Category: Astronomy

Iridium Flares and NOSS satellite pairs

With storm systems and cold fronts moving across the region last night the opportunity to do any sky watching seemed remote. And, yet, for a brief period, clear skies revealed the stars, moon, and satellites above northern Arizona.

First up was the X-37B at ~1805 MST. I watched — but did not photograph — this USAF spacecraft. I wish that I had because for a few seconds after it had passed maximum altitude it flared brightly – possibly rivalling Jupiter in brightness.

Iridium 98 satellite flaring along with the NOSS 2-2 (C) and NOSS 2-2 (D) satellite pair.
Iridium 98 satellite flaring along with the NOSS 2-2 (C) and NOSS 2-2 (D) satellite pair.

Next up was an Iridium 98 flare that was forecast to brighten to magnitude -6.5. This was easily captured by the camera but I was also able to capture two additional satellites travelling close together. A bit of investigation revealed that these were likely NOSS 2-2 (C) and NOSS 2-2 (D). NOSS is the Naval Ocean Surveillance System and these spacecraft travel in pairs and triplets.

I often use the information available at the Heavens-Above web site for satellite tracks and times. Below are the tracks for the Iridium98, NOSS 2-2(C), and NOSS 2-2(D) spacecraft.

Track of Iridium 98 for 12 November 2011.
Track of Iridium 98 for 12 November 2011.
Track of NOSS 2-2(C) for 12 November 2011.
Track of NOSS 2-2(C) for 12 November 2011.
Track of NOSS 2-2(D) for 12 November 2011.
Track of NOSS 2-2(D) for 12 November 2011.

There are hundreds of active satellites and thousands of objects (live satellites, dead satellites, and pieces of space debris) orbiting the earth. So it’s pretty easy to look up and see one of these moving across the sky. But it also makes it difficult to photograph the stars, planets, and other celestial bodies without getting a satellite track across the image.

Another Space Station in the Sky

We all know about the International Space Station (ISS). Many people have watched as it flies overhead as a brilliant point of light moving across the sky.

But now it is no longer the only space station in the sky. On 29 September 2011 China launched its own space station known as Tiangong (“Heavenly Palace”). It’s not as bright as the ISS and thus less noticeable to most observers.

Tiangong and Shenzou spacecraft moving across the pre-dawn sky.
Tiangong and Shenzou spacecraft moving across the pre-dawn sky.

Then, on 01 November 2011, China launched the Shenzhou-8, an unmanned spacecraft designed to dock with Tiangong. And early on the morning of 02 November 2011, both spacecraft passed overhead cutting through the constellation Orion. Just a few hours later, Shenzou-8 successfully docked with Tiangong.

The dual spacecraft flyby is reminiscent of the ISS-Shuttle flybys.

A bright flash in the sky

There are hundreds of operational satellites and thousands of unused satellites and satellite fragments orbiting the Earth. A few of these are quite bright and easy to see as they traverse the sky. Most are dim and generally not easily visible. And others are usually dim but briefly flare much brighter.

Satellite flare is caused by the reflective surfaces on satellites reflecting sunlight directly onto the Earth below and appearing as a brief, bright “flare.” The Iridium satellite series is especially conducive to reflecting light back to the earth and these flares can be exceptionally bright.

Satellite flare from Iridium 91 as it traverses the northern Arizona sky.
Satellite flare from Iridium 91 as it traverses the northern Arizona sky.

Here is an example of the Iridium 91 satellite as it traversed the northern Arizona sky and quickly brightened to a magnitude of -7.0 . Only the Moon (-13) and the Sun (-27) have brighter magnitudes.

Detail of a satellite flair from Iridium 91 as it traverses the northern Arizona sky.
Detail of a satellite flair from Iridium 91 as it traverses the northern Arizona sky.

Knowing when and where to look for Iridium flares is easy as there are many web sites that provide this information. My favorites are Heavens-Above.com and CalSky.com. Happy satellite viewing!

Biking the Rainbow Rim Trail along the edge of the Grand Canyon

In late June we packed our bikes and camping gear and headed to the Kaibab Plateau so we could mountain bike on the Rainbow Rim Trail. We’ve done this trail before but it’s such a great ride with amazing views that it’s always worth the long drive.

It takes about four hours to get to the trail head from Flagstaff. The last hour of driving is on Forest Service gravel roads through the aspen, pine, spruce, and fir forests of the high plateau of the Kaibab. We went to the south end of the trail at Timp Point and set up camp on the edge of the rim overlooking the Grand Canyon. After a quick lunch we were on the trail heading north.

The Rainbow Rim Trail (RRT) is about 18 miles from end to end with five points along the trail. From south to north they are Timp Point, North Timp Point, Locust Point, Fence Point, and Parissawampitts Point.

Riding along the edge of the Grand Canyon on the Rainbow Rim Trail.
Riding along the edge of the Grand Canyon on the Rainbow Rim Trail.

Each point delivers you a stunning view of the Grand Canyon. Between the points the trail heads in a generally eastward direction as it contours around side canyons. And it is these side canyons that are the most interesting. Because they are oriented east-west there is substantial shade in the canyons resulting in a cooler micro-climate. The south and shady sides of these canyons are filled with aspen groves as well as spruce and fir trees while the sunnier north sides have ponderosa pine and even juniper and pinyon trees. We even found some wild strawberry plants.

Lush forest found in the side canyons traversed by the Rainbow Rim Trail.
Lush forest found in the side canyons traversed by the Rainbow Rim Trail.

There are no large cities near the Kaibab Plateau hence there are no city lights. The nights are exceptionally dark and the stars are brilliant. Take some time to just lie back and stare up at the sky. It’s good for your soul.

The night sky as seen from the Kaibab Plateau.
The night sky as seen from the Kaibab Plateau.

The Arizona Trail (AZT) also traverses the Kaibab Plateau. Whereas the RRT is along the west edge of the Plateau the AZT is closer to the east edge but only overlooks the edge of the canyon in one location. In that regard, the RRT trumps the AZT.

The Jacob Lake District of the Kaibab National Forest has an informational page about this trail including access points, maps, and mileage.

The final flight of the Endeavour

As the Endeavour (STS-134) mission comes to an end NASA is one step closer to the final chapter of the Space Shuttle program. The Discovery has already flown its final mission. The upcoming flight of Atlantis will be the final and last shuttle mission.

ISS and STS-134 along with frozen cloud of ice particles from a vented tank over northern Arizona.
ISS and STS-134 along with frozen cloud of ice particles from a vented tank over northern Arizona.

Endeavour undocked from the International Space Station (ISS) at 8:55 pm MST 29 May 2011 (0355 UTC 30 May 2011) and began a slow separation from the ISS in preparation for its landing on Wednesday. The double flyby of the ISS and the STS-134 Endeavour over northern Arizona early this morning resulted in this spectacular image as the two spacecraft emerged from Earth’s shadow. In preparation for its return to Earth Endeavour had vented its tanks creating an ice cloud in space that was moving along with the two craft.

This is a composite of eight images of 15 seconds duration. There is a small gap between each image as the camera shutter briefly closed. Also visible in this image in the upper right is the faint track of another earth orbiting satellite — most likely COSMOS 2228 Nova 1.

Edit: Received information that the satellite is Nova1.