Signals from the Far Side of the Moon

China’s Chang’e-4 spacecraft made the first ever soft-landing on the far side of the moon  on Wednesday Jan 2nd, 2019. The far side of the moon never faces the Earth so radio signals are blocked by bulk of the moon. How do the Chinese communicate with their spacecraft and lander? They use a relay satellite that is parked in space on the opposite side of the Moon from Earth.

The  relay satellite “Queqiao” was launched in May 2018, months before  Chang’e-4 launch in December. It now sits in what is known as the L2 Lagrange point of the Earth-Moon system. In the 1700s, the mathematicians Euler and Lagrange discover 5 points where the combined gravitational forces of two larger bodies (in this case the Earth and the Moon) create a small area of gravitational stability.  A smaller body (such as a relay satellite) at one of these points can maintain a stable or nearly stable position relative to the large bodies. There are five Lagrangian points but the L2 Lagrangian point is located directly opposite the Earth from the Moon.

Image of Earth Moon Lagrangian Points
Earth-Moon Lagrangian Points

Parking the relay satellite Queqiao at the L2 point means that it always stays at the same relative position, lined up with the Earth and Moon, as the Moon orbits the Earth and as the Earth-Moon system orbits the Sun.  Queqiao is the first communications satellite to utilize this L2 point.

Animation of the relative positions of the Lagrangian points in a two body system.
Animation of the relative position of Lagrangian points in a two body system.

A normal mission to lunar orbit usually takes four or five days, but Queqiao took longer to reach its special orbit at the L2 point.

Image of How the Chinese Relay Satellite Reach the L2 point
How the Chinese Relay Satellite Reach the L2 point

Along the way, Queqiao deployed two micro-satellites called Longjiang-1 and 2 that were to enter lunar orbit. Unfortunately, only Longjiang-2 was successful in the braking maneuver required to reach lunar orbit.

Image of The Earth as seen from Longjiang-2, with Petropavlovskiy crater in the foreground.age of
The Earth as seen from Longjiang-2, with Petropavlovskiy crater, on the far side of the Moon, in the foreground.

 

Ultima Thule Flyby on New Year’s Eve

NASA’s New Horizons spacecraft will welcome the New Year with a flypast of the most distant solar system object ever visited. New Horizons made headlines when it flew past Pluto and Charon in 2015 and is now headed for a rendezvous with the Kupier Belt object  “Ultima Thule”.

Here are 19 facts about this encounter to start the year 2019.

  1. The closet approach is predicted to occur at 09:33 PM on Dec 31st, 2018 PST.
  2. Ultima Thule was discovered in 2014, 8  years after the launch of the New Horizons spacecraft.
  3. Ultima Thule is approximately 37 km across, about the same distance as a drive from Point Grey to Coquitlam.
  4. At its closet approach, New Horizon is expected to be  3,500 km from Ultima Thule. This is 3 times closer than it was to Pluto and should result in higher resolution images and spectroscopic data.
  5. Signals from Ultima Thule take about 6 hours to reach Earth
  6. Ultima Thule formed in middle of the Kupier Belt where temperatures are close to absolute zero and it is too small to have a geologic engine like Pluto. Hence, scientists expect it to be a  well-preserved sample of a planetary building block.
  7. The first health status signal is expected to be received around 07:00 am PST on Jan 1st with the first image data coming in a few hours later. Look for the first images to be released on Jan 2nd, 2019.
  8. New Horizons will collect about 50 GB of data during its flypast but it will take about 20 months to send all that data back to Earth.
  9. Analysis of recent light curves haven’t revealed the variations predicted by previous observations. Alan Stern, the principle investigator, has called this discrepency “Ultima Thule’s first puzzle”.
  10. The orbit of Ultima Thule was not well established so New Horizons has been imaging it and has made several course correction maneuvers to adjust for differences in its predicted position vs its actual position. The last correction was a short 27 second burn on Dec 20th, 2018.
  11. New Horizons entered “Encounter Mode” on Boxing Day so its on-board software will now handle any problems without intervention from Earth.
  12. A Hazards Team scoured images for signs of moons or other dangerous debris along New Horizons’ path but gave the “all clear” signal in December 2018 for a close flyby.
  13. Ultima Thule may be shaped like a rubber ducky or possibly two separate bodies based on observations made during its occultation of a star in 2017.
  14. Ultima Thule’s official designation is  2014 MU69.
  15. The apparent magnitude of Ultima Thule is 27: too faint for all but the most powerful telescopes.
  16. The name “Ultima Thule” was nominated by about 40 people in a public campaign for selecting a nickname. It refers to a distant place located beyond the borders of the known world.
  17. Ultima Thule orbits the Sun once every 295 years.
  18. Ultima Thule is not visible in the night sky on Dec 31st as it is located in the constellation Sagistarius and will be less than  5° from the Sun.
  19. It will reach naked eye brightness (magnitude 6) as seen from New Horizons’ point of view 3-4 hours before closest approach.
New Horizons Ultima Thule Encounter Timeline

For more information on the New Horizons mission, including fact sheets, schedules, video and images, visit: http://www.nasa.gov/newhorizons and http://pluto.jhuapl.edu.

Full Moon Trapped in the Winter Hexagon

This Saturday, a full moon is trapped within the six bright stars that make up the huge asterism known as the Winter Hexagon. Asterisms are easily identifiable patterns of stars, like constellations, but they are not recognized by the International Astronomical Union. Asterisms may be a part of a constellation (like the big dipper), or can be composed of stars from different constellations as is the case with the Winter Hexagon.

Sky chart for the Winter Hexagon
The Winter Hexagon encircling the full Moon on Dec 22nd at midnight as seen from Vancouver.

The six stars that make up the Winter Hexagon include some of the brightest stars in our sky; five of the six are among the top-10 brightest stars visible from the northern hemisphere. Here is a summary along with each star’s visual magnitude.

  • Capella (+0.07), the fourth brightest star in our sky, was the discovered to be a binary in 1899 based on spectroscopy. Photographic plates displayed two superimposed spectrums with different Doppler shifts. This revealed two components that were periodically moving towards and away from Earth and thus orbiting each other.
  • Aldebaran (+0.99) marks the red eye of Taurus the bull. It is the ninth brightest star. It lies close enough to the ecliptic to be occulted by the Moon. In about two million years, NASA’s Pioneer 10 spacecraft will make a fly past of Aldebaran.
  • Rigel (+0.28) is the fifth brightest star in our sky, but it is designated β Orionis because the variable red giant  Betelgeuse (α Orionis) is occasionally brighter. Rigel is a blue-white super giant that shines with the luminosity of 40,000 Suns.
  • Sirius (-1.44), commonly called the “dog star”,  is the brightest star in the sky and is twice as bright as the next brightest. Its brightness is mostly due to its proximity to Earth. At a distance of 8.7 light years, it is the 5th nearest star system.
  • Procyon (+0.40) is another close neighbour with a distance of 11.4 light years.  It ranks as the sixth brightest star in our sky.
  • Pollux (+1.22) lies close to its slighter dimmer twin, Castor, in the constellation Gemini. Pollux is much more massive than the Sun and, despite being younger in age, it is in a more mature stage of its life cycle. Its nuclear furnace has already shifted from fusing hydrogen to helium into fusing helium into carbon and oxygen.  As the 12th brightest star in our sky, it falls just outside the top 10-list.

 

RASC Robotic Telescope

RASC’s national office is setting up a robotic telescope in California. The telescope will be used for a variety of observing activities that include education, outreach, astrophotography and science projects. RASC members can be part of one or several teams that match their interests and will share access to the image data collected by their teams.

Visit https://www.rasc.ca/telescope-news to keep up with the latest developments.

Image of NGC281
One of the first processed images from the RASC Robotic Telescope. NGC281 (total exposure 13.5 hours). Image credit: Francois Theriault from New Brunswick.

The telescope is located under very dark skies at the Sierra Remote Observatories in California. The main instrument is a 40 cm RCOS telescope on a Bisque Paramount-ME mount. The camera is a new large-chip SBIG STX-16803 CCD camera that provides a field of view of approximately 1/2°.  The telescope is equipped with a filter wheel and an adaptive optics unit. In addition, riding atop the telescope is a full-frame Canon 6D DSLR with a 200 mm f/2.8 lens for wider-field images.

The telescope is already taking test images and a astrophotography group will be set up first. After signing up, members will have access to raw data images from the telescope. To help those new to astrophotography, there will be training in how to process these images. There are also plans to provide access to the DSLR photos to all members.

Yukon Northern Lights Tour – Non-RASC Event

This is not a RASC event and there is a cost for the tour.

The Aurora | 360 tour is the ultimate way to experience the Northern Lights. On board a private charter jet, you’ll have the best access possible and with only 80 seats available, this exclusive opportunity comes with serious bragging rights!

Neil Zeller Photography: The Yukon
Neil Zeller Photography: The Yukon

The chartered jet will be available to hunt for the Auroral Oval above the clouds and it will be able to alter the flight path to maximize amazing Aurora viewing.  Scheduled to take-off from Whitehorse, Yukon,  between the 7th and the 11th of February 2019, the Aurora | 360 Experience offers 80 passengers an exclusive opportunity to witness the Aurora Borealis closer than ever before.

The tour offers a seat on the flight and a fully immersive weekend experience package with uniquely Yukon cuisine, Aurora based cultural and scientific presentations, tours, accommodations and guest speakers (Dr. Phil Plait, Dr. Christa Van Laerhoven, William Murtagh, Pierre Paquette)
To learn more, you can find information at aurora-360.ca and reserve spaces here Aurora | 360 – The Northern Lights like Never Before!

Pleiades, Pleiades, Pleiades, Pleiades

The Pleiades is a beautiful open star cluster in the constellation of Taurus. It is one of my favourite targets during star parties because it gives different views and perspectives at different magnifications from naked-eye views to spectacular telescopic images. Recently, at the Manning Park Dark Sky Weekend and a Starry Nights event, we had people progress from a naked-eye view to using 8x binoculars while they waited for their turn to look though the telescope.

Autumn in Manning Park
Autumn in Manning Park featuring the Pleiades star cluster. Image Credit: Rebecca Bollwitt

The cluster is also known as the Seven Sisters or Messier 45. It is obvious to the unaided eye: I see it as hazy bright patch from light-polluted city skies but individual stars can be resolved from a dark site; typically 5 to 6 member stars are visible to people with good eyesight. The cluster is located about 10° north-west of the bright orange star Aldebaran which can currently be found by looking due East around 08:30pm PST.

Pleides due East at 08:30pm on Nov 7th, 2018
The Pleiades can found by looking East from Vancouver at 08:30 pm on Nov 7th, 2018
The view of Pleiades through binoculars
Binocular View

The seven brightest stars are named for the Seven Sisters of Greek Mythology: Sterope, Merope, Electra, Maia, Taygeta, Celaeno, and Alcyone. These stars plus two more, named after their father Altas and mother Pleione are clearly visible in binoculars.

A telescope and eyepiece that gives a wide field of about 2.2° provides a glorious close up view of the main stars of the cluster plus additional dimmer stars. Galileo was the first person to view the Pleiades through a telescope and thereby discovered that the cluster contained stars not visible with the naked eye. I like to think that he said “Wow” like many our star party attendees.

Telescopic View
Wide Telescopic View: click for a larger view

Messier’s inclusion of the Pleiades as M45 in his catalog of comet-like objects is curious: it is much brighter than most of other objects in the catalog and cannot be easily mistaken for a comet.

The cluster’s core diameter is about 16 light years and it includes over 1,000 confirmed members excluding unresolved binary stars. Its light is dominated by young, hot blue stars. Swirls of nebulosity are noticeable around the brightest stars from dark skies when the moon is absent. The Pleiades’ nebulae are blue-coloured which indicates that they are reflection nebula – clouds of dust and gas that reflect the blue light of nearby stars.

Narrower Telescopic View
Narrower Telescopic View: click for a larger view.

This nebulosity can be glimpsed in higher-magnification telescopic views, though it often appears as faint bluish-gray patches through the eyepiece because our eyes are not sensitive to colour at low light levels. It was initially thought that the dust may have been left over from the formation of the stars in the cluster but later observations showed the cluster just happens to be moving through a dusty portion of our galaxy. How was this determined? The radial velocity of the stars was measured and found to be different from the velocity of the dust by about 11 km/sec.

The nebulosity becomes stunning in long exposure images like this one that took almost 12 hours.

Wide-field image
Long Exposure Image. Image Credit:: Marco Lorenzi (Glittering Lights) APOD 2015 June 17

I enjoy the views of this glorious cluster despite not knowing their proper pronunciation (PLAY-uh-deez, PLE-uh-deez, play-A-deez).

 

Outer Space Institute Conference at UBC

The Outer Space Institute is holding a conference at UBC on Nov 16th,  2018 to address two immediate near-term challenges in the sustainable development of space: space mining and orbital debris. The conference includes a free public half-day discussion and Q&A on the topics of asteroid mining, space debris, space colonization, and Canadian space policy.

RSVP here for the public event.

NASA: Artist's impression of the SLS Launch, bound for Mars (dhitt)
NASA: Artist’s impression of the SLS Launch, bound for Mars (dhitt)