NEW YORK - There are just 3,000 Jews living in Alaska's 570,374 square miles, but Yossi and Esty Greenberg are there to serve them - leading services, throwing Hanukkah parties, flying deep into the bush to train a young man for his bar mitzvah.
It's not easy. The food stocked by the local store is not kosher enough for the Greenbergs; the family's meat, bread and dairy products must be flown in from the lower 48. When their eldest son turned 9, he had to be sent to Chicago for his education. And every month Esty had to fly to Seattle for her ritual bath until a mikvah was built in Anchorage.
And yet, the Greenbergs aren't complaining.
"We feel like we are the only people on Earth walking around with a sense of purpose," Yossi says. "We feel we know who we are and where we are going."
The Greenbergs did not grow up in Alaska - they were sent there, emissaries of the Lubavitcher Hasidic movement. They are one of more than 3,800 husband-and-wife teams that have been sent to 45 states and 61 countries on a mission to encourage Jews to become more observant.
The Greenbergs merit a chapter ("The Frozen Chosen") in writer Sue Fishkoff's new book, "The Rebbe's Army: Inside the World of Chabad-Lubavitch," published by Schocken Books. They are atypical in their frigid posting, but typical in their energy and zeal.
Fishkoff came to rely on her subjects' inexhaustible stamina. "After a while, I expected them to go all day and then sit down at midnight for an interview," she says.
Like others among the ultra-Orthodox, the Lubavitchers are strictly observant - bearded men in black hats, bewigged women in modest garb. But unlike Hasidic sects which separate themselves from the modern world, the Lubavitchers are outward looking.
In Los Angeles, Chabad (the Lubavitcher movement's name - an acronym of the Hebrew words for wisdom, comprehension and knowledge) holds a yearly telethon to raise millions for drug treatment. Appearances by celebrities like actor Jon Voight are interspersed with rousing folk dances.
Chabad deploys teenagers to work the streets of cities around the country, seeking out Jews and asking them to perform rituals like lighting sabbath candles or putting on phylacteries, leather boxes containing passages from Scripture. It erects large menorahs in public places each Hanukkah. It has built a worldwide network of Chabad houses to serve campuses and communities.
Other books have examined the lives of Lubavitcher Hasidim - most notably "Holy Days" by Lis Harris, published in 1985. But Fishkoff's focus is the shlichim, the emissaries who are dispatched to build Chabad houses with nothing but a year's seed money and a blessing.
Their passion was ignited by the charismatic Lubavitcher rebbe, Menachem Mendel Schneerson, who took a small group of Holocaust refugees and transformed it into an international phenomenon. His picture graces every Chabad house; his writings and speeches are collected and studied. The tales of his wisdom are told and retold.
But the Lubavitcher rebbe died in 1994. He left no successor, only a nasty dispute within the movement over whether Schneerson was the messiah he had trumpeted for so many years.
Still, Chabad survived - and grew.
"It's amazing to think that there are less than 200,000 Lubavitcher Hasidim in the world, and yet every Jewish person seems to have had some contact with them," Fishkoff says.
She attributes the movement's success to "an internal fire," and to "a desire of the general public ... to turn back to religion."
Again and again in the course of her book, she shows how Reform and Conservative Jews give money to Chabad, though they do not agree with many of its tenets, such as the requirement that men and women be separated during services. If Chabad embraces all Jews, it is clear that a lot of Jews are happy to be embraced.
Fishkoff believes that Chabad eventually will be transformed from a Hasidic sect into a fourth major branch, along with Reform, Conservative and Orthodox Judaism.
Fishkoff, herself, remains a "card-carrying Conservative Jew." But she acknowledges that she has been changed by her interactions with the Lubavitchers.
"My comfort level in any religious setting had increased," she says. "I'm more aware of my responsibilities as a Jew."
The lesson of Chabad, she says, is that "You can actualize the Jewish values that we learn about in Hebrew school and you can do it every day. Visiting the sick, paying condolence calls, being careful not to embarrass people - these are the kinds of things the shlichim do all the time, and these are the kinds of things we all can do."