July 5, 1988

LEAD: THE Soviet Union, bidding for leadership in Mars exploration, plans to launch a pair of spacecraft this week and next on seven-month journeys to orbit the planet and dispatch landing vehicles to Phobos, a tiny gray moon believed to be an asteroid trapped by Martian gravity.

LEAD: An increase in production and new orders, fueled by a growth in exports, helped the economy expand in June at the largest rate since December, the National Association of Purchasing Management said in its monthly report scheduled for release today.

LEAD: A year-old program intended to speed experimental drugs to desperately ill patients has provoked a bitter debate over the right of the Federal Government to deny unproven therapies to dying patients.

LEAD: Amid a host of unanswered questions, the Pentagon today began a painstaking reconstruction of how an American warship mistakenly shot down an Iranian passenger jet over the Persian Gulf on Sunday.

LEAD: As the second half of the year begins, the prospects for lower interest rates over the next six months seem far brighter than most analysts said was possible even a month ago.