do it a tiny bit at a time, over and over again.

This was an assignment I had to do in Graduate school. You see, if you know the positions and momentum of the planets today you can calculate what their positions will be, let’s say tomorrow. Then, using Newton’s laws of Gravity, you calculate how their new positions change their momentum. Then you just repeat the whole process over and over again.

This is the sort of calculations that computers are good at, that’s how I did it in Grad school. But back in LaGrange’s day a person had to do all that arithmetic and it would take years! My hat is off to those gentlemen.

Monsieur LaGrange was able to find five particular solutions to the problem (See Picture Below) and these are know as LaGrangian points in his honor. But only two of these positions are stable, L4 and L5 and these have become known as the Trojan positions because Jupiter has acquired a number of asteroids at it’s L4 and L5 positions. Asteroids which have been named for characters in Homer’s Iliad with L4 being the Greek camp and L5 being the Trojan camp.

LaGrange Points

Getting back to the Lucy mission. Expected to launch in 2021 Lucy will flyby the main asteroid belt member 1981EQ5 in 2025 on it’s way to the Greek camp (L4) where it will encounter four different asteroids in 2027 and 2028. Lucy will then loop back around Earth before headed back to the Trojan camp (L5) for a final encounter with the dual asteroid Patroclus/Menoetius in 2033. This is going to make Lucy one of the longest and certainly most complex missions ever attempted. A lot to look forward to in the years ahead.