ASTRONOMY INTO THIN AIR
In June 2009, my climbing partner and I tackled the summit of Kilimanjaro in Tanzania. At 19,341 (5,895 meters), this dormant volcano is Africa’s highest peak and one of earth’s tallest freestanding mountains. The climb was a rare opportunity for me to combine my interests in astronomy, mountain climbing and geology into a single adventure. Kilimanjaro’s location in the dark skies of east Africa, and its high altitude, offered the potential for clear views of the southern skies and the chance to see new constellations not visible from my home in Florida.
In 1889 Dr. Hans Meyer, a German, became the first European to reach the summit of Kilimanjaro.
He commented on the beauty of the Kilimanjaro’s night skies in his 1891 book Across East African Glaciers:
“The higher we climbed the rarer grew the atmosphere and the more brilliant the light of the stars. Never in my life have I seen anything equal to the steady luster of the tropical starlight…”
Reaching Kilimanjaro’s summit presents several challenges. Although it’s not a technical climb involving ropes and pitons, it does require strength, endurance and the occasional scramble up rough volcanic terrain. There is always the possibility for rain, wind, extremely dusty conditions, and snowstorms. Furthermore, if you are unable to properly acclimatize to the thin mountain air, there is the risk for Acute Mountain Sickness (AMS) or the potentially fatal high-altitude pulmonary edema and high-altitude cerebral edema.
There are several routes to the summit, but based off the recommendation of our climbing company, Tusker Trail, so we chose the less traveled 10-day Lemosho- route, which allowed a full seven days for acclimatization prior to the summit attempt. This route also provided seven nights at camps above 11,000 feet, which is higher than the low cloud layers that typically surround the mountain.
One of my primary objectives was to photograph the southern skies with a DSLR on a tracking mount. My equipment included Canon 40D and Nikon D700 cameras, lenses with focal lengths from 14 to 200 mm, an AstroTrac TT320X tracking mount and Canon 10X42L image-stabilized binoculars. To protect the equipment from rain, dust, and a moderate amount of physical shock, I packed the gear in plastic cases and placed it in dry bags with clothing to provide additional protection.
Although Kilimanjaro is in the tropics, the high altitude causes the temperature to drop quickly as soon as the sun begins to set. By the end of astronomical twilight, temperatures were between 20° and 30° Fahrenheit (-7° and -1° C) and at the higher camps, the temperatures dropped into the lower teens by morning. This presented power challenges for the cameras and AstroTrac. After considering solar- powered chargers, I decided to get optional battery grips for both cameras and use Energizer Ultimate Lithium AA batteries. These non-rechargeable batteries can perform at temperatures as low as -40°F.
Another issue involved polar aligning the AstroTrac. Kilimanjaro is located only 3° south of the equator; thus, the south celestial pole is very near the horizon and, unlike the northern sky, there is no bright pole star to help with the alignment process. Prior to the climb, I used the planetarium program Starry Night Pro to gain familiarity of the stars near the south celestial pole and with the night skies of Kilimanjaro in general.
We began our climb on the western flank of Kilimanjaro near the Londrossi Gate at an altitude of 7,966 feet and spent about 3 hours hiking to our first camp at Mti Mkubwa (9,160 feet.) located within a forest zone. Along the way we saw Colobus monkeys and trees scraped by the elusive elephants that dwell in Kilimanjaro’s forests. By early evening, the Southern Cross was gleaming through a small break in the canopy of trees, and I took advantage of the imaging opportunity despite several bats flying very close to my head.
Our two Tanzanian climbing guides were very interested in my astronomy equipment. While the guides were familiar with high-end DSLRs, this was the first time a climber brought a tracking mount. With a green laser and the imaged-stabilized binoculars, I pointed out the stars and nebula in the region around the Southern Cross.
The next day we hiked beyond the montane forests of the lower slopes to moorland zone and our next camp on the Shira plateau at 11,381 feet. As the sun began to set, the mists and clouds descended well below our camp revealing a magnificently clear blue sky. I set up my astronomy gear eagerly awaiting the evening’s astronomical show to begin.
By 7:30 PM, I was witnessing the darkest skies and brightest stars of my life while standing in a giant amphitheater formed by Kibo to the southeast and the rim of the Shira’s caldera to the south. The Milky Way galaxy was rising over Kibo, and Eta Carina shined brilliantly over Shira’s caldera rim.
The day before our summit attempt, we climbed to the high-desert regions where it is ‘”summer every day and winter every night”. Conditions became increasingly barren and extreme and we noted only a few lichens clinging to rocks worn smooth by glaciation. We set up camp at Barafu (15,157 feet) where a couple of other climbing teams were preparing for their midnight ascent to Kilimanjaro’s summit. By 4:30 AM, we could see their headlamps as they made their way up Kibo’s steep slopes in the moonless, starlit night.
Reaching the Top
Our own summit attempt began prior to sunrise. The guides woke us at 5:00 AM and performed one final medical check. After seven days acclimatizing, it was finally time to climb to Africa’s highest point. The trail was steep and we were quickly over 16,000 feet looking down on Barufu Camp. For the next five hours we hiked Pol’e Pol’e (Swahili for “slowly, slowly”) to carefully avoid over exerting ourselves and increasing the risk of acute mountain sickness.
The sunrise at this high altitude was stunning, and soon we were climbing under crystal-clear cobalt-blue skies. About four hours into the climb, we obtained our first close up views of a one of Kilimajaro’s glaciers. It was a bit surreal knowing we were near the equator while standing next to the towering 60-foot layers of blue-white ice making up the Rebmann Glacier.
We reached Stella Point (18,471 feet) in about five hours feeling surprisingly well as we stood on the rim of Kilimanjaro’s caldera. After lunch, we resumed the climb up the southwest rim of the caldera. We reached Kilimanjaro’s summit (19,340 feet) a little after 1:00 PM – the culmination of nine months of preparations and eight continuous days of climbing. The views from the summit were fantastic.
After about an hour, we descended 800 feet into the caldera down a very steep “trail” composed mostly of volcanic scree. Our camp was established about 1,000 feet from Furtwangler Glacier. After resting for a couple of hours, we set out slowly across the caldera floor and I was amazed at how similar the terrain was to images of the Martian surface transmitted by NASA’s venerable robotic explorers Spirit and Opportunity.
Volcanic rocks of various sizes were distributed randomly across the dusty, wind-blown floor of the caldera. The dust kicked up by each footstep was very fine and seemed like a dull brown talcum powder. The smell of sulfur permeated the air, and occasionally we could feel warmth we thought may be from the fumaroles located within the pit. We did not stay long; we were feeling the effects of the high altitude and it was time to return to camp.
As the sun was setting, the wind picked up significantly. Although the astronomy gear was ready to be deployed, the wind would not allow the stability required for long exposures – there would be no imaging from Crater Camp. As the evening progressed, the temperature dropped precipitously – down to about 13°F. During the night, I did poke my head out of the tent more than once to see the stars and the Milky Way stretched from one side of the caldera to the other side shining brilliantly over Kilimanjaro’s glaciers. Just before sunrise, we were greeted with a beautiful grouping of Venus, Mars and the thin crescent Moon.
After the long, cold night, we packed up and prepared for our two-day descent from Crater Camp. Our water bottles were almost completely frozen and I could now clearly feel the effects of remaining so long at this high altitude. We descended the mountain very quickly, dropping over 8,534 feet in a single day. The next morning, we hiked through the rain forest to the Mweka Gate (5,384 feet) and departed Kilimanjaro National Park.
Seeing the night skies of Kilimanjaro was a delightful experience. The image-stabilized binoculars provided exceptional wide-field views of constellations and other astronomical targets. Nevertheless, the amount of time spent observing and imaging after a long day of climbing had to be balanced with the need carefully attend to our physical condition. I found myself trading a good polar alignment and time spent shooting photos with needed sleep for the next day’s climb.
In the past I had traveled to some very interesting and remote locations often lamenting not being able to capture the brilliance of a superbly dark sky. But the portability provided by the AstroTrac and the capabilities of today’s DSLRs coupled with the performance of lithium batteries, gave me the opportunity to image the skies while climbing Kilimanjaro. The 10 days we spent in the East African wilderness were a magnificent experience. The location is truly one of the unique environments on the planet. And it can only be reached with a good pair of hiking boots, a backpack, and in my case, portable astro-imaging equipment!